^^«ftli*'aUt«*l!Wit«tli£Ac*v«* CORNELL UNIVERSITY LIBRARY The original of tiiis bool< is in tine Cornell University Library. There are no known copyright restrictions in the United States on the use of the text. http://www.archive.org/details/cu31924012393157 The D. Van Nostrand Company intend tbis book to be sold to the Public at the advertised price, and supply it to the Trade on terms which will not allow of discount. PLATTNER'S MANUAL OF QUALITATIVE AND QUANTITATIVE Analysis with the Blowpipe TRANSLATED BY HENRY B. CORNWALL, E.M., Ph.D. Professor of Applied Chemistry and Mineralogy in Princeton University ASSISTED BY JOHN H. CASWELL, A.M. EIGHTH EDITION, REVISED AFTER THE SIXTH GERMAN EDITION BY Professor FRIEDRICH KOLBECK Of the Mining Academy at Freiberg, Saxony WITH EIGHTY-SEVEN WOODCUTS NEW YORK D. VAN NOSTRAND COMPANY 23 Murray Street and 27 Warren Street 1902 tf'kWi (I. II : i> A t' V 6U) 'pni (1Q2 Copyright, 1902, BY D. VAN NOSTEAND COMPANT. FEOM THE TEANSLATOE'S PEEFACB, PIEST EDITION. The growing interest in blowpipe analysis which is evident in this country has induced the translator to present to our scientific students the following translation of Plattnee's unequalled manual, and it is further hoped that this book may be the means of bringing into more prominent notice a branch of blowpipe analysis which has been too long neglected, viz.: quantitative assaying. The present work is a translation of Plattnee's book, in which nothing of the slightest importance has been omitted, while its size has been reduced as much as possible by avoiding unneces- sary repetitions and by using concise language. If any apology is necessary for the size of Plattnee's work it is to be found in the character of the author, who investigated in the most thorough manner every subject upon which he entered. 'Not is there any reason why the beginner should not take up the study of blowpipe analysis with this thorough manual in his hand to explain to him the difficulties which will meet him almost at the outset. It is only necessary that he should have some advice regarding the way in which the book is to be used, and this the translator has endeavored to give in a short introduction. My sincere thanks are due to Professor Eiohtee for the very kind response which he has made to various inquiries, and for a valuable list of alterations which he has furnished as necessary to the completeness of the book; to Professor Bgleston, of the School of Mines, Columbia College, New York, for many valuable suggestions during the preparation of this translation; and to Mr. Caswell for able assistance in accomplishing the task. H. B. Coenwall. New Yokk, July 1st, 1871. PEEFACE TO THE EIGHTH AMEEICAN EDITION, All students of blowpipe analysis know how to value the classical work of Plattwee and of his successor, Eichteb; and to them the present edition will be welcome, because it has been thoroughly revised, after the latest German edition, which brings the book well up to date. Besides the addition of many new minerals, and of the latest approved tests, the work has been im- proved by adopting modern chemical notation, by omission of superfluous or antiquated tests, as well as some less important quantitative determinations, e.g., iron and chromium. Also by omission of spectroscopic methods, which do not properly belong to blowpipe analysis, and by correction of a few typographical errors. H. B. COENWALL. Peinceton, N. J., January 1st, 1902. [iv FROM THE PEEFACE TO THE SIXTH GEEMAIST EDITION. At the desire of the editor of the fourth and fifth editions of C. P. Plattnek's Blowpipe Analysis, Professor Theodoee EiCHTEK, Ph.D., Geheim-Bergrath, the publisher of this book has entrusted to me the revision of the sixth edition. I learned to know and value the excellence of Plattnee's work while for many years assistant to Dr. Eichtek, an unsurpassed master of blowpipe analysis, to whom it has been a labor of love to preserve and extend what he has attained through forty years in this domain. There has been no occasion for essential changes, since experi- ence has taught that, with the aid of the methods given by Platt- nek and Eichtbe, results are quickly and surely attained by those having sufBeient practice in the use of the blowpipe, which can be best obtained by thorough instruction. Among the additions is the blowpipe behavior of several minerals which have been discovered since the fifth edition was published. The size of the book has been notably diminished by abbrevia- tions and more concise descriptions, and by omission of less im- portant passages, whose selection has been approved by Dr. Eichtee. Fbiedeich Kolbeck. Feeiberg, Saxony, July, 1897. CONTENTS. PA.SE Translator's Prefaces iii Preface to German Edition v Introduction xiii FIEST SECTION. APPARATUS AND BBAGEKTS. I. The blowpipe 3 II. The fuel, blowpipe lamp, gas lamp, gas blowpipe, spirit lamp 8 III. The blast and flames 10 1. The oxidizing flame la 3. The reducing flame 14 IV. The support 15 a. The direct support (coals, platinum wire, etc., glass tubes, clay crucibles, bone-ash) 15 b. The indirect support (soda paper, charcoal and fire-clay) .... 25 V. Instruments, small vessels, and other apparatus 26 VI. Blowpipe reagents 45 A. Reagents for analyses which are conducted by the dry method alone 45 a. General reagents > 45 J. Special reagents, only used in certain tests 50 B. Reagents used in analyses conducted with the aid of the wet method 53 a. General reagents 53 -6. Reagents of limited use 54 SECOND SECTION. QUALITATIVE BLOWPIPE ANALYSES. I. General rules 59 A. General rules, according to which the behavior of minerals and other substances before the blowpipe can be determined, and a considerable proportion of their constituents dis- covered 59 vil Till CONTENTS. PAQE a. Testing without reagents 60 1. Examination in the matrass, or the closed tube 60 3. Examination in the open tube 63 3. Examination on charcoal 65 4. Examination for fusibility and coloration of the flame 70 b. Testing with reagents 77 1. Examination with borax 79 2. Examination with salt of phosphorus 84 3. Examination with soda 88 4. Examination with cobalt solution 91 B. General rules for qualitative blowpipe examinations, by which the separate constituents of compound substances can be detected, with the partial aid of the wet process 93 Solution of substances in water or hydrochloric acid 93 Decomposition of substances by fusion with soda and borax, and treatment of the fused mass with hydrochloric acid 94 Fusion of substances with nitre or bisulphate of potassa 97 II. Qualitative examination of minerals, ores, and metallurgical products before the blowpipe for metallic and non-metallic bodies 100 Numbers indicating the fusibility of the silicates and their be- havior with hydrochloric acid 100 A. Examinations for alkalies and earths. ; 101 Potassa 101 Soda lOo Lithia 109 Ammonia 112 Baryta 112 Strontia 116 Lime 117 Magnesia 130 Alumina 138 Glucina 146 Tttria and Erbia 149 Zirconia 159 Thoria 163 B. Examinations for metals or their oxides 165 Cerium, Lanthanum, and Didymium 165 Manganese 171 Iron 178 Cobalt 197 Nickel 202 Zinc 209 Cadmium 216 Lead 317 Tin 233 Bismuth 236 Uranium 342 CONTENTS. IX PAOB Copper 246 Mercury 360 Silver 264 Platinum, Palladium, Ilhodium, Iridium, Ruthenium, and Osmium . 372 Gold 275 Titanium 379 Tantalum and Niobium (columbium) 283 Antimony 284 Tungsten 390 Molybdenum 293 Vanadium 295 Chromium 297 Arsenic SCO Tellurium 307 C. Examinations for non-metallic bodies and acids 309 Water 309 Nitric Acid 810 Carbon and Carbonic Acid 311 Boron and Boracic Acid 315 Silicium and Silicic Acid 317 Sulphur and Sulphuric Acid 319 Selenium 323 Phosphorus and Phosphoric Acid 324 Chlorine 326 Bromine 337 Iodine 338 Fluorine 329 Cyanogen 330 III. Examples showing the method of detecting the constituents of vari- ous compounds with the help of the blowpipe 832 A. Oxysalts, Chlorides and Fluorides 332 B. Silicates and Aluminates 337 C. Combinations of Metallic Oxides 840 D. Sulphides, Selenides, and Arsenides 340 E. Combinations of metals containing no arsenic or sulphur, or but very little of either 843 THIRD SECTION. QUANTITATIVE BLOWPIPE ASSAYS. I. Preparation of the substances 849 II. Detailed description of the quantitative assays 350 1. The Silver Assay 350 A. Assay of ores, minerals, etc., in which the silver is especially combined with non-metallic bodies. a. Substances which contain volatile constituents, viz.: sul- CONTENTS. PAOB phur and arsenic, as well as chlorine, bromine, and iodine, in greater or less proportion, or are entirely free from them, and can be reduced by fusion on coal with borax and test lead 351 Table showing the cupellation loss 364 6. Minerals containing compounds which cannot be decom- posed by fusion with borax and test lead alone 366 c. Metallurgical products consisting of metallic oxides that are readily reduced on coal 367 B. Assay of metallic compounds (alloys), a. In which silver is a chief constituent 368 6. In which copper or nickel forms the prevailing constituent, and silver only a minor one 369 e. In which lead or bismuth is the chief constituent 370 d. In which tellurium, antimony, or zinc is the chief constitu- ent 371 e. In which tin is the chief or only an accessory constituent... 372 /. In which mercury is the prevailing constituent 373 g. In which iron or steel is the chief constituent 373 2. The Gold Assay 374 A. Assay of gold ores, auriferous silver ores, and argentiferous and auriferous metallurgical products 375 B. Assay of metallic compounds, a. Consisting only of gold and silver 878 b. Containing, besides gold and silver, other metals, viz.: Copper, platinum, iridium, palladium, and rhodium 381 •c. Consisting of gold and mercury 384 3. The Copper Assay 385 A. Ores, minerals, and metallurgical products, a. Containing volatile constituents : sulphur, arsenic, and selenium 385 b. Containing copper in an oxidized state, free from, or com- bined with, acids and water ; or slagged with earthy matters, or combined in any other way 891 B. Alloys, a. Of copper and lead 393 b. Of copper with iron, nickel, cobalt, zinc, and bismuth ; either singly, or with several at the same time, while lead, antimony, and arsenic are frequently present 395 c. Copper and antimony 397 d. Copper and tin 397 4 The Lead Assay 399 A. Ores, etc., containing the lead as sulphide 399 First method 399 Second method 403 B. Ores, etc., containing the lead as chloride or oxide, free, or in the form of slag, or combined with acids 406 CONTENTS. II PiGK C. Minerals containing lead in the metallic state combined either with selenium or with other metals 407 6. The Bismuth Assay 407 A. Minerals, etc., containing bismuth in the metallic state ; either mixed only with earthy substances, or arsenides of cobalt, nickel, and iron ; or else chemically combined with tellurium or selenium 408 B. Minerals containing bismuth as sulphide ; either alone or chemically combined with other metallic sulphides or arsen- ides 411 C. Metals, etc., containing bismuth as oxide ; free, or combined with carbonic, phosphoric, or silicic acids, etc., and possi- bly mingled with oxides of copper, nickel, and cobalt, or their salts ; or else containing the bismuth combined with chlorine •. 413 6. TheTinAssay 414 A. Minerals, etc., containing tin as sulphide, or as oxide mixed with sulphides and arsenides 415 B. Minerals and products containing tin as oxide 420 C. Alloys 423 7. The Cobalt and Nickel Assay 434 A. Assay for cobalt and nickel, and bismuth if necessary, in min- erals, etc., which contain the cobalt and nickel combined with arsenic, and sometimes with a little sulphur, but are free from copper 438 B. Assay for cobalt and nickel, and, if required, for lead, bis- muth or copper, in minerals, etc., containing cobalt and nickel, with perhaps other metals, combined partly with arsenic and partly with sulphur 431 C. Assay for cobalt and nickel in minerals, etc., containing nickel and cobalt as oxides, combined with arsenic or arsenous acids, or other metallic oxides, and sometimes with water. . 487 D. Mixtures of metallic oxides consisting especially of oxides of cobalt or nickel 438 E. Minerals and products consisting of alloys, or of arsenides and sulphides, in which there is more copper than nickel 441 8. The Mercury Assay 443 APPENDIX. The employment of quantitative assays with the blowpipe for the de- termination of various substances in quantitative chemical analysis . . . 443 Index to minerals mentioned in Section II 445 Index to metallurgical products mentioned in Section II 455 General Index 457 Atomic Weights of the Elements 463 mTEODUOTIOK Pbobablt no better course of instruction in blowpipe analysis can be suggested than that pursued by Prof. Richter, for the instruc- tion of his classes at Freiberg, and that will therefore be briefly given here, after a few introductory remarks, designed to aid the student in the use of this book. The student should first learn to produce the oxidizing and reduc- ing flames at pleasure, testing them according to the directions given on p. 13, et seq. Whenever after this he employs either fl ime he must consider carefully what will be the result ; whether the substances he treats will be reduced to metal, or only to a lower state of oxidization; whether they will volatilize and form a coat, or whether they are fixed ; whether they yield difierent colors with the fluxes, in the different flames (as is usually the case), etc., etc. To learn this he must prepare himself by studying thoroughly and performing faithfully the tests of the more common simple sub- stances as given in the tables, p. 82, et seq., and by a careful study of the facts stated under the general examinations for the bases and acids, beginning with p. 100. When thoroughly familiar with the behavior of the simple sub- stances, he should proceed to the analysis of mixtures, which may be finally made very complicated. By intelligently studying the prop- erties of the simple substances as given in the tables and under the general remarks, before referred to, and by following the general rules for qualitative analysis, p. 59, et seq., the student can deduce a sys- tem of examination for himself, which he can vary to suit difier- ent circumstances. Sometimes special tests are to be made, since thus certain substances, as mercury, manganese, sulphur, etc., can be most readily detected ; for some substances special tests are necessary, while others can be found in the regular course of analysis. All phenomena must be carefully noted, and the effect of each operation considered. If a coat is formed on coal, the student should remember what substances could yield such a coat, and how they xiii XIV _ nfTEODUCTIOir. may be separated from one another. If a powder lias been dissolved in borax and is then to be reduced, he should consider what sub- stances wUl be reduced from it, and in what condition those which remain dissolved will be found. As regards the reduced substances he should consider whether they will be volatile or fixed ; and if fixed, how they may be separated from one another. In learning to do this the examples given for practice, p. 332, et seq., will be found of very great service, as they exemplify the course which is to be followed in similar cases. The following substances were given by Prof. Eichter to the stu- dents under his instruction, to illustrate, in order, the different testa. 1. Testing on charcoal, to observe the coats, flames, etc. Selenium, arsenic, antimony, thallium, lead, bismuth, cadmium, zinc, tin, molybdic acid, silver, silver and lead, potassium sulphate, lead chloride. (Also a bismuth test with potassium iodide and sulphur.) 3. Testing in the matrass, to observe phosphorescence, decrepitation, change of color, evolution of gases, etc. Fluorite, apatite, siderite, cerussite, pyrolusite, potassium chlo- rate, natrolite, alum, calomel, ammonium nitrate, retinite. 3. Testing in the closed tube, to observe tohether there is any subli- mate formed. Zinc blende, pyrite, copper nickel, chloanthite, orpiment or realgar, antimony trisulphide, cinnabar, copper amalgam. 4. Testing in the open tube, to observe the formation of sublimates, sulphurous acid, or other gases. Pyrrhotite, copper nickel, stibnite, cinnabar. 5. Testing in the platinum forceps, as to fusibility, color of the^ flame, etc. Hematite (infusible in 0. F., fusible in K. F.), pyrophyllite, sodium carbonate,* natrolite, potassium carbonate,* aluminite, lepidolite, spodumene, petalite, strontianite, fluorite, calcite, chry- socolla, ammonium borate, boracite, datolite, borax* (with sul- phuric acid), tourmaline, barite, witherite, barytocalcite, molyb- denite, diadochite, apatite * (with sulphuric acid), atacamite, cupric oxide (in S. Ph. bead, and with addition of salt), cerussite, pyromorphite, scorodite. 6. For practice iti roasting. Copper pyrites. 7. Examination with borax bead. Sesquioxide of iron, vanadic acid, sesquioxide of chromium, cupric oxide, oxide of cobalt, oxide of nickel. 8. Examination with salt of phosphorus bead. * On platinum wire. INTEODUCTIOlir. XV Bismuth trioxide (with tin on coal), sesquioxide of iron, vanadic acid, uranio oxide, molybdio acid, cuprio oxide (with tin on coal), tungstic oxide, titanic oxide (the last two being also tested in E. F. with addition of sesquioxide of iron), peroxide of manganese (with addition of nitre to the hot bead). 9. Test for sulphur. With soda and silica on coal in E. F.; also with soda in E. F., and then with bright silver foil. 10. Test for manganese. With soda and nitre on platinum foil. 11. Tests with cobalt solution. Potash alum, magnesium sulphate, magnesium borate or phos- phate, zinc oxide, binoxide of tin. 12. Substances to illustrate the regular course of examination. Potassium chloride, potassium bromide, barytocalcite, boracite, fluorite, borax, alunite, wolframite, titanic iron, smithsonite (cad- miferous), annabergite, cerussite, wulfenite, pyromorphite, crocoite, libethenite, pitchblende (uraninite), earthy cobalt, cassiterite, cobaltite, berthierite, alabandite, stannite, tetrahedrite (mercurial). Prof. Bgleston arranged and published in the American Chemist, April, 1873, an excellent scheme of examination for the metallic oxides, used with marked success in the School of Mines of Colum- bia University, and given, almost as published, on the next page. In using the scheme, attention should be paid to the following note: Note.— The scheme is to be varied slightly according to circnmstancea. If sulphides, ■rsenides, etc., are under treatment, the sabstances mast be carefally roasted ; but if test 1 fails to show S, As, Sb, or Se, as sulphides, arsenides, etc., the substance is either an oxide or an alloy. If an oxide, the roasting, S, is omitted. If an alloy, it is snbjected to the test 1, a, foi Pb, etc., and then the test 2, A is performed by fusing the alloy on coal with borax in the R. F., thas combining 2, A, and 3, A, a, in one operation. Some sulphides during the roasting, 2, A, vill reduce to metal, and then after thorough roasting are to be treated like alloys. A metal oi raw sulphide, etc., must never be treated on platinum wire, but the metal is fused on cool with the flux ; in B. F., if it is desired to get only non-reducible metals, as Fe, Co, etc., in the flux; in O. F., if Cu, M, and other reducible metals are to be fluxed. The flnx is then transferred to the wire. Sulphides, etc., must always be roasted before testing with borax and S. Ph. The word bead always refers to the flnx, and bntton to the metal. In regard to 2, B, Sn can always be found in presence of Zn by reducing the oxides with soda and a little borax, and tri turating the mass with water, p. 90. In certain alloys, <. g. bronzes, containing both Sn and Zn, the Zn can be detected by treating a short time in R. F. and testing the coat formed wifb n)l)alt solution, as the Zn is more volatile and comes off first. SCHEME OP BLOWPIPE ANALYSIS. BT PROF. T. EGLESTON. The substance may contain As— Sb— S— Se— Te— Fe— Mn— Cu— Co— Ni-Pb— Bi— Ag— Au— Hg-Zn— Cd-Sn— CI— Br-I— CO'— SiO» — N^O'- H'O. 1. Treat on Ch. in the O. F. to find volatile substances such as As — Sb — S— Se— Pb— Bl— Cd, etc., p. 65 et seq. ; and also test in the open tube to find whether As, Sb, S are present as arsenides, etc., or in the oxidized gtate, p. 03 ttiieg. a. If there are volatile substances b. If there are no volatile sub- present, form a coating and test it tances present, divide a part of the withS. Ph. andtinonCh. forSb*p.885, substance into three portions and pro- or to distinguish between Pb and ceed as in A, Bl, p. 388. a Tellow coat, jieldiog with S. Fh. a black bead ; diBappearing with bine flame, no part of It yIeldVng greenish Sb flame; Pb and Bl« 13 Yellow coat, generally with white border, yielding black or gray bead with 3. Ph., disappear ing with bine flame ; also the border disappearing with greenish flame ; Pb and Sb. y Yellow coat, very similar to b, hut yielding no blue flame ; Bi and Sb. Make a special test for Bl, p. 239. Pb in presence of Bl, if not in too small quantity, is to be detected by the blue flame yielded by the coat or by the reduced metal itself. See also p. 339. 3. If As — Sb — S — Se are present, roast a large quantity thoroughly on Ch., p. 78. Divide the substance into three portions, and proceed as in A. (See note on p. xv.) A. Treatment op the Fibst Portion. — ^Dissolve a veiy small quantity in borax on platinum wire in the O. P. and observe the color produced. Yarioua colors will be formed by the combination of the oxides. Saturate the bead and shake it off into the porcelain dish ; repeat this once or twice, p. 79. a. Treat these beads on Ch. with a small piece of lead, silver, or gold, in a strong R. F., p. 94. b. Fe — Mn — Co, etc., remain in the bead, p. 96. If the bead spreads ont on the Ch., It mnet b* collected to a globule by continned blow- ing. Make a borax bead on platlimm ?rlre and dls- •olve in it earm of the fragments of the bead, reserring the rest for accidents. c. Ni— Cn— Ag— An— Sn— Pb— Bi are reduced and collected by the lead button, p. 96. (Sn, Pb, and Bi, if present, will partly volatilize.) Remove the lead button from the bead while hot, or by breaking the latter, when cold, on the anvil between paper, carefully preserving all the fragments. d. If Co is present, the bead will be blue. If a large amonnt of Fe Is present, add a tittle borax to prove the presence or absence of Co, p. 183. If Win Is present, the bead when treated on platinum wire In the O. F. will becomci dark violet or black. e. If only Fe and Mn with no Co are present, the bead will be almost colorless Look here for Cr, Tl, Mo, V, IT, T, Ta by the wet way. (A notable amonnt of Ti may be detected with S. Fh. and tin in the ori- ginal oxides, In absence of other coloring non- reducible oxides, p. 380. ITIo will be shown by the cloudy brown, or black appearance of the bo- rax bead in R. P. on platinum wire, p. 83.) • The flame test, p. 67, will often serve to detect Sb. xvi SCHEME OF BLOWPIPE AN^ALYSIS. XVU /. Treat the button c on Ch. in the O. P. until all the lead, etc., is driven ofiE ; Ni, Cu, Ag, Au remaining behind ; or separate the lead with boracic acid, p. 393. g. Treat the residue g on Ch. in 0. F. with S. Ph. bead, removing the button while the bead is hot. ft. If Ni and Cu are present, the bead will be green when cold, p. 250. If Ni only — yellow. If Cu only— blue. Prove Cu by treating the S. Ph. bead with tin on Ch. in the R. F., p. 251. i. For Ag and Au nnake the special test No. 8. B. Treatment op the Second Pobtion. — Drive oflE the volatile substances in the O. F. ou Ch. Treat with the R. P. , or mix with soda, and then treat with the R. P., for Zn, Cd, Sii. If a white coating is formed, test with cobalt solution, pp. 211, 216, 233, 92. It Zn is found, it is not generally necessary to look tor Sn, and vice versa, as they very rarely occur together. (See note, p. xv.) C. Treatment of the Third Pobtion. — Dissolve some of the substance in: 5. Ph. on platinum wire in O. P., observing whether SiO' is present or not, and test for Mn with potassium nitrate or soda, p. 173. 3. Test for As with soda on Ch. in the R. P., or with dry soda in a closed tube, p. 301 et seq. 4. Dissolve in S. Ph. ou platinum wire in the O. F. (if the substance is not metallic and does not contain any S), and test for Sb on Ch. with tin in the R. P., p. 285. (To detect a little Sb with Cu or Su, see p. 288.) 6. Test for Se on Ch., p. 323. 6. In absence of Se fuse with soda in the R. P. an J 1 1 1 Fiir. 2. i « PLATTKER'S blowpipe AKALYSI3. scarcely be held with the naked fingers, and blowpipes are generally made of brass or German silver. Mitscherlich has proposed a very convenient blowpipe, of some- what different construction, for travelling, which is shown in Fig. 3. The cylindrical part, A, serving to retain the moisture, is attached to the long tube, which unscrews in the middle at B, while the smaller tube, a i, can be slipped into the half that is fastened to the moisture reservoir, and the other half, C, the mouth-piece of which, D, should be covered with silver when the whole is of brass or German silver, can be put over this like a case. The cylinder thus formed can be conveniently carried in the pocket. If the blowpipe is to be used for glass blowing, the tube. Fig. 3, bent at a right angle, can be employed, as Berzelius has described. This is fixed in the opening, a, J Fig. 1, and can be inclined at any required angle with the long tube. The blowpipe can in this case be held fast in the month, either without a mouth- piece, or with a broad bone mouth-piece. Fig. 4, so that both hands are free. A still better arrangement for this purpose is shown in Fig. 5. Upon the board, b, is fixed a metal plate with a vertical slit in which the brass piece, k, taking the place of the moisture reservoir, A, Fig. 1, of the ordinary blow- pipe, fan be moved up and down and turned at pleasure, being held fast in the required position by a nut, not seen in the drawing. The female screw, !, on the other side, serves a like purpose for the short knee, m, in which the blowpipe tube, /■, is placed. In the brass piece, k, there is likewise an open- ing for the exit tube, o, to which any desired inclination can be given by by turning k. The parts of an ordinary blowpipe can be used for o and r. The lamp, /, is likewise set directly upon 4. t^^^^^^^^^^^^^^^ ^ Much trouble has ^^^^^^^^^^^^^^^ ^^^ been expended in jS^^^^^ ^^r constructing con tri- ll .^^ vances by which a MH ^^^ blowpipe flame can ^/^^!^f^^ be produced without ^^^ ^^ human lungs. With- E^^M ?:B rj^^ La^^ out entering into a ^ ' discussion of all the pieces of apparatus, the oldest of which are mentioned in Berzelius's work above cited, one alone will be more nearly considered here, which satisfies all the requirements that can be expected from such an arrangement ; it is the caoutchouc bellows. On a small board, I, a, metal rod, s. Fig. 6, is fixed by means of a joint, so that it can be THE BLOWPIPE AND ITS USE IN CHEMISTRY, ETC. 7 moved toward one side, and on this, the metal piece, c, which can be secured at pleasure by the screw, g, moves up and down. The exit tube, i, can thus receive any inclination and position with regard to i;he blowpipe lamp, a. Thebellows,5,thotube,/fc,aiidthe reservoir,/?, :are for the most part constructed of vulcanized rubber; v and v' are valves. By compressing B with the hand, or upon the floor with the foot, and letting it expand again, the air enters at v and is expelled through v' and the tube k into the reservoir R and the tube i. After a few experiments with the position of the tube i, and a stronger or -weaker pressure of the bellows, facility in constantly maintdaing ihe different flames is acquired. Some changes in this apparatus have been proposed by Jung^i and Mitzopulos {Berg- u. Huttenm. Zeit.. 1872, No. 2,) and Osius and Osterland {Berg- n. Hiittenm. Zcit., 1862, No. 13). Other ways of arranging the blowpipe are given by Moses {Berg- 11. Huttenm. Zeit., 1865, No. 41,) Landauer {Lothrohranalyse,) Kaps {DingJer's polyt. Jour., vol. 313, p. 203,) Eiiger {Berg- u. Hiit- tenni. Zeit., 1869, No. 17, et seq.). In order, while blowing, to bring the eye nearer the assay and readily observe volatile substances, it is well to use the following arrangement of the blowpipe. The smaller tube, carrying the platinum jet, is bent at a right angle; to the long tube is attached a rubber tube with a mouth-piece. plattner's blowpipe analysis. 11. The Fuel. In case of necessity a candle flame may be used for many qualita- tive blowpipe assays, but when a stronger flame is required, as in quantitative assays, peculiarly constructed lamps must be used, in which rapeseed oil, paraflSn, olive oil, a mixture of alcohol and turpentine, or illuminating gas are burned. Alcohol is poor in carbon and only suitable for a few blowpipe experiments. Eapeseed oil must be refined as the unrefined oil smokes. Olive oil bums very well, but is sometimes bad because the blowpipe flame is surrounded by a broad yellow envelope, and is then useless for assays in which the coloring of the flame by the substance under examination is to be observed. The form of blowpipe lamp now used for rapeseed or olive oil is the same as was proposed by Berzelius. The cistern. Fig. 7, is of tinned sheet-iron, about one hundred and sixteen milliro. long and coated with dark lacquer. Its section is shown by the front view, B. The socket, a, is twelve millim. long in the clear, and five millim. wide, and is filed slanting from right to left, so that the flame can be directed downward by the blowpipe when required. The cover, C, can be screwed tight over the socket, and for this purpose is pro- vided with a broad rim on which a leather washer soak- ed in wax is fastened with shellac. The oil is poured into a special opening. A, which can be like- wise closed with a screwed covei-. The wick is woven in a cylindrical form and is of cotton, like those used for Ar- gand lamps. It is pressed out flat and folded lengthwise so as to come fourfold into the socket, to THE FUEL. the width of which it must exactly correspond, fitting neither too loosely nor too tight, and its upper edge is cut parallel with the socket. The lamp itself is mounted on a brass stand and fixed on the brass rod by a screw, c. On the same stand is a brass ring, D, about fifty millim. in diameter, provided with a movable arm, and in it is a net- work of iron, or better still, platinum wire, which serves as a support for small porcelain vessels used in drying substances or heating fluids-- either over the free lamp flame or over the spirit-lamp. Since, how- ever, this arrangement is not well suited for heating a small platinum crucible or a thin dish of platinum or porcelain to a red heat over a- common spirit-lamp, there is a square hole in the movable part of the arm, d, into which the arm of an igniting ring, JE, can be inserted.. On the igniting ring is placed a triangle of platinum wire. For mixtures of alcohol and oil of turpentine glass lamps serve best, being made like an ordinary spirit-lamp, but provided with a socket and wick like the oil-lamp just described. Duflos has pro- posed a mixture of twelve parts of strong alcohol and one part of turpentine ; Pisani, a mixture of six parts by volume of alcohol of 85° and one part of turpentine, with the addition of a few drops of ether to clarify the cloudy liquid. Instead of the turpentine benzine may be employed ; four parts of alcohol and one of benzine giving a, strongly illuminating flame. The introduction of illuminating gas in many chemical laboratories has rendered its use very convenient for the blowpipe experiments, and the burner proposed by Bunsen is best suited for this purpose. Through ■ the neck, g, Fig. 8, which is connected with the gas pipe "by a rubber tube, the gas flows into the vertical tube, a, from below, issuing through a fine opening made by three slits meeting at a central point. Inside of the tube, a, the gas mingles with air entering through the side openings, s, so that if kindled at the upper end, it burns with a blue flame free from soot. While by this arrange- ment various experiments on the color- ing of the flame, the fusibility of sub- stances, and with borax and salt of phosphorus beads can be made, it may also be readily converted into a regular blowpipe lamp by slipping into a the Eraiill tube, I, so far as to cut off the access of air through s. The- 10 PLATTisTEK'S BLOWPIPJi: ANALYSIS. tube, I, is inclined at the top like the lamp socket, and has a slit ten to eleven millim. long and about 1.5 millim. wide. When the air is thus cut off the gas burns at the upper opening with an illuminating flame, which may be made as large as an ordinary lamp flame by regulating the access of the gas. Frick (Die Physikalische Technik, second edition, p. 48), has described an arranga- Tnent for glass-blowing which can be employed in a somewhat altered fonn for blowpipe examinations, Fig. 9 (natnral size). In this arrangement, which can only be nsed where illaminating gas is at hand, the lamp and blowpipe are combined. Over the exit tnbc, a, of an ordinary blowpipe a cylindrical case, iT, conical at one end, is slipped and fastened by a screw, s. Illuminating gas flows into this case through the neck, d, connected with the gas pipe by a rubber tube, g, and mingles with the air issuing from the aperture of the blowpipe jet, which should be as small as possible. The mingled gases pass through o, and when kindled form a long pointed flame. A few experiments will soon determine the proportions of gas and air required to produce an oxidizing or reducing flame. Besides the lamp for oil, etc., above described, a simple spirit-lamp, Fig. 10, is employed with advan- tage for examining many substances for volatile in- gredients, in small matrasses and thin glass tubes, and for fusing various substances with l)isulphate of potassa in a small platinum spoon, as well as for ig- nitions, etc. A larger spirit-lamp can be employed at home than on a journey, where the apparatus must be as compactly arranged as possible. III. The Blast and the Flame. The blast with the blowpipe is not produced by the respiratory ■organs, because then it could not be long sustained, and an unbroken current of air could only be kept up for a short time, but it is pro- duced by the muscles of the cheeks. The mouth is filled with air which is forced through the blowpipe by these muscles, and while blowing, the connection between the chest and the cavity of the mouth ■is closed by the palate, which acts at the same time as a valve, so long THE BLAST AND THE FLAME. li as the mouth is sufficiently full of air, and respiration is effected only through the nose. When, however, the tension of the cheek muscles, decreases, air is again admitted into the mouth through the throat during the act of expiration, and the cheeks thus inflated anew with- out interrupting the blast. Beginners generally commit the error of not closing the connection between the chest and the mouth at the right time, thereby allowing the lungs to work directly for a. longer or shorter period. That this style of blowing may be injurious to the health is. not to be doubted. Persons unaccustomed to the use of the blowpipe can learn to pro- duce a steady stream of air by taking care to breathe neither too fast nor two slowly, but just as usual, and in a distinctly audible way during the blast, and to continue this audible breathing until they can produce an uninterrupted stream of air of uniform force without the least straining. Success is not indeed immediate, but a few days' practice will cause improvement; and after a while such facility is attained that no further special attention need be bestowed upon the blast itself, and any fear of injury to the health is entirely dissipated It is impossible to prescribe the manner of holding the blowpipe while blowing, and the position of both forearms while treating an assay, since this depends upon habit; but the blowpipe can be held very securely and conveniently by taking the long tube between the- fingers of the right hand, but so that the inner joints of the index and middle fingers are above and the inner joints of the other two. fingers are below the tube, while the thumb is extended and supports the tube with the end joint, where the mouth-piece is attached. It is. soon found that the position of the forearms is more convenient when they only rest against the edge of the table than when the elbows are placed upon it. After learning to blow a strong unbroken current through the blowpipe there is no difficulty in producing a good flame by conduct- ing the current through the flame of a lamp, but in addition to thia a knowledge of the flame and its separate parts is necessary. On looking at the flame of the blowpipe lamp it will be observed, if the wick is not drawn out so far that it smokes, that it is composed of four separate parts. If a burning taper is placed beside it the same parts may be even more distinctly observed in its flame. Fig. 11 represents a candle flame, at the base of which is seen a small light-blue part, a b, surrounding the flame at this point, but narrowing as it recedes from the wick and entirely disappearing where the sides of the flame ascend vertically. In the middle of the flame is a dark cone, c, surrounded by the illuminating flame proper, the mantle, d, on the outer edge of which is a very thin, scarcely visible envelope, or veil, aei, which widens towai'd the tip of the flame anq is the hottest of its several parts. On holding a rather fine plati- plattkeb's blowpipe axalysis. nam or iron wire across the flame a^t f f, it is seen to swell most and to become white hot in the envelope, a e b, while in the darker portion, c, it scarcely glows. The cause of this is as follows : the r T' heat of the flame radiates back upon the tallow, wax, etc., f A and melts these substances, which are then sucked up f '*'' through the capillary force of the porous wick and brought into a temperature high enough to convert them into vapor. While these heated vapors are ascending the air enters from all sides and its oxygen effects the com- bustion, but this takes place only on the outer limit of the flame, forming the envelope a eb, which consists of carbonic acid and steam, and here too the flame is hot- test. In consequence of this high temperature the vapors behind this en\ tlope, consisting chiefly of the two kinds of carburetted hydrogen, separate into their conBtituent parts, and the separated carbon is made to glow, causing ['"iiilllllllll^^ the light of the flame and the existence of the part d. ^g- 11- As the free carbon approaches the veil, which is rich in oxygen, it is burned to carbonic oxide, then to carbonic acid. The dark cone in the flame consists of undecomposed vapors, since the heat of the veil decreases below and toward the middle of the flame. The air having access to the flame from all sides, at a b, produces a very perfect combustion, resulting in the light-blue portion ; but as there is not enough oxygen to convert the carbon into carbonic acid, only carbonic oxide is formed, and this causes the blue color. Of these four parts three can be as easily distinguished in the flame of the oil-lamp as in that of a taper, but the fourth, scarcely illumi- nating portion, is only to be perceived imperfectly and by careful observation. Only two of the parts are generally employed in blow- pipe assays ; the slightly illuminating envelope for oxidation and the illuminating portion for reduction. With the blowpipe, each of these parts may be made to work by itself, and we may therefore call the slightly illuminating envelope the outer or oxidizing flame, and the illuminating part the inner or reducing flame. Cases occur, however, where the slightly luminous flame oxidizes too strongly and the luminous flame reduces too strongly, in case a lively flame ia needed. Under such circumstances the blue part of the flame ia best employed. The manner in which the different parts of the flame can be rendered effective with the blowpipe will be particularly described in the following pages. THE OXIDIZING FLAME. 13 1. THE OXIDIZING FLAME.* On blowing into the lamp flame from one of its narrow sides so that the jet of the blowpipe extends about to the third part of the breadth of the socket, and the current of air, almost touching the wick, passes directly through the middle, a long blue flame, a h, is produced, which is really the same as a 5 in Fig. 11, at the base of the free flame, except tliat it appears in another form, and contains all the burning gases which are developed ; it here forms a slender cone, while there it only incloses the lower part of the flame. The hottest point is in front of the tip of this flame, where the most perfect combustion of the developed gases occurs. This hottest portion forms an envelope about the whole of the free flame, but here it is rather contracted to a point in front of the blue flame, surrounding the point of the latter with a cone of flame, which also extends to some length from a to c, and has a pale-blue color. As before mentioned, the hottest point is just in front of the tip of the blue flame at d, but it rapidly decreases in temperature toward c, and still more rapidly toward b. When a very high temperature is not required, the oxidation is best effected by heating the assay as far from the point of the blue flame as will admit of producing the necessary temperature (2-4 millim.). An essential condition in producing a pure 0. F. is a wick free from charred threads and hardened particles, and cut parallel with the slanting edge of the socket, since otherwise yellow streaks easily occur in the blue cone of flame, which are rich in carboniferous particles, and have a reducing efifect on the assay. When an assay is treated on coal a very strong blast should not be used, or else a part of the coal will be burned to carbonic oxide gas, which counteracts the oxidation. Molybdic acid affords the best material for practice in producing a pure O. F., as it imino(!iiitplT gives a brown glass with borax in an impure O. F. A moderate amount of it lo aidsulved in borax on a platinum wire in the 0. F., at three to four millim. dis- tance from the point of the blue flame, and yields a clear yellow glass, colorless when cool. On treating this glass directly with the tip of the blue flame for a short time, it becomes brown, and after blowing longer quite opaque, because the molybdic acid is brought with extraordinary ease to a lower state of oxidation, viz., binoxide of molyb- denum. Even a yellow streak in the 0. F. produces a brown color in the glass. The * Throughout the rest of this work the oxidizing flame will be designated by the letters 0. F. 14 plattneb's blowpipe analysis. •ooner a borax bead quite opaque with binoxide of molybdenum can be rendered cleat- again, so much the purer is the O. F. employed, provided it is effective enough. To be certain that a sufficiently strong O. F. can be produced it is only necessary to try to fuse the end of a platinum wire, O.I millim. thick to a globule. One end of the wire is bent at a right angle and held in the 0. F. with its axis corresponding exactly with the axis of the flame and so that it does nut vibrate. With a pure and strong flame a globule: will soon be observed to form suddenly, being larger in size the stronger the flame- employed. 2. THE REDUCING FLAME.* On blowing from the narrow side directly into the middle of the flame, so that the blowpipe tip reaches very little or not at all ^ -^^ into it, and the current of air. Pig. 13, passes- at a somewhat greater distance above the wick 1^ t^^^S:., *^*'^ '™^ -^^S- 12' th® whole of the flame assumes ^B ^^^^S the same direction as the stream of air, and ^K ^^^^f appears as a long luminous cone, a b, the end ^V ^^■i' of which, a, is surrounded by the same pale B Fig. 13. oblnish flame which can be observed with some care in the free flame, but which here extends to c. By thus blowing into the flame, the gases arising from the wick are burned,- and the carbon, separating in infinite particles, is rendered white hot,, and then, likewise consumed, producing, in common with the vapor of water already formed, the outer flame, which is plainly visible as far as c. A small part only of the dark cone is still visible, immedi- ately above the wick, and reaching to d, and between a and d, but somewhat nearer a, is the most active part of the flame. If this is- directed, for example, upon a reducible metallic oxide, so as to com- pletely surround it and cut oflT the access of air, the oxide will, owing to the tendency of the free carbon in the flame to take up oxygen,, either be entirely or partly freed from its oxygen, according as the oxide is easy or difiBcult to reduce, and the metal hard or easy t& fuse, or according as the reduction is effected on coal or in a solution in glass fluxes on platinum wire. A good E. F. is harder to produce than a good 0. P., and especial care must be taken that the assay be brought only into the most active part of the flame, and completely enveloped by it, while the- flame must be kept thus unchanged for a long time. Binoxide of manganese and the oxides of copper and nickel will serve for practice.. Binoxide of manganese dissolved in a borax bead on platinum wire in the O. F., give* an amethyst red glass, or when nsed in excess a black opaque bead, and the sooner the binoxide can be reduced to protoxide, and the bead thereby rendered almost colorless, * The letters E. P. will be used hereafter to designate the reducing flame. THE SUPPORT. 15 •o much the injro perfect is the R. F. employed. A similar bead made with oxide of eopper or nickel, and then shaken off, and treated on coal with the R. F., will soon prove whether the flame produced has the right effect or not. Both of these oxides can be reduced to the metallic state, the copper uniting to a small button, while the nickel comes to the sides of the glass in a state of cohesion. The sooner the glass be- comes clear and colorless, the purer and more powerful is the K. F. The blue flame, Fig. 12, a b, in consequence of the carbonic oxide which it contains, has also a reducing action, but it is far inferior to the luminous portion in its effects, and more accurate results are therefore always obtained with the latter in cases requiring perfect reduction. For tests by the non-luminous flame of the Bunsen gas burner Bee Ann. d. Chem, u. Pharm., 138, 257. ir. The Support. In treating an assay with the blowpipe flame, it must be supported on a body which, during the heating and fusion of the assay, will neither combine with it, nor cause wrong results in case the support is combustible. In many cases the assay is laid directly on such a body, but in many others this occurs indirectly, and the support is, therefore either a direct or an indirect one. a. The Direct Support. 1.^ Coal. Well-burned charcoal is especially suited for the support, as it helps to increase the heat when necessary. It is best made from mature light woods, as the pine and alder, and cut into parallelopip- edons, eighty to one hundred millim. long, and into square prisms,, according to the assays for which they are intended. Only those sides of the coal which show the edges of the annual rings are used.. Good charcoal for blowpipe assays cannot, however, be found every- where, nor is it always possible to produce sufficiently firm coal by- charring perfectly dry wood in vessels, and it is therefore advanta- geous, particularly for quantitative assays, to make coals of the requi- site shape out of not too fine coal dust with some binding material. Starch-paste, which Plattner has recommended as the best binding material, is prepared from one part by weight of starch-meal and six parts of water. The starch is stirred to a thin paste in an earthen vessel with a little of the weighed or measured water, and the rest of the water is poured, boiling hot, upon the paste, and the whole briskly stirred with a beater, until all the meal is converted i^to- paste. To prepare blowpipe coals, this paste is rubbed in a porcelain mortar with successive additioas of charcoal dust, until the mass ini 16 plattker's blowpipe analysis. the mortar becomes too tough for aaiy further admixture of coal dust. Enough of coal dust is then kneaded in with the hands to render thp whole mass stiff and plastic, and it is then worked thoroughly. Fror^ tills mass various forms of blowpipe coals can be made, as will be here- after described. When made they are allowed to dry gradually and thoroughly, and are then heated to a low redness in a covered cruci- ble, so as to char the binding material. Small pieces can be ignited in a covered porcelain crucible, over a spirit-lamp with double draught or a gas-lamp ; when preparing larger pieces, or a sufiBcient supply of the coals, it is best to choose a spacious crucible of clay, or stout sheet-iron, which is covered with a close-fitting cover, and heated in a small wind furnace with a very weak draught, between glowing charcoal, or in some other moderately strong fire. The charring is complete when combustible gases cease to issue from beneath the cover, and when, on raising the cover, the coals in the upper part of the crucible are perceived to be at a low red heat ; the crucible is then ■removed from the fire and allowed to cool with the cover on. The coals are of the proper firmness and ring like ordinary good charcoal when thrown on the table. The various forms of coal to be prepared, are as follows: for assays where no regard is had to the coat, and for refining copper, small coals of a flat dish-like shape are made. In producing them, the mould to be hereafter described for the clay capsules. Fig. 27, is used, and only a special stamp is needed, which is best made of boxwood; the moulding part has the form of the segment of a sphere, con- structed with a radius of twenty millim.. Fig. 14. After strewing the mould. A, Fig. 37, with coal dust, a strip of paper about fifty millim. long and five millim. wide is laid over it, the cavity filled with the prepared mass, and this pressed to- gether with the stamp. Fig. 14, which has been dipped in cou] dust. By means of the two projecting ends of the paper the dish-shaped coal is lifted from the mould, and then set aside to dry in a moderately warm place, after which it is ignited as before mentioned. Fig. 15 shows such Pig. 15. a coal. Small coal crucibles are very well adapted for decomposing com- pounds of silicic acid as well as for quantitative assays. The cruci- ble mould. Fig. 29, to be hereafter described, is employed in making them, and the metallic plug is replaced by a wooden one. Fig. 16, the diameter of which at a J is twenty-seven millim. and at c nine millim. The iron mould is first pressed full of the mass, which has previously been rolled into a ball and dipped in charcoal dust, and then the 3i% THE DIRECT SUPPOET. 17 wooden plug, Fig. 16, is dipped in coal dust and set upon it, so tliat the part c conies exactly in the middle of the mass, which is then pressed together. After removing the plug by turning it gently, the mould is taken apart in the way to be described in making clay crucibles, and after cutting off the project- ing edges on the two opposite sides, the coal is so far ready that it requires only to be ried and ignited in a closed yessel. The coal crucible in the natural size is shown in Pig. 11. The depth of the cavity in such a crucible need only be six millim., and when a deeper hole is necessary for any quantitative assay it can be bored out and widened as required, with the help of the coal borer to be described hereafter. In order to facilitate the handling of these coals, capsules, and crucibles, a cylinder. Fig. 18, is used as a support for them, which is sixty to sixty-five millim. high and twenty-five millim. in diameter, being made of any mass which is easily worked, fusible with difficulty or not at all, and is a poor conductor of heat. It is provided at each end. A, B, with cavities corresponding to the size of the coal to be supported. Pumice-stone or porous burnt fire- clay are suitable materials. To prepare a cylinder from fire-clay the dry powdered clay is well mixed with an equal volume of coarsely-beaten charcoal and then made plastic with water. The cylinders formed from this, either by hand or with the aid of a special mould, are allowed to dry thoroughly and then ignited in a loosely covered crucible among coals. In quantitative blowpipe assays when roasting ores in clay capsules, and when fusing lead, bismuth, tin, and many nickel and cobalt assays in clay crucibles, a hollow coal is required, which is secured in an especial coal-holder, and the cavity of which must be covered with some suitable coal, also hol- lowed out, when a fusion is to be performed. For these coals a mould of hard wood can be used, constructed as follows : the main part of the mould, G, Fig. 19, consists of four pieces which fit each other exactly and are held together by a brass ring, which can be drawn more or less tight by the screw g. These four pieces surround a prismatic space forty millim. high and thirty-five millim. square. A and B are stamps, ttie rims of which, a b and c d, have a diameter just equal to the distance between two of the strong brass pms fastened opposite one another vertically in the four pieces of the mould C, and which serve to bring the stamps A and B exactly in 18 plattner's blowpipe analysis. the middle of C. The projecting portion, e, of the stamp A is eighteen millim. long and has a diameter of twenty-two millim. at the top ; the part, /, attached to £ at c d, forms a segment of a sphere which has a breadth of twenty- two millim. at its junction with the rim, and is nine mil- lim. thick. D is a prism fitting exactly into C, and serving as a bottom in mak- ing coals for roast- ing and fusions. E is a prism seventeen millim. high, which is laid upon D when only coal covers are to be made, and hence also serves as a bottom. When coals are to be made in this mould a piece of paper corre- sponding to the size of the mould is laid on the bottom prism, the side surfaces are rubbed with a little coal dust, the empty space pressed full of the coal mass, and the requisite stamp, the moulding part of which has likewise been dipped in coal dust, is pressed firmly into it, turning the stamp a little at the same time on its axis and then drawing it carefully out. By loosening the ring and removing it from the mould the separate pieces can be easily taken away by sliding each one downward from the moulded coal, which is then ready for drying and charring the binding material. Such coals must be dried with care, as they are liable to crack if put immediately in a very warm place, if is a coal as it is used, when secured in the coal-holder, for roasting in clay capsules and fusions in clay cruci- bles, and (? is a coal which serves to cover the cavity in the former coal during fusions. Both coals are bored through shortly before use, the former on the side, the latter in the middle of the hollow, as will be described in the proper place ; the cavity in F can also be made deeper and wider with a coal-borer, as required.* * Hirsehwald (Berg- u. Buttenm. Zeit., 1876, No. 18,) has recommended graphite or gas coke for such coals for fusion assays. In using this material illuminating gas is most suitable, with an arrangement similar to Fig. 9, or a Bunsen burner arranged in like manner with a rubber bellows. Also, the channel for the flame is not made at the side but vertically under the crucible, and the gas blowpipe or the burner stands below this channel. It is ihen unnecessary to use the coal-holder, Fig. 53, as the coal can rest simply on a ring above the flame. THE DIKECT SUPPORT. 19 When there is a total lack of charcoal suitable for qualitatiTe as- says, in which long pieces in the shape of a parallelopipedon are gen- erally needed, they can also be made in the above manner, by means of the mould shown in Mg. 20. In this case, however, if the coal dust on burning leaves a considerable amount of ash, it must first be purified by digesting it in aqua regia and then washing it wel! with hot water. The coals, about eighty millim. long, twenty mil lim. wide, and from ten to twenty millim. thick, are made in the following way : the main part, A, of the mould, which consists of four pieces, abed, held together by a brass band, H, and surrounding a space «ighty millim. long, twenty-one millim. wide, and thirty millim. high, is placed upon a firm, even support, and a piece of wood five millim. thick, corresponding in length and width to the inside of the mould, ^^s- ao- ^mI is laid in it for a bottom. This bottom is covered with a piece of paper of the same size, the empty space filled with as much of the coal mass as is needed to make a coal of a given thickness, and on this is placed another piece of paper, the size of the first, and finally the moulding part, B, having a section twenty-*ne millim. square, is inserted and the mass pressed together. This done, the screw, /, is turned enough to loosen the brass band, when the four pieces, abed, are drawn out separately and the coal, after being freed from the ad- hering papers, is ready to be dried and charred. By holding the mould in both hands and pressing down the piece B with the thumbs, the moulded coal may be removed without taking the mould apart, but its interior surfaces must be wiped off every time before moulding a new coal, lest particles of the mass should adhere to them, and the easy separation is promoted by rubbing the sides of A with a little coal dust. The binding material of these coals must likewise be ■charred when they are perfectly dried. These long coals, as well as «ut pieces of charcoal, after being used, are best cleansed from the coats, etc., which may be on them, and prepared for further use, by means of a file or rasp. Since good coal tor qualitative tests is scarce, Foster has recommended the use of prisms of hard-burned clay shaped like the above-described long coals. On one or both faces of the clay is made a ci^vity to receive a coal capsule, Fig. 15, or a bit of charcoal fitted into it, on which the assay piece is laid, the surface of the clay being first coated with soot over an oil flame. On this black ground coats of vo- latile bodies are well observed, and a new layer of soot makes the clay ready again, although only a limited testing of such coats could be further performed. 20 plattnee's blowpipe analysis. 2. Platinum in tlie shape of wire, foil, and spoons. — The best plat- inum wire for qualitative use is about 0.4 milUm. thick, and is cat into pieces about forty-five millim. long, with a loop at one end. Fig. 21, A. This serves as a support for borax and salt of phosphorus beads, which can thus be very conveniently examined, and are quite free from the false play of colors that often appears on coal, through the position of the bead on the black support. In examining metallic alloys, however, and in reduction assays where easily fusible metals separate, platinum wire cannot be used, but coal must always be used as a support. When in use the wire is either fixed in a soft cork or secured in an especial holder. Pig, 21, B, which also serves as a case for several wires. To prevent injury to the wires from the screw, holders are used in which the wire is inserted into the middle of two slits crossing each other at right C angles ; the latter are then shut tight by a band I which is thrast over them and arranged to screw up and thus hold the wire. In Fig. 22, the upper part of such a holder, with the baud, a, is represented in the natural size. The loop is most readily cleansed from adhering substance by warming it in a test tube with dilute hydrochloric acid, and then rinsing it with distilled water. Besides several slen- Ider wires there may be another, 0.6 millim. Fie. 21. thick, and likewise bent to a loop at one end, Fig. 21, C, which is of advantage in testing for tantalic and tungstic acids, etc., where the substance must be fused with alkaline carbonates. It is either held with the fingers or fastened in a small cork. The use of platinum foil in qualitative examinations is very limited. The thin rolled foil is cut into strips about sixty millim. long and fifteen millim. wide, and when in use the free end is either held in the forceps or thrust into the end of a long piece of charcoal, between the yearly rings. Metallic substances in the reguline state, or such as are easily reduced and fused during the blast, must not be treated on platinum foil, since they combine with it and render the correspond- ing spot useless. The foil is generally used to fuse substances con- taining manganese with carbonate of soda, which becomes bluish- green on cooling, from the presence of manganate of soda, and thus the presence of manganese is indicated. THE DIRECT SUPPOET. 31 A platinum spoon is necessary for many assays, and it is, in fact, advantageous to have two, one about fifteen millim. in diameter, Fig. 23, and a smaller one, Fig. 24, about nine millim. in diameter. On using the larger spoon, the handle, which must also be of platinum, is inserted mto a small wooden holder, or into a piece of coik ; the smaller spoon is held fast by the handle with the forceps. The larger spoon is used for fusing certain substances with bisulphate Fig. 24. of potassa, for heating the gold obtained from n quantitative assay, and for other purposes; the smaller one, on thfl other hand, serves only for the fusion of certain substances with saltpetre. If it happens, after a fusion with saltpetre, that the spoon does not become clean by dissolving the fused mass in water, on ac- count of adherent particles of metallic oxides, it is only necessary to melt a little bisulphate of potassa in it over the spirit-lamp, and then to cleanse it with water. A thin platinum dish, about thirty millim. in diameter, and ten millim. deep, is of advantage for decomposing many combinations of fluorine by sulphuric acid, as well as for igniting filters, the precipitates on which are to be weighed or further examined. A thin piece of platinum foil is used to cover the dish more or less during ignition when required. 3. Glass tubes and matrasses. — For recognizing in minerals, ores, and products, substances which become volatile at a high temper- ature by access of air, tubes recommended by' Berzelius, are used, from one hundred and twenty to two hundred millim. long and about six millim. in diameter, which are open at both ends.* The assay is placed near one end, which is then inclined downward, while the other end is warmed over a spirit-lamp, so as to create a draught through Mie tube, and then the spot where the assay lies is to be heated. When but little heat is required for driving off the volatile substances, or those which become volatile, the free flame of the spirit-lamp is used; but if otherwise the blowpipe flame must be employed. The tube is inclined more or less according to the strength of the draught desired. The volatile substances formed during the roasting "either pass off as gases, or are sublimed upon the interior of the tube, and can thus be easily recognized. A small sup- ply of these tubes is to be kept, and when one has been eni- * These will hereafter be designated as open tubes. 23 PLATT2»-ER'a BLOWPIPE ANALYSIS. ployed it is broken off by filing a notch above the spot~^^~ used and then cleansed and kept for another assay. WM When it finally becomes too short, one end is closed by I ;1 melting, and it will still serve for a sublimation test. I 1 To prevent the assay from falling out of the inclined i' 11 tube before it adheres to the glass, Berzelius recom- I '1 mends bending one end of the tube at an obtuse angle, I « Pig. 35. The assay is then laid in the angle a, and /' m the tube inclined as required. f -^M A matrass is a tube closed below and blown into a ^^0^ bulb. Fig. 36, A, and is sixty to seventy miUim. high. ^s- as. | It is used for ascertaining the presence of water or any volatile body in a substance, or in case a substance which decrepitates strongly ia under treatment and is to be further examined. The matrass is heated over a spirit-lamp, and when used for another assay must be cleansed with dilute acid or water and thoroughly dried, which ia accomplished very simply and rapidly by warming it well over the spirit-lamp and sucking out the water in the form of vapor through a slender glass tube that reaches into the bulb of the matrass. Fresh air thus enters, and by continued suction removes every trace of water in the form of vapor. "When combustible bodies, like sulphur, arsenic, etc., are to be sub- limed from a mineral, ore, or product, a glass tube. Fig. 36, B, five to six millim. wide and seventy to eighty millim. long, is used, which is melted together at one end, but is not enlarged, so that neither com- bustion nor partial oxidation of the combustible bodies can take place, as would be caused by a slight current of air.* A small supply of matrasses and closed tubes should also be kept on hand. 4. Capsules and crucibles of fire-clay.— The capsules are used for roasting minerals, ores, and metallurgical products, which are to be quantitatively examined for the metal in them, as well as for roasting substances consisting of a mixture of earthy parts with metallic arsen- ides and sulphides, which are to be examined only qualitatively for the earths or metals, as for example, ores dressed on a large scale. These capsules are made in the following way : First a stiff paste is made of ' Such tubes will hereafter bo designated as closed tvhes. THE DIKECT SCPPOET. 23 elutriated fire-clay. Then the moulding surfaces of the boxwood mould, Fig. 27, A B, of which A has a width of 20.5 millim., above, and a depth of 7 mil- lim., while B is constructed on a radius 0.8 millim. smaller, are rubbed with oil and a strip of thin pa- per, fifty millim. long and five millim. wide, is laid over the cavity of the mould. A ball of the soft clay mass, about twelve millim. in diameter, is then placed on the middle of the paper and pressed firmly I J^ ^^ into the cavity with the fingers, and after plac- l ^^^^^^^H ^^S ^ on a firm level support and holding it with ^^WSm^^^M one hand, the convex part, B, is pressed with the I Fig. 87. other hand in a vertical position directly into the middle of the clay as far as necessary, being turned a quarter of a revo lution on its axis. By this means the superfluous clay is pressed out at the side, and B can be easily drawn out by turning it carefully. As much of the clay which has been forced out is cut off as is neces- sary, and then the edge of the capsule is examined, to see whether it is sufficiently thin all around, or whether one side is thicker than the other. Fig. 28 shows a section of such a capsule, in the natural size, which must be only 0.8 millim. thick before it is burned. If it is too thick on one side, £ must be again pressed into it, rather more on the thick side, or exactly in the middle if it is too thick all around. After carefully withdrawing the convex piece, B, and cutting away the superfluous clay, one end of the paper «trip is taken in one hand and the other end in the other hand, and the capsule cautiously lifted from the mould. When, through want of practice, the capsules become disturbed in removing them from the mould, they can be restored to shape by pressing them separately with the fingers against the convex piece, B, on all sides, before they have become dry in the air. During this operation the paper strips separate of themselves, and the basins are set aside to dry in a warm place, after which they are put in a vessel of baked clay, which is set uncovered in a potter's baking furnace, or in some other fire, where they can be brought to a red heat, as in an assay muffle, which has just been fired up, or in a simple coal firei They may also be baked in a platin urn crucible over a spirit-lamp with a double draught, or a gas-lamp. These basins shrink a little iu baking, but remain just the size required. 24 plattn'ee's blowpipe axaltsis. Fig. 89. The crucibles are used for quantitative assays. They are formed in a brass mould, consisting of a plug and a box, the latter being composed of two parts held firmly by a ring. Fig. 29 represents this instrument, and Fig. 30 a prepared clay crucible. A is the plug, with four conical openings at a to let out the excess of clay put into the mould. The moulding ^ part has a diameter of nineteen millim. above, and is fourteen millim. long; B is the box, consisting of two halves, fitting exactly to- gether and forming a blunt cone. At S, on the inner side of each half, which is about 0.8 millim. from the plug all around, the corners are somewhat blunt, so that slight cavities are formed in the box at two opposite points, and when moulding crucibles these become filled with clay, thus preventing the crucible from turning when the plug is turned. G is the binding ring into which the box is slipped, so that it can be easily lifted out, and the lower surface of the- box and ring are in the same plane. To mould a crucible, small balls are formed with the fingers fi-om a stiff paste of water and elutriated fire-clay, each containing rather more than is needed for a crucible, and they are then allowed to dry in the open air, until they can only be pressed between the fingers with difficulty. The moulding surface of the box and plug, and those faces which are to lie upon one another, are then rubbed with a very little oil, and the mould, with the ring, is placed upon the anvil, which rests upon some elastic support, such as a wool- len cloth folded several times. The clay ball is then put into the box and the plug driven in so far, in a vertical position, with a wooden mallet that the projecting rim, c, rests upon the edge, d, of the box. The plug is then lifted out by turning it, which also removes the superfluous clay; the box is pressed out of the ring from below, and while one half is held between the fingers of one hand and the other with the other hand, the halves are separated in succession from the moulded crucible. This is best done by sliding one half down a little loosened on the other half so as to loosen the crucible, and then the first half is pressed gently against it while the other half is in the same manner and entirely detached, when the crucible can be removed in a perfect state from the first half. The crucibles, after being freed with a sharp knife from the two projecting bits of CAPSULES AND CRUCIBLES OF FIRE-CLAY. 25- clay, are set aside to dry, either at first in the fresh air, or else directly m a warm place, and are then baked in the same way as the olay capsules. No time should be spared in making day capsules, since it is an essential condition that they should be quite thin, and the clay must not be worked up too hard or too soft- If too hard the capsule is moulded with difficulty, if too soft it can seldom be lifted from the mould without tearing. The consistence proper for the clay mass is, however, very soon learned.^ When the mould is new the oil rubbed on the surfaces generally soaks into it, and the moulded basin cannot be taken out without tearing it, and it is well when using a new mould to rub it several times with oil and let it soak in thoroughly. A must likewise be rubbed with less oil than B, since otherwise the basin may easily adhere to B, and be lifted out with it. 5. Bone-ash. — It is used to make small cupels upon which aurifer- ous and argentiferous lead obtained from blowpipe assays is cupelled. Two grades are used, the sifted and the elutriated bone-ash. Bones of quadrupeds are thoroughly calcined, the perfectly white- portions, free from coaly parts, are selected, broken up and stamped in a mortar until the powder will go through a fine hair sieve. This yields the sifted bone-ash. A portion of the sifted bone-ash is put into a large beaker glass, which is then nearly filled with pure water, and the whole stirred with a glass rod and afterward allowed to stand a moment. During this time the coarse particles settle, while the finer ones remain for the most part suspended in the cloudy water, which is then carefully decanted into another beaker and allowed to remain quiet until the fine particles have settled, when the most of the water is poured ofi". As some fine particles settle with the coarse the elutriation should be repeated until the water is only slightly cloudy. The fine elutriated bone-ash is then brought upon a filter, so that most of the water flows ofi", and is then dried and heated to redness. Both sorts readily absorb moisture and must be kept in glass-stopped bottles. The coarse powder remaining from the elutria- tion can be again pulverized and elutriated. The manner of making the cupels will be given in the description of the cupel moulds, under instruments. b. The Indirect Supports. 1. Soda-paper. — In the quantitative determination of several metals the weighed and prepared assay must be wrapped in something which withstands the first action of the blowpipe flame, so as to prevent the particles of ore from being blown away. Harkort * found fine letter- paper, soaked in a solution of carbonate of soda and dried, to be most * Prohirkanst mil dem Lothrohre, Freiberg, 1827, vol. 1. p. 34. 26 plattxer's blowpipe analysis. suitable, and this paper may be used with advantage for wrapping up bulky charges in qualitative analyses also; but since letter-paper fre- quently contains foreign substances, such as oxide of cobalt, fine filter- paper should then be substituted for it. Thin strips of both sorts of paper are drawn through a solution of about 25 grm. of crystallized carbonate of soda, free from sulphate, in 50 c.cm. of pure water, which is put in a shp.llow vessel, such as a porcelain dish. The strips are dried slowly in the air, or in a moderately warm place, and are then cut into pieces thirty-five millim. long and twenty-five millim. wide, and kept for use. When used they are made into small cylin- ders, as will be described hereafter. 2. A mixture of seven parts charcoal and one part fire-clay. — It is used to line the small clay crucibles in quantitative tin and lead assays, and is made thus : Seven parias of very fine dry charcoal powder and one part of elutri- •ated fire-clay are weighed out, the latter is thoroughly mixed with water in a shallow dish, and the coal dust ''^#*' j is then poured in and kneaded with the clay water ^g-3i. j to a paste, which is allowed to dry in a warm place, and afterward rubbed to powder again, in which state it is kept for use. To line a clay crucible with this mixture, a small quantity is made into a paste with water in a small porcelain dish, and part of it rubbed inside of the crucible, so as to lie about three millim. thick at the bottom and thinner on the sides, especially about the edge, as is seen in Fig. 31. While part of the water soaks immediately into the baked crucible another portion remains m the paste, which is still so soft that it may be rubbed smooth on all parts, with the dry plug of the crucible mould. Fig. 29, A. The lined crucible is then thoroughly dried over the free lamp flame. V. Instrwments, small Vessels, and other Objects used in Blowpipe Analyses* 1. A delicate balance. — For quantitative assays this must be ca- pable of indicating with precision an additional 0.1 milligr. when loaded with two decigr., and should be so made that it can be easily Bet up and taken apart. Fig. 32 is a perspective view of such a bal- * Blowpipe instruments are accurately made by S. HawkiL=i, Stevens Institute Hoboken, N. J., ami by Williams, Bronne A- Flarl, PhiladelrihiM. INSTliUMENTS, ETC., USED IIT BLOWPIPE ANALYSES. 27 I Fig. 38. ince, as constructed by A. Liiigke, for blowpipe assays. The beam^ which is one hundred and eighty millim. long, moves on carnelian plates, and all of the brass work is gilded. The tongue from a to h is one hundred millim. long, and the cords, including the hooks, one hundred and forty millim. The scale-pans attached to the cords are thirty-three millim. in diameter, and very slightly concave, and on each of them stands a small gilt pan fifteen millim. wide and four millim. deep, to receive the objects to be weighed and the weights. The two larger pans, g, g, each twenty millim. in diameter, are used for weighing bulky substances. The balance is set up on a low box, in- side of which it can be packed, together with other instruments, when taken apart. On the lid of the box is screwed a stout upright brass rod, to which the balance is secured by a screw, and the beam is raised by a fine silk cord which passes over three pulleys, c, d, e, the lowest one, e, being separately screwed in. This cord is attached at one end to the support of the beam, and at the other end to a knob, which is fastened in the box, and can be turned so as to wind up the cord. The brush, /, fastened on a movable brass arm, serves to prevent unneces- sary swinging of the tongue. When the balance is to be used for de- termining the specific gravity of minerals, metallurgical products, etc.,. the necessary pans can be made for it. It is vei"y advantageous to protect the balance against dust and currents of air by a glass case. Lingke has constructed one for this purpose, which can be folded up. and transported on a journey. ;28 plattxer's blowpipe analysis. ■* H-.J) 2. Weights. — The fittest weight for blowpipe assays is the gramme used by Harkort. One decigramme = 100 milligr. serves as the assay centner (hundredweight). 3. Blowpipe assay scale, or Plattner's scale. — The silver button obtained by a blowpipe assay of 100 milligrm. = 1 assay centner, of an ore poor in silver, is so small that its weight cannot be deter- mined on the balance, and Harkort conceived the idea of measuring such buttons on a scale con- structed for the purpose. This scale is foimded on the principle that the weights of the metallic spheres are proportional to the cubes of their diameters, and that these diameters can he accurately compared together iy means of two fine convergent lines, between which the spheres are laid. Plattner, following Harkort's plan, prepared a scale, which is figured in the form formerly made by Idngke in Fig. 33, but this form is not adapted for universal use.* The scale is made of ivory and the lines, a b, a c, diverge 1 millim. at a distance of 156 millim. To determine the weight of a silver button, it is placed with a pair of fine forceps between the two convergent lines, ab,ac, and then, with the aid of a magnifying-glass, moved into a position where the lines are just tangent to its sides, the eye being held vertically ovar it to avoid any parallax. On the left hand are the numbers of the transverse lines, and the figures on the right give the Loths in a centner (110 lbs.), when one assay ctr. of ore was used. As now constructed in Freiberg, these scales show at once by the right-hand figures the percent- age of silver in an ore; in case of gold buttons, the percentage must be obtained from the tables given below, and these tables may also be used for learn- ing the percentage of silver when the bead has been measured on the old-fashioned scales, represented in Fig. 33, and the right-hand figures of which run from 122.5 down to 0.0009. In using the table *£.. A" Fig. 33. • Although no longer made by Lingke, the old form of Plattner's scale may be met with. The modern form is similar in all re- spects, except that the right-hand column of flgnres shows the percentage of silver directly, the figures running down from 3.48 to 0.00003. Sjo the following table. INSTRUMENTS, ETC., USED IN BLOWPIPE ANALYSES. 23 the position of the button as regards the transverse short lines la noted, and the corresponding percentage of silver or gold in the ore is read off from the table. No. of the TranBTeree . Line. Percentage of Silver. No. of the Transverse Line. Percentage'of Silver. Percentage of Gold. 5o 3.48011 26 0-48933 I .06523 49 3.27545 25 0.43501 0.94609 48 3.07898 2.89053 24 0.38487 0.83784 47 23 0.33874 0.73741 46 2.70992 22 0.29644 0.25783 0.64534 45 2-53700 21 o.56i34 44 2.37160 20 0.22273 0. 48485 43 2.21545 19 . 1 9096 0.41570 42 2.06268 18 0.16237 0.35346 4i 1.91882 17 0.13678 0-29776 4o 1-78182 16 0. [i4o4 0.24824 39 i-65i49 i5 0.09396 0.20455 38 1-52769 i4 0.07639 o.i663o 37 I-4I022 i3 0.06116 0.13296 36 1.29894 12 o.o48ii 0.10473 35 1-19368 II o.o37o5 . 08066 34 I -09426 10 0.02784 0.06061 33 I -ooo52 9 0.02029 0.04418 32 0.91229 8 0.01425 o.o3io3 3i 0.82941 7 0-00955 0.02079 3o 0.75170 6 0.00601 o.oi3o9 29 0.67903 5 0.00348 0.00757 28 0.6III6 4 0.00178 O-00388 27 0.54799 3 0-000752 0-00164 2 0.000223 O-00048 I . 000028 0.00006 It is scarcely necessary to remark that in reckoning the percentage of silver only two decimal places need be used, and when the next decimal figure is above five the preceding one is increased by one ; thus, in case of line 23 for 0.33874: read 0.34:. Should the button come about midway between two of the transverse lines the percent- age is found by simply dividing the sum of the percentages corre- sponding to these lines by two. Should it, however, lie nearer one line than the other the space between the lines may be divided into thirds by the eye, and if the button lies in the lower third add one-third to the percentage corresponding to the lower line, or if in the upper third subtract one-third from the percentage indicated by the upper line. The number of troy ounces in a ton of ore may be readily reckoned after obtaining the percentage of silver or gold, either from the scale or by weighing, by noting the fact that one per cent, of a ton of 2000 lbs. is 291.66 ounces, and of a ton of 2240 lbs., 326.65 ounces. The use of the scale has its limits, and it is easy to see from the 30 plattnek's blowpipe analysis. above table that with the increase of weight there is a greater differ- ence for each transverse line, so that there must be a point np to which the determination of the weight on the scale is exact, and be- yond which it is better to weigh directly on a delicute balance. The limit depends chiefly upon the amount of practice in placing the but- ton properly with the help of a glass. Experience shows that with ores containing less than 0.5 per cent, the weight of a single button can be more correctly determined on the scale than by the balance, but in a duplicate assay on ores of 0.3 per cent, and upward, the bal- ance gives more accurate results ; for ores of over one per cent the weight of a single button can always be more exactly determined by weighing than by measuring, and when duplicate assays are made the difierence is still greater. The accuracy of the results obtained by measuring gold beads has about the same limits as in the determina- tion of silver beads. The results obtained during practice in measuring the buttons may be controlled by determining the weight of several buttons by meas- urement, and then actually weighing them all at one time, after thor- oughly cleaning them between moist paper and the anvil. The ivory scale, described on p. 28, affords a very simple means of measuring buttons, and gives very accurate results in the hands of an experienced operator. By immersing the silver buttons in dilute sulphide of ammonium they become blackened, and then their out- lines can be more distinctly seen upon the ivory scale. Unless, how- ever, the operator has become quite expert in its use, by controlling his results with weighed buttons, as before recommended, it is liable to give inaccurate values, and a certain personal error is also apt to occur in the readings, since one person may obtain too high results and another too low ones with the same instruments. Influenced by a desire to invent an instrument which should yield more certain results than could be obtained by Plattner's scale, Chas. C. Eueger has devised the apparatus shown in Fig. 34, A and B. This apparatus is described in the Berg- und HMtenm. Zeitung, 1869, No. 29, as follows : Fig. 34, A, shows a horizontal projection of the apparatus; Fig. 34, B, a section through CD. Upon the upper surface of the plate, a, is festened a female screw, b, into which the mi- crometer-screw, c, provided with a graduated circle, exactly flts ; e is a socket, which serves to hold and guide the cylinder of the small slide, g. The slide and micrometer-screw touch at r. The other wedge- shaped end of the slide rests on the plate at a, and has a perfectly plane surface, perpendicular to a. Against this presses the likewise plane face of the projection attached to the end of the index lever, /; rueqbb's appabatus. 31 h is a epring, which presses the short arm of the leyer against the slide. Around the sides of the plate, a, is a rim, serving to prevent the button from rolling ofiP. Upon this rim, at i, there is a fine line. ^^ ^ W a '& [QO~l= ..^M a -^^-O^^^ Fig. 34— A Fig. 34— B. with which the point of the index lever coincides when the faces of the slide and lever are exactly parallel to each other, i. e., touch each other, if nothing is interposed between tbem. The graduated circle, m, upon the micrometer-screw can be set in any position and secured there by means of the screw, n. The periph- ery of the circle is divided into hundredths, and the index, o, should point at on the circle when the lever coincides exactly with the line i. The latter condition is securec' by using a strong magnifying- 52 PLATTNEE'S BLOWPIPE ANALYSIS. glass. "When the apparatus has been thus arranged the micrometer ■ screw is drawn back, whereupon the spring, v, presses back the slide, and the spring, h, the shorter arm of the lever. The point of the lever at the same time moves away from i, until finally the longer arm rests against the pin iv. If the screw iff still farther withdrawn the face of the slide recedes more and more from that of the lever, so that a button may be placed between the two. The screw is then turned in the opposite direction, until the point of the lever again coincides exactly with i, when the two faces are once more parallel, but separated by an interval corresponding to the distance between their points of contact with the button. This distance is read off in complete revolutions and hundredths of revolutions of the graduated circle ; the complete revolutions being indicated by the position of the face of the slide with reference to the lines on a, and the hun- dredths given upon the circle. The interval between two adjacent lines of the scale on a corresponds to two revolutions of the screw. It is advisable to measure the button in several different posi- tions, so as to obtain an average value. To avoid any error arising from possible inequalities of the surface, a fine line is drawn upon the surface, a, in the direction of the axis of the screw, and upon this the button should always be placed. The accuracy of the measurements depends immediately upon the proportion between the longer and shorter arms of the lever. If the line, i, and the point of the index lever are fine and sharp enough, and the dimensions of the instrument made to correspond with tiiose in the figure, there will rarely be a difference of one division on the circle, upon repeating the measurement. In Rueger's instrument the micrometer-screw makes about five revolutions to the millim., and therefore advances -J- millim. by one revolution, or -g^ millim. for each division of the circle ; the results obtained by the inventor seldom varied more than ^^ millim. Such a result is all that can be de- sired, when it is considered that the irregular shape of even an apparently quite round button may lead to five or six times that difference. The apparatus is made by the mechanician Kulle, in Clausthal. Another apparatus for measuring buttons has been devised by L. Kleritj, and is described in the Berg-und Satienm. Zeit^ 1870, Nos. 1 and 2. It is represented in Fig. 35, A, B, G. KLUKITJ'S APPARATUS. SECTION THROUGH Q.}} 2E .^_^ P Pig. 35— C, 3 34 PLATTinBE'S BLOWPIPE ANALYSIS. The instruTient consists of a brass support, or plate, a b, which rests upon two feet on the side a, and upon one foot on the side b. Upon this plate is fixed a guide, c, having a trapezoidal section, and upon this guide moves the wedge, /^, which is provided with a corre- sponding groove and slides along the vernier, d e. Against this wedge press the slides, h, t, which move in two guides screwed to the support, and are placed at a right angle with the edge,fg. The slides end ic. two facos, or jaws, between which the body to be measured is placed. The glides, 7i and i, are pressed against fghj the spring k, but be- tween i and i is interposed a shorter arm, I, which turns about a ver- tical axis, and is firmly joined to the longer arm, m, below the instru- ment. The latter is provided at n with an index, serving to set the instrument. Upon presfcing the wedge, fg, in the direction of the arrow, the aim, I, must move from right to left, since h and i are pressed against it from left to right. To reinforce the spring, k, a slit is made in the plate, in which the pin, 0, fixed into the slide, h, can move, and this pin is governed by the spring, p, working like k. When the of the wedge coincides with on the vernier the two lines upon the plate and the projection n should also coincide. To measure a button the wedge is pushed about half way out, and the slide, i, moved somewhat toward the left by means of the pin, gj the button is then placed between the jaws, and the two lines on the index at n made to coincide by means of f g. In this instrument the dis- tance between the two parallels assumed by the side ^ at and 30 is three millim., and the reading for the position in Fig. 35, B, would be 0.86 miUim. It is very easy for the mechanician to determine the iufairval be- tween and 10 on f g, as he need only place a wire or any object, known to be exactly one millim. thick, between the jaws, bring the two lines together at n, and prolong the zero line of the vernier. To use the instrument for determining the weight of silver buttons Kleritj has prepared tables, which are here copied in part, and in which the weight of the button, or the percentage of silver obtained from one blowpipe assay-centner is given for any button, from 0.01 to one millim. in diameter. The formulas by which this table was calculated are given in the number of the Berg-und Hilttenm. Zeit,, above referred to, and we will here only remark that theoretically the weight of a body is expressed by the equation G = Vy,\n which denotes the absolute weight of the body, F its volume, and y its fpecific gravity. For a sphere V—^ d', and as the specific gravity ol KLEKITJ'S APPAKATUS. 35 silver is 10.474 we would have G = 5.483 d*, or if the diameter of the sphere was one millim., its weight should be 5.482 milligr. Accord- ing to Kleritj this equation would very rarely give the true weight of a silver button, and he has determined by experiments that for J y we must substitute y. = 6.133. The true weight of the button will then be found from the equation G = 6.123 ^ = f<. <:?'. The same table may be used for Bueger's instrument, after determin- ing by measurement the diameter of the silver button in millimetres. Klerifj's apparatus is made by the mechanician Lingke, in Freiberg. — [Transl.] Taile showing the percentage of silver from one assay-centner of ore, etc. i Weight or Dia in Weight or Dia in Weight or Dia in Weight or Millim. Percentage MUlim. • Percentage Miliim. Percentage Miliim Percentage = judK = Mii: = /iid». = /ia: O'OI o- 000006 0-26 0-107618 o.5i 0-812222 0.76 a. 687860 0.03 0.000049 0-27 o-i2o5i9 X).52 0-860943 0.77 2.79535a o.o3 o.oooi65 '0-28 o.i344i2 0.53 0-911574 0.78 2-905682 o.o4 0.000392 0-29 0-149334 0-54 0-964152 0.79 3-018878 c.o5 0.000765 o-3o o-i6532i 0-55 I -018714 0.80 3-134976 c o6 Q.ooiSaS o-3i 0-18241,0 0-56 I -075297 0.81 3 -25401 3 0.07 0.002I00 0-32 0- 200638 0.57 I -133937 0-82 3-376026 O'OS O.oo3i35 0-33 0-220042 0.58 I -194671 0-83 3-5oio52 0.09 0.004464 0.34 -240658 0.59 1-257536 o,84 3-629126 o.io Q. 0061 23 .0.35 0-262524 0-60 1-322568 O.S5 3-760287 O-II O.oo8i5o 0-36 0-285675 o-6t 1-389805 0-86 3-894571 0.12 o.oio58i 0-37 o-3ioi48 0-62 I -459282 0-87 4-o32oi4 o.i3 o.oi345i 0-38 0-335981 0-63 I -531038 0-88 4-172653 o.i4 0.016802 0-39 0-363210 0-64 i-6o5io8 0-89 4-3i6525 o.i5 o. 020665 o-4o 0-391872 0-65 1.681529 0-90 4-463667 0.16 -025080 o-4i 0.422003 0-66 1.760333 0.91 4-6i4ii5 0.17 -030082 0-42 0.453541 0.67 1.841572 0-92 4.767907 o-iS 0.035709 0-43 0-486821 0-68 1-935267 0-93 4.925078 0.19 0-041998 0-44 o.52i58i 0-69 2.01 i46o 0.94 5-085666 0.20 0.048984 0-45 0-557958 0-70 2.100189 0.95 5-249707 0.2I 0.056705 0-46. 0-595988 0.71 2-191489 2-285398 2.381951 0.96 5-417239 0-22 0-065198 0-47 0-635708 0-72 0.97 5.588297 0.23 0.074498 0-48 0-677155 0-73 0.98 5.762919 0-24 0.084644 0-49 - 72o365 0.74 a. 481186 0.99 5-941141 0.25 0-095672 o-5o 0-765375 0-75 2.583i4i 1 .00 6-i23ooo 4. A good Magnifying- Glass. — This indispensable instrument ia ■chiefly used to judge more certainly the results of experiments on reactions, and to measure the silver and gold buttons obtained by quantitative as- ..^^^^.JiSSfeii.— m™^ eays. A glass well suited for this purpose is composed of two lenses 36 flattnek's blowpipe analysis. of equal magnifying power, but so mounted that each glass can be used alone, or one brought over the other, so as to use them together. Fig. 36 represents such a double glass. 5. Forceps and Pliers. — Various forceps are required for blowpipe assays, viz., a. Forceps witJi platinum tips, for holding an assay directly in the blowpipe flame, when testing its fasibility and other reactions. The forceps, which should be about one g- , »';' , 'iiVVi'ri"T i I hundred and thirty millim. long, are shown in Mg. 37. b. Cutting Fliers, or Nippers, Fig. 38, such as Berzelius employed for breaking off small assay pieces from the minerals to be exam- ined, without injuring the speci- mens. They resemble nail nip- pers, except that the cutting edge is broad and stout, rather than Fig. 88. ^—^^— sharp. c. Steel Pliers, Fig. 39, necessary in separating the slag from the raw lead obtained in gold and silver assays, and for other operations. The jaws of these forceps must be some- what broad, and the inner surfaces should not be cut like a file, but should only be rough. d. Brass Forceps, Fig. 40, used for holding small objects, especially in qualitative assays. e. A similar pair of forceps, also of brass, but somewhat smaller, and having more pointed ends ; they serve for handling the weights, and also the gold -J and silver buttons, when measuring them upon the scale. /. Iron Forceps, Fig. 41, about one hundred and ten millim. long, which are used in clean- ing the lamp-wick and raising or lowering it in the socket. Kg. 39. a Fig. 40. Fig. 41. HS'STRUMENTS, ETC., USED IN BLOWPIPE ANALYSES. 37 6. A Hammer, of good hard steel, rectangular in section, with a polished flat face at one end and a broad edge at the other, as in Fig. 43. ^. An Aiivil, of hard polished steel, Fig. 48, is used for coarsely breaking minerals and products which are to be pulverized, and also to flatten reduced metallic buttons, to remove the slag from the lead in gold and silver assays, etc. The best J form -is a parallelopipedon, about fifty-five ^-- ^^^s^ \ millim. long, thirty-two millim. wide, and thirteen millim. thick. When breaking up hard and brittle substances or flattening small metal buttons, these may be pre- ^'^- ^■ vented from flying oflf by using an iron ring, of about twenty millim. interior diameter, and ten millim. high, which is pressed against the anvil with the fingers, while the substance surrounded by the ring is struck with the hammer. 8. A Steel Mortar. — Abich's mortar, Fig. 44, is best adapted for breaking up and pulverizing refractory metallic minerals, products, and various substances which have been melted on coal before the blowpipe. In the circular plate of hard steel, A B, \s a, cylindrical cavity, O, six millim. deep, into which the hollow iron cylinder, D E, twenty-one millim. high, with an exterior diameter of twenty-four millim., exactly fits, and into this again fits a stout solid cylinder of hard steel, 'F, forty-five millim. high and eight- een millim. in diameter, which is rounded at its upper end. Both cylinders are turned so as to fit each other exactly. The substance to be pulverized is placed within the cylinder, B E, the pestle, F, set in upon it and struck a few times with the hammer, while both cylinders are pressed against the steel plate with the fingers. Upon removing the two cylinders, one after another, the substance will be found reduced to a rather fine powder which may be rubbed still finer in the agate mortar. 9. An Agate Mortar, Fig. 45. — By pulverizing very hard bodies in such a mortar it receives, in time, fine scratches, into which some metal is liable to be rubbed, when powdering and washing metalliferous slags, and it must then be cleaned each time ivith moistened bone-ash. 10. A few Files, triangular, flat, half-round, and round, varying in size and fineness, are used for different purposes. A rasp is also 38 PLATTU-EE'S blowpipe AlfALTSIS. of excellent serrice in shaping coals and cleaning them ' aftei use. 11. A Knife and a small pair of Scissors, with strong cutting edgea 12. A Steel Magnet,^ in the shape of a square bar about eighty-five miUim. long and four miHim. square, wedge-shaped at one end. 13. Coal borers. — In quantitatiye assays holes must be bored in the coal, for which yarious borers are required. Three different ones are used, yiz., a. A borer, Fig. 46, to bore holes in the coal for the fusion of silver, gold, copper, and other assays. It is square, and the sides are filed so that it looks like a double chisel, the _j_ edges crossing each other at a right angle and being very slightly convex. ^'s «• The breadth of each chisel is eight millim. and the borer is provided with a wooden handle. The borer is placed at a right angle against a cross-section of the coal and turned rapidly on its axis, with a moderate pressure, alternately toward the right and left, until the required depth is reached. After removing the borer the dust is blown out of the hole, the width of which depends on the size of the borer, while its depth is regulated by the height of the paper cylinder in which the assay to be fused is packed. Thus, in case of an assay charged for copper, the hole is shallower than with the charge for an assay of silver ore rich in copper, because the latter contains much test lead. b. A conical borer, for boring larger holes, the longitudinal section of which is a semi-ellipse. Its upper diameter is twenty-two milHm. and its length eighteen miUim. The further arrangement of it is shown in Fig. 47. The instrument is used just as the preceding borer, but as soon as the side, a, reaches the level of the perforated side of the coal the boring is stopped and the coal dust cleared from the hole. c. A long coal borer. Fig. 48. One end consists of a double chisel six millim. broad, made like the first borer for cylindrical holes. It ^__ ^ is used in boring through the ( ^~__ ^^^.^ai 1^ front side of the coals fastened in the coal-holder to be described ! *^- ^- below, and for boring through the coal covers which are required when fusing quantitative lead, bis- muth, tin, nickel, and cobalt assays in clay crucibles. The othei INSTRUMENTS, ETC., USED IN BLOWPIPE ANALYSES. 39 end, which is nine millim. wide, is shaped like a spatula, with a sharp edge, and is used for boring holes in coal for qualitative analysis, when they are to be rather deep. 14. Cupel Moulds, with the stamps and stand. — For cupelling the argentiferous and auriferous lead obtained from silver and gold assays small cupels of bone-ash are required, which are conveniently made by striking them in a metallic mould and using them for cupellation, without removing them from the mould. Two such moulds may be had, one for larger, and one for smaller moulds, Fig. 49, A B, but this is not indispensable, as the larger one is suflBcient under all circum- stances. [It is, indeed, better to have two of the larger size only, as then, when the refining cupellation has been performed on the cupel, it can still be used for the scorification of the raw lead, thus effecting a saving of time and material. Transl.] and D are the stamps. The moulds are of iron and are seventeen millim. in diameter, the cavity being worked rough, so that the cupel ^^B ^'s struck in it may not fall out, as would be very likely to happen if the cavity were smooth. The stamps are of hardened steel, and like the hollows in the moulds their shaping faces are segments of spheres, but of a somewhat larger diameter, and polished. That the mould may be more securely held when hot, a cross is filed on the under side, so that one point of the forceps may be put into one of the four openings, while the other point is pushed over the upper part of the mould, which can thus be transferred to any desired place. The cupels are made by pressing the mould full of bone-ash, set- ting the proper stamp vertically upon it, and compress- ing the bone-ash with a few strokes of the hammer, until the convex face of the stamp touches the inner edge of the mould on all sides, whereupon the cupel is finished. A stand, about ninety millim. high, Fig. 50, supports the cupel during the cupellation. It is bored out down to c, and a stout iron wire is inserted in it, so as to stand quite free from the wood down to that point. The cupel mould is then placed on the cross above, so that the cross cuts in the mould do not coin- cide with the cross pieces, but come between the arms, in order that the hot mould may be removed with the forceps when the cupellation is done. [It is frequently desirable in qualitative examinations, 40 PLATIXEE S BLOWPIPE AKALYSlb. to cupel substances with lead, and then, if the operator does noi possess the quantitative apparatus, a cupel may be readily made by boring a hole about a quarter of an inch in width and depth, in a piece of charcoal, and filling it with a stiff paste of bone-ash. This is pressed down and made slightly concave, with the pestle of the agate mortar, and then thoroughly and slowly dried, B. B., or over the spirit-lamp. — TransL] 15. A Mixing Capsule of sheet-brass or horn, polished on the inside and shaped like Fig. 51. It is fifty-eight milHm. long, twenty-two miUim. wide in the widest part, ^^ and five millim. deep, and at the lip, where it ^" ^' begins to round off, seven miUim. wide and three millim. deep. It is used, especially in quantitative assays, to pour the mixed charge conveniently into the soda-paper cylinder. 16. .4 Spatula of polished iron, of the shape shown in Fig. 52, and -- ^- — "-^ j ninety-five millim. long. It ii «=^=====^=— used for mixing charges, but more ^- 62. particularly in roasting ores to be quantitatively assayed for metals, and for various other purposes. 17. Coal-holder with platinum wire and shield. — In making quan- titative assays which must be roasted, or fused in clay crucibles, and require a strong heat, the coal used must be protected, at the end employed by an envelope of sheet- iron, the coal-holder. Fig. 53 shows two sides of this holder, as pro- posed by Plattner. Each of the four sides is thirty-two millim. wide and thirty-six millim. high. On the front side,. B, is a slit, h, ending I in a round opening, a, seven millim. in diameter, and on the rear side is LB '^~" an iron screw, c, on the inner end I of which is a plate, d, that turns '^' ■ on its axis, while to the outer end the wooden handle, e, is attached. The screw, c, is below the middle of the coal-holder, so that when the coal is burned out the pressure may not cease, nor the coal fall from the holder. The nut,/, outside of the coal-holder, in which the iron screw works, is arranged to slide ' in and out. There is a small piece of sheet-iron, Ji, fastened on the front of the coal-holder by a small rivet, so that it can be turned to close the slit, J, or leave it open, as the dotted lines show. In one pide, A, of the holder there is also a small slit, i, eight millim. long INSTRUMENTS, ETC., USED IN BLOWPIPE ANALYSES. 41 Fig. 64. and 0.8 millim. wide, for the insertion of the platinum wire, to be described directly, and below the slit is a small brass socket, Tc, in which the end of this wire is inserted. When an ore is to be roasted in a clay capsule, or an assay fused in a clay crucible, the capsule or crucible must be so placed as to stand free in the ca^ty and not touch the coal. This is accomplished by means of a platinum wire eighty- three millim. long, and 0.6 to 0.7 millim. thick, which is bent with the pliers into the shape shown in the natural size in Fig. 54. The ring, A, is first formed, then, at I, the straight part is bent back somewhat, and up- ward at an obtuse angle, corresponding to the inclination of the sides of the cavity in the coal, and lastly, the re- maining part is bent downward at a right angle, as is seen at B. The length of the upper horizontal portion must, before bending the wire, be measured off, equal to- the distance from the opening in the socket, h, to the side of the cavity in the coal {vide Pig. 19, F), as may be seen at n. Pig. 55, which represents the coal-holder with the coal and the inserted wire. The coal prism is introduced into the coal-holder from below, so that the upper side, on which the part 5 of the wire rests, may reach exactly to the slit, i. On the wire, opposite the opening, a, is hung a small shield of thin platinum foil, Pig. 54, Q (natural size), which is used owZyiwroas^tw^ and serves to prevent the coal from burning out too soon at the part most exposed to the pointed flame. 18. A small ivory spoon, eight millim. wide on the exterior and shaped like Pig. 56, quite smooth and pol- ished ; also a small brush for cleaning the scale-pans, mixing capsules, and roasting capsules from any adherent fine dust. 19. A test lead sieve. — The test lead for blowpipe assays must be as fine as possible, so as to mix better, and the granulated lead must therefore be sifted through a small sieve, the bottom of Fig. 66. Iljfp^ h llilnfP— ■:-"-:-:¥SS:s= ijr^ll , TBimrnT- ^'S- B7. 42 PLATTNEB'S BLOWPIVB ANALYSIS. J which is pierced with holes through which a moderately coarse needle will pass. This sieve is made just wide enough to hold the box of the clay capsule mould before described, and does not, therefore, require a special place when transported. 20. A test lead measure. — It is troublesome to weigh out the test- lead required for a quantitatire gold or silver assay, and since it makes no great difference if a trifle too much or too little is used, Harkort employed a measure similar to that used for gunpowder. It consists of a glass tube, Fig. 58, thirty-five millim. long and seven to eight millim. wide, ground smooth at both ends, into which a wooden cylinder exactly fits. On the cylinder are several divisions which have been before determined by weigh- ing out five, ten, fifteen, and twenty blowpipe centners of fine test lead and pouring it into the tube. To charge an assay with ten ctrs. of lead the wooden cylinder is drawn out until the line marked 10 is just even with the bottom of the tube, when the empty space above will hold just ten ctrs. of test lead, supposing that the lead used is of the same degree of fineness as that used in determining the divisions. Fig. 68. 31. A small solid cylinder of wood, which is used for pre- paring the soda-paper cylinders, p. 25. It is twenty-five millim. long and seven millim. thick, as shown in Mg. 5.9, B. To prepare the paper cylinders the wooden cylinder is laid on the paper, Fig. 59, A, and the latter rolled around it. The projecting end of the paper is then pressed down on the wood in several places with the little ivory spoon, and finally the closed end is pressed against the table so as to shut it tighter. 22. Several cylindrical boxes of hard wood, Fig. 60, for dry reagents, and several glass bottles with well- ground stoppers, Fig. 61. The bottles and boxes are ^set in a wooden stand or box, in rows behind one another. Somewhat larger bottles are kept in a separate stand for liquid re- agents which are more frequently used, as nitric acid, hydrochloric acid, etc. 23. For more extended blowpipe exami- nations which often necessitate the employ- ment of the wet process, various pieces of apparatus and utensils are required, which wiU be here mentioned together. Glazed porcelain vessels, Figs. 62, 63, 64. Those Fig. 59. IJS'STRUMEKTS, ETC., USED IN BLOWPIPE ANALYSES. 43 like Fig. 63 are most suitably made of two sizes : the larger ones about thirty millim. high and forty-five millim. wide in the middle and the smaller ones twenty-fiye millim. high and thirty millim. wide. A few watch-glasses of corre- sponding diameter serve to cover these vessels. Different sizes of Fig. 63 are likewise to be recom- mended, and paint or indian-ink saucers can be used for the purpose. The smallest size, Fig. 64, twenty-five millim. wide and ten millim. deep, is used to heat, over the spirit-lamp, substances which attack platinum. For dissolving com- pounds in acids, test tubes. Fig. 65, ar-e used, which are kept in a folding frame^ of wood or tin. Several small beakers may be advantageously used for similar purposes, as well as for filtrations. A few small glass funnels, which can be placed on the test tubes, are indispensable; for larger fun- nels a small filter stand. Fig. 66, is useful. [It may be very con- veniently replaced by a ring attached to an arm, which fits in the arm of the evaporating ring, D, Fig. 1, or it may be separately fitted to the lamp stand. — TransL] The filter-paper used must leave but a small amount of white ash, since the ignition of a part of the filter is some- times unavoidable when trifling precipitates are to be further examined. A small glass pipette, Fig. 67, about one hundred and fifty millim. long and blown out in the middle into a bulb, twenty-five L '"■ ^^' millim. wide, is also useful. When this is lacking, a tube, ten millim. wide, drawn out to a point at one end, can be used. Finally, a small wash bottle, Fig. 68, or a dropfing glass, Fig. 69, is necessary. By blowing air into the tube, a, Fig. 68, which opens close under the cork, a steady stream of water is forced out through h. A glass flask of about forty-five millim. diameter is quite large enough. On inclining the spout of the half-filled dropping glass, Fig. 69, so far that the water runs into it, a few drops will fomo 44 PLAITlfEE'S BLOWPIPE ANALYSIS. thiiv way out separately, which is of advantage when anything is to be moistened with a drop of water. It is only necessary to direct the spout downward and blow through the glass tube to force the water out in a very fine stream. 34. A charcoal saw, about one hundred and fifty millim. long, eighteen millim. wide, and one millim- thick, with a wooden handle. A bow saw may be used with more advan- tage in sawing large pieces of coal, but in travelling, when such large tools cannot be car- ried, and a stock of suitably cut or artificial coals is gener- ^- "s- ^ig- ^- ally on hand, the first saw will answer the purpose. 25. Various tin vessels, in case the apparatus is carried during a trip, when it is necessary to take a stock of oil, alcohol, coals, and clay vessels. Tin flasks, covered with dark lacquer, serve for oil and alco- hol, the openings being closed like those of the blowpipe lamp. Four- sided cases hold the various coals, which must be tightly laid in, as the artificial coals are easily injured by Motion or shocks. A similai case is needed for the safe keeping of the glass tubes, mat- rasses, test tubes, and funnels. Plattner has recommended a particular case for keeping the clay capsules and crucibles. It consists of a hollow brass cylinder, into which a frame of the same material can be inserted, capable of holding twenty-five clay crucibles, and ten capsules. Pig. 70 shows the arrangement of such a case. When the frame is full of crucibles or capsules, the extra space is packed with soft paper or wool, and the cylinder put over it. In order that the cylinder may not slide back, small eyes are attached at a and b, which can be fastened together by a One thread. The ring into which the four upright wires are set has a slit at c, which is so wide that the points of the forceps can pass through conveniently when a crucible or capsule is lifted out of the frame. [26. A lutton brush, for cleaning gold and silver buttons; a brush of stiff bristles, bound firmly by a wide metal band.] Finally, it is necessary so to pack the objects enumerated, that when Hi l! ill Fig. TO. REAGENTS USED IN BLOWPIPE ANALYSES. 45 they are to be taken on a journey the separate ones may be easily found, while the whole apparatus has a compact appearance. A wooden box that can be locked is suitable for this. In the lower part a special arrangement must be made, so that all the larger objects, which cannot first be put in a particular case, may be securely packed away. Above these objects come the others, which are partly in small separate cases, and partly laid side by side in wooden trays, lined with soft leather, and haying cavities corresponding with the separate objects. The cover of the box should also be lined with an elastic cushion covered with soft leather. The wooden boxes and the glass bottles, Figs. 60, 61,. and two glass bottles of cobalt and platinum solution, all of which stand by themselves in a rack or small box, can also be packed in the same box. If other liquid reagents are to be carried, it is best to ketfp them in a small separate box, as some of them give off vapors which are injurious to metallic objects. VT. Reagents used in Qualitative and Quantita- tive Blowpipe Analyses. In blowpipe analyses, as in all chemical examinations, it is essen- tial that the necessary reagents should be used in the purest possible condition, and they will, therefore, be not only enumerated here, but in cases of particular importance, the necessary remarks on their purification, the signs of their purity, and the object of their employ- ment will be made, A. Reagents for blowpipe analyses made without the aid of the wet process. a. General reagents. 1. Carbonate of soda.*— Roi\i the carbonate and bicarbonate may be used if chemically pure, and free from sulphuric acid in particular. Preparation. — Commercial bicarbonate of soda is pulverized, put into a glass funnel loosely stopped with cotton and the surface, after being made even, is covered with a circle of double filter-paper, so that the edges, which are bent ifpward, lie tight against the funnel. It is then washed by pouring on a small quantity of distilled water at a time, until the filtrate, acidulated with nitric acid, is not clouded either with nitrate of silver or chloride of barium. It is then very %oroughly dried, pulverized, and kept in a wooden box; or it may » Hereafter the simple word soda wBl be used in place of carbonate of soda in thii book. 46 plattner's blowpipe analysis. be converted into the simple carbonate by igniting it gently in a shallow porcelain dish, or a porcelain crucible, over a spirit-lamp with a double draught. It must then, however, be kept in a glass- stoppered bottle. Tests and itse. — ^A small quantity of the purified salt is treated with the R. F. on char- coal, until it has sunk into the coal. When cold, the spot is cut out, and the mass laid on bright silver foil and moistened with enough water to wet the foil also. If free from sulphuric acid, the surface of the silver remains unaltered, but if a trace is present in the salt it is reduced with the soda to sulphide of sodium, by the treatment on coal, and causes the silver to become yellow, brown, or black from the sulphide of silver formed, either very soon, or after a few minutes. Soda serves as a test for sulphuric acid, and also, in qualitative and quantitative ' analyses, to decompose compounds of silicic, tungstic, and titanic acids, and to promote the reduction of various metallic oxides. 2. Neutral oxalate of potassa. — Binoxalate of potassa is dissolved in water, neutralized with potassa, filtered, and evaporated to dryness, being stirred with a glass rod toward the end of the operation, while a suflBciently high temperature is employed, but not enough to de- compose the salt. The dry mass is pulverized and kept for use in a well-closed bottle. Tests and use.— The solution of the neutral salt must remain unclouded on adding sulphide of ammonium. When completely dry, this salt, at a low red heat, evolves carbonic oxide, without carbonic acid, and is, therefore, admirably suited to the exam- ination for arsenic, and is better than soda for reduction assays on coal. 3. Cyanide of potassium. — It can be bought suflBciently pure. Use. — The salt prepared by Liebig's method eoDtaiiis cyauate of potash, which does no harm. It Is chiefly used as a reducing agent, being in this respect always preferable to soda, and in many oases to oxalate of potash. 4. Borax (biborat« of soda). — Commercial refined borax is per- fectly suited to blowpipe assays. The pulverized hydrated salt serves for qualitative analyses, but for quantitative assays, where all intu- mescence must be avoided as far as possible, it is better to employ the borax in the state of glass. It is fused in a platinum crucible over a ipirit-lamp with a double draught, or on coal before the blowpipe, in the 0. F., and the glass broken to coarse powder between paper, or in the steel mortar, is rubbed somewhat finer in the agate mortar and kept in a glass-stoppered bottle. Impure borax can be purified by recrystallization and washing the crystals in a glass funnel with a little cold distilled water, after which they are dried and pulverized EEAGBNXS USED IN BLOWPItil ANALYSES. AT 'J-ests and use.— A. small quantity of pure borax melted in the loop of a platinum wire must not give a colored bead in the O. F. or the R. F., and dissolved in water i( should give no precipitate with carbonate of soda, and after adding nitric acid to its solution there must be no precipitate with nitrate of baryta or nitrate of silver. Boracic acid has the property of combining with oxides at a high temperature, driv- ing out weak acids, and with the aid of the 0. F. disposing metals, and sulphur, and haloid compounds to oxidize. Borates of the oxides result, which fuse readily with borate of soda and give a clear glass. The borax contains, besides borate of soda, free boracic acid, and is therefore inclined to dissolve bases and acids, and to form basic as well as acid double salts, which are all to a certain degree fluid. These salts generally remain clear on cooling, and thus the color produced by the combination with the dis- ' solved body is the more clearly brought out in quab'tative examinations. In quantita- tive assays it serves, partly alone and partly in common with soda, to dissolve the earths and metallic oxides of difficult reduction occurring in the ores and minerals, as well as to separate various metallic arsenides from one another. 5. Salt of phosphorus or microcosmic salt.* (Phosphate of soda and ammonia.) — According to Berzelius this salt, which is not always obtained free from chloride of sodium, is best made as fol- lows : One hundred parts of crystallized phosphate of soda and six- teen parts of chloride of ammonium are dissolved, with the aid of heat, in thirty-two parts of water, and the boiling-hot solution filtered and allowed to cool. The double salt crystallizes while cool- ing, leaving in the solution chloride of sodium and some of the double salt, which, however, cannot be crystallized out free from chloride of sodium by further evaporating the mother liquor, and cannot, therefore, be used for blowpipe examinations. After com- pletely decanting the mother liquor the crystals are dried between filter-paper and the salt kept for use in wooden boxes. When heated on coal or platinum wire it boils, swells a little, and gives up its water and ammonia, leaving behind acid phosphate of soda, which melts quietly and solidifies on cooling to a clear colorless glass. Tests and me. — ^If the salt is not free from chloride of sodium it sometimes gives a glass which is not clear on cooling, and when a little oxide of copper is dissolved in the salt which is fused on platinum wire, the outer flame is colored blue. In this case it must be redissolved in a little boiling water and set aside to recrystallize. When freed from its water and ammonia by fiision, the salt acts particularly through its free phos- phoric acid, which exerts a powerful solvent action on many substances under examin- ation. Taking up all bases it forms with them more or less fusible double salts, the transparency and color of which are chiefly to be regarded. It serves also to separate the bases in the test for fluorine. While this salt is analogous in its action to biborate of soda, the glasses which it forms with metallic oxides generally differ in color and intensity from those obtained vrith borax and the same oxides by similar treatment. • For this salt the 'etters S. Ph. will be used. iS PLATTNEE'S BLOWPIPE ANALYSIS. 6. Nitre {nitrate of potassa). — Commercial saltpetre is dissolved in a small quantity of boiling water, and the boiling-hot solution fil- tered and set aside to crystallize. After a small quantity of crystals has formed, the mother liquor is poured off and the crystals dried between filter-paper and kept in wooden boxes. Nitre serves only as an oxidizing agent. 7. Bisulphate of potassa. — This salt can be i)repared thus: One part by weight of pure sulphuric acid is poured over two parts of coarsely-broken crystals of pure sulphate of potassa in a porcelain crucible, which is then gradually heated over a spirit-lamp until the whole forms a fluid clear as water, when the crucible is removed and the fluid salt allowed to cool. It solidifies very quickly, appears quite white, and can be obtained in one piece by turning the crucible over when cold. The pulverized salt is preserved for use in a glass-stop- pered bottle. Use. — It is nsed In testing for lithium, boracic acid, nitric acid, flaorine, bromine, chlorine, and iodine, and for decomposing compounds of titanic, tantalic, and tungstle acids. It can also be nsed to separate baryta and strontia from the other earths, and various metallic oxides by the wet way, when the blowpipe alone is not sufHcient. The method of using it will be especially described under the separate assays. 8. Vitrified ioracic acid. — This can be obtained from the chemical works of as good quality as it can be prepared, and more cheaply. It is kept in the form of powder, or in small fragments, in a tightly- closed bottle. It serves eBpeolally in qualitative examination to detect a small quantity of copper in presence of much lead. In quantitative assays it is quite indispensabla in separating lead from copper, aud from alloys of the noble metals, which fuse with difficulty and cannot be quite freed from it on the cupel. 9. Nitrate of cobalt in solution. — Pure protoxide of cobalt is dis- solved in the necessary quantity of dilute nitric acid, the solution evaporated to dryness at a gentle heat, the dry salt dissolved in water, and the filtered solution kept in a bottle. The solution should not be concentrated, as this would not answer the purpose in all cases. The protoxide of cobalt must be chemically pure, containing neither protoxide of nickel nor sesquioxide of iron, and there must be no potassa adhering to it. The latter can be removed by boiling the protoxide with distilled water. Use. — The nitrate of cobalt serves for recognizing various earths and metallic oxidet with which protoxide of cobalt forms, on being heated to redness in the O. F., com- pounds distinguishable by their peculiar colors. As only one or two drops are required for an assay it is convenient to take oat th* requisite amount with a small instrument, and thns moisten the substance to be ex BEAQEJfTS USED IN BLOWPIPE ANALYSES. i\} aniined. This is most simply effected with a platinum wire, spoon-shaped at one end, and fixed in a cork, or with a thin glass tube, likewise fastened in a cork which fits the neck of the bottle, Fig. 71. The latter is very convenient, since the tube acts like a pipette when it is dipped into the solution and the cork pressed a little into the neck of the bottle, the compres- sion of the air forcing some of the solution into the tube. On draw- ing out the cork and the filled tube, and closing the wide end of the latter with the finger, one, two, or several drops may be allowed to escape without touching the substance with the narrow end of the tube. On a journey the bottle can be closed with a glass-stopper, and the pipette kept by itself. Fig. 71. ., 10. Test lead, finely granulated, and also in lumps, as free as possi- ble from other metals, particularly gold and silver.— When the gran- ulated test lead can be obtained from lead and silrer works it need only be sifted through the small sieve, Pig. 57, and the part which passes thi'ough is kept in a wooden box. If such lead cannot be had the requisite amount may be prepared by reducing the lead from ace- tate or sugar of lead with zinc, in the following way: Dissolve sugar of lead in a small quantity of boiling water, then place a zinc rod in the filtered solution, and after about six hours, carefully detach the metallic lead from the rod, so as to expose a fresh surface, repeating the operation every six hours, until all the lead is separated in the .metallic state. The lead is then purified from the adherent acid solution, which contains zinc, by repeated washing, and dried be- tween filter-paper in a warm place, after which it is rubbed in a porcelain mortar and the fine part separated from the coherent mass with the lead sieve. Test lead is chiefly used in quantitative gold, silver, and copper assays. The volume of a weighed amount of test lead prepared from sugar of lead is to the volume of an equal weight of granulated and sifted lead as six to five, and where the former lead is to be used by measurement for silver and gold assays with the measure. Fig. 58, and not by weight, there must be added one ctr. for every five ctrs. in order to obtain the proper weight. When the granulated lead cannot be easily obtained the preceding method with sugar of lead aflFords the readiest means of preparing pure and finely divided test lead. 11. Tin.— Oidinary tinfoil is used, cut into long strips twelve millim. wide and rolled up tight. Tin serves to produce the lowest degree of oxidation in glass fluxes, paiticularly in case of trifling quantities of such metallic oxides as can be reduced to protoxide or sub- oxide, and in this state give more conclusive results. A little of the tin is cut off, laid directly against the glass bead and quickly fused, for a moment only, in the E. F. After adding the tin the blast must not be kept up too long, partly because the tin will entirely reduce many metals which should only be brought to the lowest state of oxi- dation, and thus recognized by the color of the glass, and partly because so much tin 4 ■'>0 plattner's blowpipe an^altsis. may be dissolved, espeoially with S. Ph. that the glass becomes quite opaque. Hirschwald uses solid stannous chloride in place of tin. 13. Iron, wire as thick as a moderately coarse knitting-needle. It serves In the qualitative test for antimony and in the quantitative lead and bismuth assay. 13. Silver. A small piece of sheet silver is used in reactions for sniphide of sodinm or soluble sulphides It is also required in many quantitative gold assays and can be best reduced from chloride of silver, being hammered and rolled into a thin sheet from which the desired amount may be easily cut. 14. Gold, in small buttons, up to eighty milligr. in weight, or as foil. — It may be had pure by dissolving gold coin in nitro-muriatic acid, diluting the solution properly with water and letting it stand until it is clear and the small amount of chloride of silver has set- tled, when it is filtered, and the gold precipitated with sulphate of iron. After the finely-divided gold has settled, it is collected on a filter, well washed, dried, and gently ignited. It is best to ignite the filter separately. From this gold, buttons of any desired size can be made by fusion on coal with a little borax. Gold serves in many reduction assays to collect small quantities of reduced metals, which are to be simply separated, or recognized, or else, as is frequently the case, are to be quantitatively determined, viz., copper and nickel. 15. Arsenic in the metallic state. — If it cannot be purchased, powdered mispickel is treated ia a glass retort provided with a receiver, as long as a sublimate of metallic arsenic collects on the neck of the retort. When cold, the retort is broken and the arsenic which has collected toward the end and is free from sulphur is kept for use. It serves in the nickel and cobalt assays to convert the metallic oxides into arsenides. b. Special reagents used only in certain examinations. 1. Test papers of blue and red litmus and BrazU-wood paper cut into small strips. — The paper is colored in the following way : a. Blue litmus paper. — One part of litmus, of the best quality, is rubbed to a coarse powder and mixed with water to a paste, which is tied up in a bag of fine linen and hung in a vessel containing ten times as much boiling water as the weight of the litmus employed. The coloring matter is extracted, forming a solution which is poured into a porcelain dish, and the strips of paper, after being drawn through it with a glass rod, are hung upon a cord to dry, in a shaded KEAGENTS USED IN BLOWPIPE ANALYSES. 51 place free from dust. Fine filter-paper in strips two inches wide ia best suited for this purpose. I. Red litmus paper. — A litmus solution prepared as above is red- dened with the least possible amount of dilute sulphuric acid, added very gradually while the liquid is strongly stirred, so that no more acid is added than is exactly necessary, as otherwise the paper is not sensitive enough. The paper is then prepared as before. c. Brazil-wood paper. — Shavings of Brazil-wood are boiled in a glass flask with water, the liquid decanted from the shavings and paper colored with it in the same way as with the litmus extract. Use. — Blue litmus paper is used for recognizing free acids ; red litmns paper is a sensitive reagent for free alkalies. Brazil-wood paper is used especially in the test for fluohydric acid, which imparts to it a yellow color. 3. Antimonate of potassa, in a pulverized state. — One part of antimony is mixed with six parts of nitre and deflagrated in a red- hot clay crucible. The resulting mass is pulverized, lixiviated with cold water, and then treated with water at a boiling heat, which dis- solves the neutral antimonate of potassa, and an acid salt remains. The solution of the neutral salt is separated from the residue by filtration, evaporated to dryness, and the dry salt heated strongly, antil it is quite free from water and has assumed a white color. It is pulverized while warm and preserved in a well-closed bottle. It is employed to detect small quantities of carbon in compound bodies. When ignited with them it yields oxygen to the carbon, forming carbonate of potassa, which gives up its carbonic acid in the form of gas when dissolved in water, and decomposed by nitric acid while still quite warm. 3. Common salt, or rock salt {chloride of sodium) ; decrepitated, or fused and powdered. Its use is very limited, but it is employed with advantage as a cover for the neces- sary charges in quantitatiye lead, bismuth, tin, nickel, and cobalt assays, when they are fused in clay crucibles. 4. Fluor spar, heated to redness and kept in a wooden box. — It must be quite free from boracic acid, which, according to Kersten, is not always the case. When mixed, therefore, with bisulphate of potassa and fused on platinum wire, in the blue flame, it must not color the outer flame green. It serves, in connection with bisulpliate of potassa, to detect lithium and boracie ■cid in compounds. 5. Quartz {silicic acid). — Pure silicic acid, separated from the sil- icates in the course of chemical analysis, may be used, provided it has a perfectly white color after ignition. Kock crystal may also be 52 plattnee's blowpipe amtaltsis. used, being coarsely powdered between paper and then pulverized in an agate mortar. Fnsed to a glass with soda it serves to test substances for solphnric acid, and, in combination iritti soda and twrax, to separate tin bom copper ; also irequentlj, in con- nection with soda, to test for phosphoric acid. 6. Oxide of copper. — It is most simply prepared by dissolving ptue copper in nitric acid, evaporating to dryness, and gradually heating the dry mass to a strong red heat in a thin porcelain dish. It serves chiefly to detect small quantities of chlorine in compounds. 7. Gypsum, free from potassa and soda. Mixed with fluor spar it serves to detect lithia and boraolo acid, and serves to detect alkalies in silicates. 8. Chloride of silver, in dry powder or fused. It serves to produce certain colored flames which appear more distinct with It^ than with hydroohlorie acid. 9. Starch meal. It acts as a reducing agent in various quantitative assays. 10. Graphite. — Commercial graphite is often very impure, usually containing many earthy particles, and cannot then be used for blow- pipe assays. A piece must be sought which is soft, but not scaly and lamellar, for such graphite bums with diflBculty. It is pulver- ized and its purity tested by burning a little of the powder in a clay capsule. When a pure piece cannot be obtained the impure graphite is purified in the following way : After being pulverized as fine as possible it is mixed with twice its volume of carbonate of potassa and heated to redness in a covered clay crucible. The heated mass is then powdered and boiled with water, and any admixture of quartz thus removed with the alkali; by heating the remaining graphite with dilute nitric acid the iron and earths can be dissolved and separated by filtration and thorough washing. The graphite which remains is thoroughly dried and kept for use. [The graphite ob- tained by scraping soft lead pencils of the finest quality answers every purpose. — Transl.] Fnre, veiy finely-divided graphite serves well as an addition in roasting gnhstancet- containing sulphur or arsenic in which the copper is to be quantitatively determined. 11. Magnesium, in slender wire, serves to detect phosphoric acid. 12. Potassium iodide and sulphur. — A mixture of equal volumes- of each, finely powdered, serves to detect bismuth. REAGEISTTS USED IK BLOWPIPE ANALYSES. 53 13. A touchstone for testing the precious metals and their alloys.— It consists of hard black basalt or flinty jasper ground smooth. The metallic streaks are removed by smearing the stone with a little oil and rubbing it with charcoal, after which the surface is wiped iff and appears clean and quite black again. B. Reagents for blowpipe analyses which are performed with the aid of the wet process. a. General Eeagents. 1. Sulphuric acid, concentrated. It serves to intensify the reactions of boracic and phosplioric acids in the outer flame, with substances containing those acids ; to decompose many compounds of fluorine, and in the examination for arsenic. It is used in a dilute state to detect lime, under certain circumstances, and also to separate baryta and strontia from other earths. 2. Nitric acid, chemically pure. It is used to peroxidize protoxide of iron in solutions, to separate silver from gold, and is of advantage in other cases. 3. Hydrochloric acid. It serves to detect small quantities of ammonia in salts ; the ammonia being set free by soda, under the influence of heat, and brought into contact with a glass rod moist- ened with the acid, when a white cloud is produced. It also serves to detect carbonic acid in compounds soluble in hydrochloric acid. Further, to dissolve various earthy salts, to decompose many silicates, the bases of which cannot be certainly determined by the blowpipe alone; also in the quantitative tin assay; and finally, to form various chlorides, for the sake of flame colorations. 4. Acetic acid. ■• Tests and use. — Acetate of baryta must not cause any cloudiness. It is only used in examining compound substances for chromic, vanadic, and phosphoric acids. 5. Oxalic acid. When dissolved it serves to precipitate lime from an ammoniacal liquid, and to separate zirconia, sesquioxide of iron, and sesquioxide of uranium from yttria and the oxides of cerium and lanthanum. It can also be used to reduce gold dissolved in aqua regia. 6. Caustic potassa, in solution. — It can be carried in the solid state during a trip and dissolved in the necessary amount of water when used. Dissolved in water it serves to separate alumina and gluoina from the sesqui- oxides of iron, manganese, and chromium, after they have all been precipitated from their solutions by ammonia and thoroughly washed. 7. Ammonia. Tests and use. — It must be free from ciubonio acid, so that a solution of chloride of calcium must produce no cloudiness, by the formation of carbonate of lime. It is 54 PLATTlfER'S BLOWPIPE ANALYSIS. used in blowpipe analyses, with the aid of the wet process, when the separate earths are to be detected in compounds, for the purpose of separating alumina, gluoina, yttria, and the sesquioxide of chromium. Iron, etc., from lime, magnesia, and prot- oxide of manganese in solutions, which In many cases must contain free hydro- chloric acid or chloride of ammonium. 8. Carbonate of ammonia. — It is kept in a powdered state in a glass-stoppered bottle. Dissolved in water it serves, in analyses which cannot be performed with certainty before the blowpipe alone, to separate glncina from alumina, and sesquioxide ol uranium from sesquioxide of iron, in the wet way. It is also added to the water used in washing precipitated phosphate of ammonia and magnesia, and is employed in roasting many quantitative assays, to secure the decomposition of certain metallic sulphates. 9. Platinic chloride. — This is prepared by warming very thin bits of platinum with twice their weight of hydrochloric acid and adding nitric acid by drops until all is dissolved. To remove the free acid the liquid is carefully evaporated to dryness, the browu res- idue dissolved in water, filtered, and kept in this state. It must not be too dilute. It is the best reagent in the wet way for potassa, when occurring in trifling quanti- ties in compounds with soda or lithia. 10. Distilled water. — When the aid of the wet way is required, distilled water must always be at hand. Evaporated on platinum foil it must leave no residue, and must not be rendered cloudy by salts of barium or silver. I. Special reagents of limited use. 1. Tartaric acid, in a crystallized state. — ^It is kept in a wooden box, and is used in the separation of iron from yttria and zirconia by sulphide of ammonium. 2. Oarbonate of potassa. — It is kept in the dry state in a glass- stoppered bottle. It replaces soda in the qualitatiTe test for tantalic and niobic adds, and may also be used in connection with soda for quantitative assays that mnst be fused in clay cruci- bles. 3. Neutral sulphate of potassa, in small crystalline crusts. — It is obtained quite pure from the apothecaries, and kept in a wooden box. It is ii-equently employed to detect zirconia and to separate the oxides of cerium, lanthanum, and didymium from other bodies by the wet way, when the blowpipe alone is not suiBcient. KEAQBNTS USED IN BLOWPIPE ANALYSIS. 55 4. Chloride of ammonium {sal ammoniac).— It is obtained quite pure from the apothecaries, but may be redissolved in hot water, filtered, and set aside to recrystallize. After decanting the mother liquor the crystals are dried between filter-paper and kept in a wooden box. It is used only in the assay for gold when pladnom or iridinin are to be separated. 5. MolyMate of ammonia. — ^It may be prepared by pulverizing molybdenite as finely as possible and roasting it in a small and quite shallow dish of platinum or sheet-iron, at a moderate heat, over, a gas-lamp, or spirit-lamp with a double draught, until the powder becomes yellow and is mostly conyerted into molybdic acid, which turns yellowish-white on cooling. It is then digested for some time with ammonia, which extracts the molybdic acid, forming molybdate of ammonia, and this is separated from the residue of undecomposed molybdenite and binoxide of molybdenum, evaporated to dryness, and kept for use. The residue may be again roasted and treated with ammonia. Molybdate of ammonia in solution is the most delicate reagent for phosphorio acid. C>. Ferrocyanide of potassium. — This may be kept in the crystal- lized state and the requisite quantity dissolved in eight or ten parts of water when used. It serves to detect a very trifling amonnt of iron in substances containing chromium and vanadium, when they hare been previously fused with bisulphate of potassa. 7. Sulphide of ammonium. — Pure caustic ammonia is diluted with an equal volume of water, and hydrosulphuric acid gas conducted into it until a solution of sulphate of magnesia mixed with a portion of it remains perfectly clear. This test is necessary to ascertain whether the ammonia is quite saturated. The sulphide of ammo- nium thus made is kept in a glass-stoppered bottle, over which is fastened a piece of bladder or thin caoutchouc. It is used to separate protoxide of manganese and cobalt from magnesia, sesqui- oxide of iron from yttria, and tungstic acid from tantalic and niobic acids, as will b« described in the varions wet analyses. 8. Ferrous sulphate {copperas). Dissolved in water It serves in many cases to precipitate gold from its solution in aqua regia, since it has a reducing action. There are other agents for precip- itating gold, such as oxalic acid, terohloride of antimony, etc., but sulphate of iron is quite suffloient for blowpipe assays. 56 plattner's blowpipe analysis. 9. Sulpliate of copper. It is ol very limited use, but is frequently employed with advantage to detect chlorine in compounds. It is kept In the shape of coarse powder in a wooden box> 10. Acetate of lead, kept in the crystalline state in a wooden box. It is used in testing for chromium, vanadium, and phosphoric acid, when the wet way is partially necessary. 11. Absolute alcohol. It is used with platinie chloride in testing silicates for potassa, and is also required in the examination for baryta and strontia, both to distinguish these earths and to separate them from one another. Section II. QUALITATIVE BLOWPIPE ANALYSIS. OXNEBAL B,VLBB. 59 General Rules. A. General rules, according to which the behavior of minerals and other substances before the blowpipe can be determined, and a considerable proportion of their constituents discovered. The behavior of a substance before the blowpipe is tested partly without and partly with reagents. The testing without reagents is performed : — 1. In a small glass matrass, or a closed tube, to learn whether the substance decrepitates when heated, or yields Tolatile constituents which may be recognized, thus frequently giving indications of the composition of the substance. 2. In an open tube, to detect constituents which oxidize and vola- tilize on ignition with access of air. 3. On coal, to observe what alterations the substance undergoes in the 0. P. and E. F., and whether metallic constituents become volatile, oxidizing and forming a coat on the coal, by which they may be recognized, etc. 4. Either in the platinum forceps, or, if the substance is an easily fusible salt, in the loop of a platinum wire, partly to learn the fusi- bility of the substance, and partly to learn whether it colors the outer flame, and how. The testing with reagents is performed partly on platinum wire and partly on coal. As regards the amount or size of the substance to be tested, it can only be generally remarked that for testing in matrasses and tubes, too little should not be used, while in testing the fusibility and color of the flame only very small splinters oi pieces should be taken, and the same is true in testing substances containing metallic oxides with borax and salt of phosphorus. It is advisable to place the blowpipe-lamp on a sheet of white paper on the table, both to protect the latter and to keep the substances which may fall from being rendered impure, while they can also be more easily found again. 60 plattsteb's blowpipe analysis. a. Examination of the substance without reagents. 1. Testing in a small mateass, ob in a closed glass tubb. "WTien the substance seems free from inorganic combustible bodies, like sulphur, arsenic, etc., a suitable quantity of it is put into a matrass. Fig. 26, A ; if such bodies are present, however, then a closed tube, Fig. 26, B, is employed, which must not be too wide, so that the substance is surrounded with as little air as possible, and no oxida- tion of the combustible bodies may ensue. In both cases the assay is heated in the flame of the spirit-lamp, at first gently, and then to redness if necessary, while all the phenomena are noted. The most usual phenomena occurring in such a test are illustrated by examples in the following pages. Examination of the substance by itself in a smdU matrass. Here belong salts and similar compounds, silicates and aluminates, hydrates, and metallic oxides with their compounds. a. The substance when heated is altered in shape or condition ; decrepitates (e. g., barite, fluorite, calcite, and many other minerals) ; phosphoresces (fluorite, especially the green yariety, apatite, certain calcites, harmotome, cyanite) ; appears to glow as if on fire (glassy gadolinite, orthite, samarsMte, etc.); or changes its color, which reappears in many cases on cooling, while nothing seems to volatilize except, perhaps, a little water (zincite, titanic acid, cerussite, which turns yellow, malachite, siderite, oxide of zinc, which becomes tran- siently yellow). /3. The S. does not appear to alter, but, after longer and more intense ignition, yields volatile constituents. Thus, many peroxides evolve oxygen, which may be easily recognized by placing a splinter of charcoal on the assay, when the coal suddenly enters into active ignition on being sufficiently heated. Hydrates, hydrous silicates, or substances which contain water mechanically combined, yield water, which collects in the neck of the matrass. In case they also contain sulphuric acid or fluorine and are decomposed by heat, the water has an acid reaction on litmus or Brazil-wood paper, after strong ignition ; in the presence of a decomposable metallic fluoride, hydrofluoric acid is also formed, which attacks the glass at a short distance from the assay and renders it dull. 7. The S. fuses without yielding water, and boils when strongly heated. — Certain chlorates, bromates, and iodates. — The oxygen EXAMINATIOIir WITHOUT EEAQEIfTS. 61 evolved reignites a glowing splinter introduced into the matrass, or causes a deflagration when coal dust is thrown on the melting salt. Nitrate ofpotassa and soda behave similarly. 5. The S. fuses, yields much water, which collects in the neck, and becomes solid again. — Salts containing much water of crystallization. —After drying the neck with paper, a strip of litmus paper is intro- duced and the S. more strongly heated. Many salts with weak bases, as alumina, sesquioxide of iron, etc., are decomposed at a red heat, yielding a more or less acid reaction, and sometimes clouding the glass above the assay. The liberated acids may also sometimes be recognized by their odor. e. The S. fuses and yields acid. — Acid salts, the acids of which are volatile when in a pure or hydrated state. — The escaping excess of acid reddens litmus paper. Among the neutral salts with volatile acids only, the nitrates and hyposulphites are generally decomposed; the former yield yellowish-red nitrous acid gas, and the latter color- less sulphurous acid. In certain cases metallic fluorides yield more or less hydrofluoric acid, especially when the compound contains _water, and part of the fluorine is combined with a weak base like aluminium. Should violet vapors, with an odor of iodine, appear, they indicate free iodine. ^. Charring takes place, sometimes accompanied by intumescence and often with a burnt or bituminous odor. — Organic substances. — If the cold, charred residue effervesces with acids, this indicates a combination of alkalies or alkaline earths with the organic acids in the substance. Certain organic acids can be at the same time detected by the odor evolved while charring ; as tartaric acid, ben- zoic acid, etc. The presence of cyanogen compounds is shown by the odor of hydrocyanic acid evolved on adding hydrochloric acid. Sometimes on heating nitrogenous substances ammonia is formed, which can be detected by red litmus paper or a rod dipped in hydro- chloric acid. t). The substance sublimes and condenses in the neck. — Most am- moniacal salts, which either sublime entirely, or, if combined with a non-volatile acid, simply yield ammonia; protochloride of mercury, which flrst fuses and then sublimes; suUhloride of mercury, which sublimes without fusing, becoming yellowish, but on cooling is white again ; chloride of lead, which fuses to a dark, yellow fluid, sublimes partially, and becomes opaque' and white on cooling; oxide of anti- mony, which first fuses to a yellow fluid and then sublimes in lustrous needles, unless more highly oxidized by the enclosed air ; -arsenous acid, which sublimes very easily and condenses in a crystal- 65i PLAITlfEE'S BLOWPIPE ANALYSIS. line state ; tellurous acid, resembling oxide of antimony, but volatil- izing with far more diflBculty, and forming no crystalline sublimate; osmic add, subliming in white drops, and eyolving a penetrating, extremely disagreeable odor; [oxide of mercury yields globules of metallic merctiry, condensed on the glass. — Transl.] Examination of the substance alone in the closed tube. In this way are tested sulphides, selenides, arsenides, teUnrides, and metallic compounds. a. The S. is unaltered, or decrepitates, or fuses and gives nothing volatile, even when heated with the blowpipe until the glass begins to melt Sometimes the glass becomes clouded just above the assay, but this results from a little sulphurous acid acting on the glass. /3. The S. yields a sublimate of sulphur, dark yellow to reddish- brown while warm, pure sulphur yellow when co\di.-~3fetalUc sul- phides containing much sulphur, as iron pyrites, which yields nearly one atom of sulphur ; or combinations of metallic sulphides where one of them has more than one atom of sulphur for one atom of the metal, as chalcopyrite. Sometimes the native protosulphides con- tain a slight excess of sulphur and yield it as a thin, almost white film. y. The S. yields a sublimate of sulphide of arsenic, dark brownish- red to almost black while hot, and reddish-yellow to red when cold. — Native or artificial sulphide of arsenic, and combinations or mix- tures of metallic sulphides and arsenides, which, on giving up all their arsenic contain more sulphur than is required to convert them into protosulphides. S. The S. heated strongly yields a black sublimate, condensing just above the assay, and becoming cherry-red to brownish-red on cool- ing. It is a combination of sulphide and oxide of antimony.' — Sulphide of antimony and compounds of metcdlic sulphides with much sulphide of antimony. e. The S. yields a black, lustrous, metallic, and in part crystal- line sublimate of arsenic. A little sulphide of arsenic sometimes sublimes first. — Skufterudite, chloanthite, etc.; also sulpharsenides, whose liberated arsenic is so far replaced by the sulphur present as to form monosulphides, as arsenopyrite. C. The S. gives a dull black sublimate of sulphide of mercury which becomes red when rubbed. — Native or artificial sulphides of mercury, as cinnabar; also mercuriferous tetrahedrite. EXAMISTATION WITHOUT HEAGEIirTS. 63 rj. The S. yields a lustrous, crystalline, gray sublimate of selenide of mercury. — Tiemannite and lehrhachite. 0. The S. yields a film or coat of small drops of lustrous mercury. — Amalgams, 1. The S. yields at the height of the assay piece a steel-gray, and higher up a red sublimate of selenium. — Umangite. Non-volatile metallic sulphides and such as contain a low proportion of sulphur ; corresponding arsenides, tellurides and some selenides yield uncertain results, or none at all, in the closed tube. 2. EXAMINATIOK OF THE SUBSTANCE IIS THE OPEN TUBE. The substance tested in the closed tube must also be tested in the open tube. The assay is laid near one end of the tube and the spot heated with the spirit-lamp at first, and then, if necessary, with the blowpipe, the tube being somewhat inclined. Generally fragments are used, but substances which decrepitate are first pulverized. The force of the current of air can be regulated by the inclination of the tube. Many hoodies not volatile in the closed tube here absorb oxygen from the current of air and form volatile acids or metallic oxides. Some escape as gases, recognizable by their odor ; others condense as sublimates in the cool part of the tube, at distances from the assay varying according to their volatility. In this roast- ing test too large a piece should not be taken, nor the heat allowed to work strongly upon it too soon, otherwise the greater part of the volatile bodies may sublime unchanged. Should a fragment yield no distinct reaction the substance must be powdered. There are several bcdies which can be recognized with the open tube, even in very compound substances. The principal ones are the following : a. Sulphur. — On treating metallic sulphides, or substances con- taining such sulphides even in trifling quantity, sulphurous acid is found which can be recognized by its odor, or by reddening blue litmus paper at the top of the tube. Sulphides which roast with difiiculty, as blende and molybdenite, with substances containing little sulphur, must be powdered. When the substance contains metals that form volatile oxides peculiar sublimates are formed, the characteristics of which will be described more nearly below. With too large a iragment or too rapid heating sulphur, sulphide of arsenic, or sulphide of mercury, may sublime from the corresponding substances tested, because ai* enough is not present to oxidize them. 64 plattker's blowpipe axaltsis. /?. Selenium. — Selenides and substances containing even trifling quantities of selenium yield a gaseous oxide with the odor of decay- ing horse-radish. If selenium forms an essential ingredient it forms a sublimate of selenium, steel-gray near the assay and red at a greater distance; small, very volatile crystals of selenous acid are sometimes seen still further from the assay. It is best not to take too much substance, so as to have less selenous acid formed. y. Arsenic. — Metallic arsenic and arsenides which contain so much arsenic that, after the formation of basic arsenates in the tube, there remains still free arsenic, yield a crystalline sublimate of arsenous acid, very volatile, and therefore at some distance from the assay. It can be driven off by simply warming it in the tube. When . there is only enough to form basic arsenates, as with speisses rich in cobalt and nickel, a distinct sublimate is not always obtained, even when the substance is powdered. When too large a piece of metallic arsenic is taken, or an arsenide containing very mnch arsenic, too high a heat may easily form a brownish-black sublimate of snb-oxida of arsenic, or even metallic arsenic, and then the garlic odor of the suboxide becomes perceptible. When an easily decomposed sulphide is present a high heat tends to produce a sublimate of yellow or red sulphide of arsenic. &. Antimony.— Metai'^c antimony, antimonides, sulphide of an- timony, and compounds of metallic sulphides containing sulphide of antimony, oxidize and yield white fumes, consisting at first of oxide of antimony, but changing at a high enough temperature under the influence of the air for the most part into a combination of oxide of antimony and antimonic acid. Pure oxide of antimony IS volatile and passes through the whole length of the tube as a fvhite vapor, condensing partly on the upper side of the tube and partly escaping. It can be driven off by heating it again to redness, but a part is very liable to become more oxidized and remain behind. The combination of antimonic acid and oxide of antimony once formed is not volatile and condenses chiefly on the lower side of the tube as a white powder, yellowish while hot. It is mostly formed in roasting sulphide of antimony and its compounds with some metallic antimonides containing separate constituents which are easily oxidizable and evolve considerable heat in oxidizing. In presence of sulphur, sulphurous acid also fo' nu md can be detected as usual. If the substance consists of oxiuc „i antimony, or con- tains free oxide, a portion sublimes unaltered, while part is oxidized more highly and remains behind. When sulphide of lead as well as antimony is present, as in bonrnonite, a sublimate of oxide of anti- mony with antimonate of lead forms, the latter having a light yellow color. EXAMINATION ON CHAECOAL. 65 When sulphide of antimony, or compounds containing much of it, are very strongly »eated, the white coat is likely to be spotted here and there with a reddish or brownish lulphide, which condenses in combination with the oxide, vide p. 62, S. e. Tellurium and tellurides form tellurous acid, which passes as a white yapor through the tube, and soon condenses for the most part into a sublimate, which can be fused into colorless drops by heating that part of the tube with the blowpipe, and is thus distinguished from that produced by oxidizing antimony. Z,. Mercury. — Its compounds with other metals give a sublimate of metallic mercury consisting of small globules, which almost adhere together, and can be united to one drop by striking the tube and turning it slowly on its axis. Sulphide of mercury is by careful heating decomposed into sulphurous acid and mercury, the latter forming a metallic mirror above the assay. By too strong a heat part of the sulphide sublimes unchanged and forms a black sublimate close to the assay, which can be decomposed by carefully warming it. Compounds of chlorine and mercury are very volatile and sublime unaltered. I of lead vields, besides sulphurous acid, a white sublimate of sulphate of lead, chiefly on the under side of the tube, which when strongly heated melts to yellow drops, white when cold. The assay is surrounded with fused oxide of lead, containing sulphate, which is yellow when hot and lighter on cooling. Chloride of lead, and substa:nces containing it, form a sublimate which on repeated heating can only be partly volatilized, with the chlorine liberated from the residue. This consists of oxichloride of lead and fuses like tellurous acid to drops, which are, however, yellow when hot and pearl-gray to white on cooling. Sulphide of bismuffi behaves quite like sulphide of lead. Metallic bismuthides yield oxide of bismuth, which condenses quite near the assay, and is fusible to brown or dark-yellow drops very different from tellurous acid. Sul- phide of molybdenum roasts with difficulty, yielding sulphurous acid, and when powdered and heated strongly for some time, a trifling crystalline sublimate of molybdic acid. 3. Examination oe the substance befoee the blowpipe on chabcoal. When the substance is solid and does not decrepitate, a small fragment can be used, otherwise it must be very finely pulverized. The assay is placed on the side of the coal which shows the edges of the annual rings and near the end turned toward the lamp, a slight cavity being made to receive it.* A gentle 0. F. is directed * Haanel {Trans. Boy. Soc. Canada, Sect. Ill, page 65) forms the coats on plaster tablets ; Goldschmidt (Zeiischr.f. Krystallogr ., etc., XXI. p. 329) on glass strips. [Moses and Parsons (Miner alogy. Crystallography and Blowpipe Analysis, D. Van 6G PLATTXER's BLOWl'IPE AXALVSIS. upon the assay, while the coal is held horizontal and in the direct ion of the blowpipe flame. The flame, being inclined upon the assay at an angle of about twenty degrees, is continued for a short time only, but until a change of color, glowing, swelling, fusion, or the separa- tior. of some Tolatile substance is noticed, or in general any alteration of the substance likely to afford a clue to its character. At tha moment when the blast is stopped the presence of any Tolatile acids, or of sulphur, arsenic, or selenium, is tested by smelling. Since a trifling quantity of arsenic is not thus so easily detected as sulphur or selenium, the assay is also treated with the B. F. when the arsenic odor frequently becomes very distinct While heating the assay various other phenomena are to be noticed ; — as any deflagration after the fusion, which occurs in case of nitrates, chlorates, bromates, and iodates ; whether the coal is coated with yolatilized bodies, far from the assay, or near it ; what color the coat has when hot and cold ; whether it can be volatilized by simply warming it with the flame, or by contact with the flame, and in the latter case whether It colors the outer flame in disappearing. An earthy substance, after being ignited thoroughly, is laid on moistened red litmus paper, to see whether it has an alkaline reaction, which is the case with compounds of the alkaline earths with carbonic, sulphuric, and nitric acids, and of their radicals with chlorine, bromine, iodine, and fluorine. Xostrand Co., New York, 1900) recommend plaster of Paris tablets, 4 in. long, 1 in. broad, and % in. thieli, made by spreading the plaster paste on oiled paper. These are used in the same way as charcoal, and can ilrst be smoked over the oil-lamp flame when white sublimates are to be examined. They give the following, among other coats on plaster : Selenium. Brick-red to crimson. * TeUurium. Deep brown. Cadmium. Dark brown, shading to greenish-yellow, and again to dark brown. Molybdenum. Crystalline yellow and white coat with an outer circle of ultra- marine blue. Also, with bismuth flux (two parts of sulphur, one of potassium iodide, one of potassium bisjilphate). Lead. Chrome-yellow coat. Bismuth. Chocolate-brown coat, with an underlying scarlet ; becoming orange- yellow with ammonia, and later cherry-red. Mercury. Scarlet coat with yellow, but if qu iokly heated, dull yellow and black. Anlim.ony. Orange coat stippled with peach-red. Arsenic. Yellow and orange coat, and not usually satisfactory. Selenium. Reddish-brown, nearly scarlet. TeUurium. Purplish-brown with darker border. Molybdenum. Deep ultramarine blue. — Teassl.] EXAMINATION- ON CHARCOAL. 67 An importaDt means of recognizing various substances is afforded by the coats which they form on the coal at greater or less distances from the assay; but the ashes must not be mistaken for a coat, which they sometimes resemble. This can be guarded against by treating the coal previously with the 0. F., to ascertain neariy the quantity and quality of the ash. The following bodies yield characteristic coats : u. Selenium melts very easily and yields brown fumes in tlie 0. F. and E. F., while a steel-gray coat with a feeble metallic lustre forma near the assay, and a dark-gray, dull coat at a greater distance. This coat can be driven about quite easily with the 0. F., and if treated with the E. F., disappears with a fine azure-blue flame. Dur- ing all these operations a strong horse-radish odor results from the escaping gaseous and colorless oxide. 13. Tellurium melts very easily, volatilizes in fumes, and coats the coal in the 0. F. a" id E. F. with tellurous acid, at no great distance from the assay. The coat is white, but has a red or dark-yellow border, and can be driven about with the 0. F., while it disappears under the E. F. with a green, or in presence of selenium, a bluish- green, flame. y. Arsenic volatilizes without fusing, and coats the coal with arsenous acid in both flames. The white coat appears grayish when thin, partly from the. coal showing through and partly from a mix- ture of suboxide, and is at quite a distance from the assay. It can b« immediately driven off by simply warming it with the flame, and if rapidly treated with the E. F., colors it pale light-blue. During volatilization arsenic evolves a strong alliaceous odor due to the formation of suboxide. 6. Antimony melts very easily; coating the coal with oxide in both flames. The white coat, bluish in thin layers, is not so distant as with arsenic. It can be driven about by heating it gently with Ihe 0. F., and disappears under the E. F., tinging it pale greenish. It is not so volatile as the arsenous acid coat. When antimony is melted and heated to redness on coal and the blast stopped, it remains melted and glowing for some time, evolving dense, white fumes, which condense partly on the coal and finally surround the button with white, pearly crystals. This results from the oxidation of the metal by the air, forming oxide of antimony and evolving so much heat that the fusible metal is kept fluid, until covered with crystals of oxide. i. Tliallium melts very easily, forming at some distance from the 68 platxxee's blowpipe analysis. assay a moderate white coat of oxide, which can be driven off by simple wanning, and tinges the E. P. green. The melted button, which also tinges the flame strongly gteen when touched by it, remains, after setting the coal aside at rest, for some time fluid in consequence of continuing oxidation, and occasionally a brown coat is observed very near the metal, which is perhaps peroxide. ^. Lead melts easily, coating the coal with oxide in both flames. When warm, this is dark lemon-yellow, when cold, sulphur-yellow and bluish-white in thin layers. The yellow coat is pure oxide of lead, and the bluish-white one, carbonate. When the coal is heated to glowing, the coat changes its place, because the oxide is reduced and the metal immediately volatilized and reoxidized. The flame is thereby colored azure-blue. r,. Bismuth fuses very easily, giving a coat of oxide, which is dark orange-yellow when hot and lemon-yellow when cold, being yellow- ish-white in thin layers. The yellow coat is pure oxide, and the yellowish-white one, which is at the greatest distance is carbonate with some oxide of bismuth. It can be driven about on the glowing ooal like lead, but does not color the E. P. during the operation. 5. Cadmium melts very easily and bums in the 0. P. with a dark- yellow flame and brown fumes, coating the coal with oxide rather near the assay. Xearest the assay the coat is thick, crystalline, and of a very dark, almost black color, further off, it is reddish-brown, and finally orange-yellow in thin layers. It can be easily reduced and driven about with either flame, but gives no coloration. Beyond the furthest limits of the coat the coal sometimes shows a variegated tarnish. I. Indium fuses easily, yielding a coat which is very near the assay, dark-yellow while warm, but yellowish-white on cooling, and is driven off with difficulty by the R P., to which it imparts a f ne violet tinge. ji. Zinc fuses easily and bums in the 0. P. with a strongly lumin- ous, greenish-white flame and thick white fumes, which coat the coal with oxide. The coat is rather near the assay, yellow while warm and white when cold. It becomes luminous under the 0. F., but is not volatilized, because the glowing coal cannot reduce it. It is volatilized only slowly even by the E. P. >.. Tin fuses easily and in the 0. P. is covered with oxide, which can be mechanically blown away ; in the K. P. the metal becomes lustrous and coats the coal with oxide, which is pale yellow while warm and luminous under the 0. P. On cooling it becomes white; EXAMINATION ON CHARCOAL. 69 It is SO close to the assay that it borders directly upon it and cannot be volatilized by either flame, but is slowly reduced to metallic tin in the K. P. M" Molybdenum, in the powdered state, is infusible, but heated with the outer flame gradually oxidizes and coats the coal at a little distance with molybdic acid, which in many places, and particularly nearest the assay, condenses in transparent crystalline scales, but beyond in a pulverulent state. While hot the coat is yellowish, but white on cooling. On touching only its surface with the yellow flame a very fine dark-blue color of molybdate of molybdenum is formed ; if, however, the heat was so great as to cause the coal to glow, the latter when cool has a dark copper-red, metallic appear- ance, from binoxide of molybdenum, which has been reduced from the molybdic acid and is not volatile. In the K. F. metallic molyb- denum is unaltered. V. Silver fused for some time with a powerful oxidizing flame gives a slight reddish-brown coat of oxide. In combination with a little lead there is first a yellow coat of oxide of lead ; but afterward, when the silver is more free from lead, a dark-red coat forms outside of the first. When a little antimony is present there results at first a white coat of oxide of antimony, which becomes red on continued blowing. In case the silver contains a little of both metals, a copi- ous crimson coat is formed after most of the lead and antimony are volatilized. This coat is obtained sometimes in testing rich silver ores on coal. Many substances yield coats similar to those above, and regard must be had to theie in order to avoid mistakes and confusion. They are : certain sulphides, chlorides, bromides, and iodides, which yield a white coat. Sulphides of potassium and sodium^ having been formed in the K. S". from the sulphates, volatilize and are oxidized, giving a white coat of neutral sulphates, which does not form, however, until all of the sul- phate has sunk into the coal and been reduced. Sulphide of potassium being more volatile than sulphide of sodium, forms a thicker coat. When the coat is touched by the flame it disappears with a bluish-violet color in case of potassa and a reddish-yellow color in case of soda. Sulphide of lithium behaves similarly and colors the flame Durplish-rsd, while the newly-discovered caesium and rubidium sulphides probably show similar reactions. Sulphides of lead and bismuth give two coats, one more volatile and white, consisting of sulphate, and one nearer the assay, consisting of oxide of the metal in hand, which can be known by its color both while hot and cold. The white lead coat disappears with a blue flame, and both it and the bismuth coat leave a spot of yellow oxide where the coal was made to glow. Sulphides of antimony, zinc, and tim yield only oxides, either volatile in case of antimony, or fixed in case of zinc and tin. Many chlorides volatilize and yield a white coat. W ith chlorides of potassium, sodium, and lithium the coat is not formed until they have fused and sunk into the coal. Chloride of potassium gives the thickest coat and lithium the feeblest, which is also grayish-white and not pure wliite. The chlorides of ammonium, mercury, and antimony, TO plattxeb's blowpipe analysis. ToIatilizB without fusing, and those of zinc, lead, bismuth, and tin, first fuse and then give t wo coats ; one of the chloride of the metal, white and more volatile ; the other of the oxide, and less volatile. Some of these chlorides color the E. F. : that of potas- sium bluish-violet, of sodium reddish-yellow, of lithium purplish-red, of lead blue; the others disappear without coloring it. Chloride o/cojiper also fuses and colors the flame mtense azure-blue, and on continued blowing part of the assay volatilizes with white fumes, which smell strongly of chlorine, while another, part forms three coats differing in color; that nearest the assay is dark-gray, the next is dark-yellow to brown, and the furthest is bluish-white. When such a coat is touched with the flame it partly changes its position with an azure-blue coloration. Among the bromides and iodides, which behave quite like the chlorides, the bromides and iodides of potassium and sodium deserve especial mention here. They fuse, sink into the coal, and then volatilize with white fumes, which partly form a coat rather far from the assay. This disappears under the R. F., coloring it bluish-violet in case of potassium and reddish-yellow in case of sodium. 4. ExAinxATiox OP the substances as to fusibility and thb COLOK WHICH THEY IMPAET TO THE OUTER FLAME. a. Testing the fusibility of substances. Metals, metallic compounds, snlpliides, or other substances which appear to contain ingredients that would attack platinum, are heated on charcoal with the E. F. or within the blue flame. A small piece is used for the assay. Most of the metals can be fused in this way, but they generally oxidize more or less and gradually volatilize; among the noble metals, gold and silver form a;i exception, although silver is not altogether fixed, p. 68. The other noble metals ■.platinum iridium, jjallndium, rJiodiuvi and osmium, are infusible on coal, whether in powder, beads, or scales. Osmium is oxidized to osmic acid, however, in the 0. P., and volatilizes as such ; while platinum, in very fine wire, or in very thin and pointed strips, can be melted witli a good 0. F., as stated on p. 14. Among the other metals, the oxides of which can be reduced in the E. F., especially by adding soda or neutral oxalate of potassa, tungsten, nickel, cobalt, iron, and molybdenum are likewise infusible on coal ; the latter is gi-adually converted into molybdic acid in a pure 0. F., p. 69. Xickel and cobalt can, however, when in very thin, pointed strips, be fused to malleable buttons with the tip of the blue flame ; fine iron wire likewise melts, but gives a brittle button of magnetic oxide. The compounds of metals with arsenic are generally fusible, even in case of infusible metals. So are the metallic sulphides, but several of them are gradually volatilized, evolving sulphurous acid and EXAMINATIOJT AS TO FUSIBILITY. 71 coating the coal, p. 69. Among the natural sulphides, those of man- ganese, molybdenum, and zinc are infusible. The fusibility of the metallic oxides must be tested with a pure 0. F. Only a few of them are fusible, including the following : oxide of copper; oxide of antimony, which volatilizes after fusion; oxides of bismuth and lead, both of which are reduced to metal by the glowing coal after fusion. When the substance is earthy, or a silicate, or in general such as will not attack platinum, and is also in a firm state, a thin splinter, or small piece having a point or sharp edge, is held in the platinum forceps with the edge in the hottest part of a pure 0. P. If, however, the substance has decrepitated when tested in the matrass, a suitable fragment of the heated substance is selected. For substances which crumble to powder or cannot be divided into sharp fragments, the method proposed by Berzelius for minerals that fuse with great difficulty is employed. The substance is rubbed fine with a little water in the agate mortar, the thin paste laid on coal, dried, and heated B. B., quite strongly toward the end, until the mass lies loosely on the charcoal as a thin coherent plate, which can be held with the platinum forceps in the 0. P. Substances already in a powdered state can be similarly treated. By heating the edge or point of the assay in a pure, suflBciently strong 0. P., so that there is a slight interval between the tip of the blue flame and the assay, it will soon be seen whether the substance Is fusible or not. Infusible substances retain their sharp edges unaltered, which can only be ascertained by using the magnifier ■ chose of diflacult fusibility are rounded on the edge, while the easily fusible ones melt to a bead. Substances may be divided according to their fusibility into : 1. Such as fuse to a bead ; a, easily ; b, with difficulty. H. Such as fuse only on the edge ; a, easily ; b, with diflSculty. 3. Such as are infusible. Von Kobell has arranged a scale by which the fusibility of the substance may be compared with that of certain minerals of known fusibility, and thus more exactly determined : 1 . Stibnite, fusible in the flame cf a candle in coarse splinters ; 2. NatroliU, fusible in the candle flame only in fine splinters, easily fused before the blowpipe in quite coarse fragments ; 3. Ahnandite or iron alumina garnet, infusible in the candle flame, quite fusible before the blowpipe in coarse fragments. 4. Actinolite, fusibility notably less than almandite and greater than orthoclase, fusible in coarse splinters ; 72 plattxek'.s blowpipe analysis. 5. Orthodaee, fusible in fine splinters ; 6. Bromite, only rounded on the edges in very fine splinteis. Splinters of the abore minerals, varying in fineness, may be kept on hand for com parison ; the various gradations of fusibility are expressed by decimals, thus : fusibility 2.7-2.8 denotes that the mineral is somewhat more fusible than almandite. Some minerals infusible in the O. F. can be fused on the edges in the E. F., or even in the tip of the blue flame. Thus, Tiematiie loses some of its oxygen in the R. F. and is then fusible on the edges ; magnetite becomes more highly oxidized and is infusible in the O. F., while it can be fused in the E. F. ; siderite when ignited in the matrass is converted into proto-sesquioxide of iron, at the expense of the carbonic acid driven ofi^, and then behaves like magnetite ; chromite, titanic iron, franklinite, and the silicates of protoxide of iron also act similarly. Substances containing oxides must therefore always be tested at first with a pure O. F., and the K. F. only used when they appear infusible, so as to ascertain whether any diiference is to be perceived. Many minerals when strongly heated alter in form and color without fusing ; some swell, Uke borax; others give cauliflower-like ramifications, part of them fusing after swelling up, while others remain puffed up without fusing. Some minerals fuse and froth up, giving a blebby glass filled with babbles, which cause it to appear opaque, even when the glass is really transparent. While these reactions are seldom to be regarded as indioating definite sub- stances, they Irequently aid the determination, especially in tests of minerals. ^. Examination of the substance as to the color it imparts to the exterior of the blowpipe flame. There are jnany bodies which color the outer flame more or less when heated with the tip of the blue flame. When the color is distinct and sharply deflned it serves frequently as a characteristic means of immediately recognizing the constituents of the substance. This test may frequently be combined with that for the fusibility, because it is generally made with small splinters of hard minerals,, held in the platinum forceps, or in case of powdered or decrepitating substances, with a crust prepared with water, as directed on p. 71. The splinter, or crust, being first tested in the platinum forceps with regard to its fusibility, its sharp point or edge is then brought into direct contact with the tip of the blue flame, so as to see whether the exterior pale-bluish fiame is colored.* With many substances the slightly luminous envelope of the blue flame streams past the assay without change of color, but with many other substan- * Sometimes a better result is obtained by bringing the assay against the edge of the flame, and using a weak rather than a strong blast. Occasionally two colora- tions may appear ; one at the top or edge of the flame, the other in the interior cora. COLORATION OF THE FLAME. 73, ces the outer flame is first somewhat enlarged, in consequence of a trifling amount of water or carbonic acid, and frequently colored a feeble reddish-yellow, but this tinge disappears afterward, giving place to a very different one, which is produced by volatilizing constituents. There are also substances which produce the color immediately, and if the assay fuses with difficulty, or not at all, the color frequently becomes more intense after continuing the blast longer. When the assay was fused to a bead in testing its fusibility and no longer produces a distinct color, a fresh piece should be used, because a fused bead does not produce so intense a color as a fusing point or edge. Many substances produce no color, or only an indistinct one, although containing a constituent which has the quality of coloring the flame when free ; as substances containing phosphoric acid, boracic acid, or lithia, in small quantity. The finely-powdered substance is then treated on platinum wire, with special fluxes, or after being moistened with sulphuric acid. Easily fusible substances are tested on platinum wire, but it is always well to take only a small quantity, which can then be heated strongly, and will produce a more intense color than a larger amount. To fix the substance on the wire this is heated and brought into contact with the substance, or first moistened with distilled water if the substance will not adhere to the glowing wire. Hydrous sal-ts adhere very easily to the hot wire, but anhydrous ones only with difii- eulty, if at all. Metals and their combinations, sulphides of the metals and easily reducible oxides in the powdered state, must be treated on charcoal. If they are massive a fragment the size of a hemp-seed i» used, and if in powder, a quantity which would not be larger when melted. In either case the assay is laid in a quite shallow cavity on the long side of the coal, and the blue flame is directed immediately upon it, when, if the substance possesses the quality of coloring the flame, the assay will be surrounded with a distinct and more or less intensely colored flame. If the substance forms a coat on the coal this can likewise be treated with the blue flame, but it is better then to employ a more spreading E. P., so as to observe distinctly the color which the coat produces in disappearing. All experiments on the color of the flame, in whatever way con- ducted, succeed better either in a darkened room, or, if in a light room, when the operator places himself before the lamp, so that the daylight may not fall directly upon the flame, since in this way only can the exterior, feebly colored envelope of the blue flame be most plainly seen. (A black back-ground is best. — Transl.) 74 PLATTXER'S BLOWPll'E ANALYSIS. Too mDch care cannot be exerciacd in these experiments, to avoid an impure flame caused by soda, since even the minutest amount of a soda salt renders the experiment useless, because soda colors more intensely than any other body. The assay must therefore be bandied as little as possible with the fingers, and if pulverized in the mortar with water, care must be taken to cleanse this from any borax or soda by washing. The platinum wire should also be pure and impart no color to the flame when tried by heating it in the point of the blue flame. Should it show a reddish-yellow color, which may be caused by chloride of sodium from the moist fingers, this will disappear after continuing the blast some time ; but if a very trifling quantity of some previously tested substance containing soda still adheres to it, the intense reddish-yellow flame will be permanent and the wire must be cleansed, either by warming it with hydrochloric acid in a test tube and then washing it with water, or by fusing a little bisulphate of potassa on it and then shaking this ofi". The colors imparted to the outer flame, by heating various bodies with the blue flame, are yelloio, violet, red, green, and Hue. 1. Yellow. — All soda salts fused in contact with the point of the blue flame color the outer flame intense reddish-yellow. A large admixture of other salts, the bases of which color the flame less intensely than soda, does not conceal this reaction. Small splinters of silicates containing soda, strongly heated or fused in the forceps, color the flame more or less strongly, according to the proportion of soda in them. 2. Violet. — Potassa and most of its salts, witb the exception of borate and phosphate, as well as salts of rubidium and caesium and \ he compounds of indium, tinge the outer flame with a bluish- violet color. The three latter elements being exceedingly rare and occur- ring in very minute quantities, the most important color is that pro- duced by potassa. Even the minutest mixture of a soda salt alters this reaction, so that, although a feeble violet color can be seen quite distinctly in the core of the flame, the intense soda flame is appar- ent at the edge. If the amount of the soda salt rises to several per cent., the potassa reaction is entirely concealed, and in such cases the colored flame is viewed through blue cobalt glass, or a solution of indigo, or of permanganate of potassa to recognize the potassa flame, as will be more particularly described under potassa, p. 103. The potassa reaction is likewise concealed by lithium, unless present in very small quantities. Silicates containing considerable potassa only produce the violet flame when perfectly free from soda and lithia and rather easily fusible on the edges. 3. Red. — There are three bodies which produce a red flame: lithia, strontia, and lime. a. Lithia and its salts produce a carmine-red flame, the chloride coloring most intensely. Notable admixtures of potassa salts do not COLORATION OF THE FLAME. 75 prevent the reaction, but produce at most only a violet shade; quite small quantities of £oda salts, however, suffice to change it to a yel- lowish-red flame. AVith a considerable mixture of a soda salt the flame hecomesonlyin tense reddish-yellowand cannot be distinguished from a pure soda flame. The means of distinctly recognizing lithia in such cases are given under lithia, p. 110. Vide also silicates, under lithia. /3. Strontia. — Chloride of strontium produces immediately a crimsoL flame. Many strontia salts, as the carbonate, strontianiie, and sul- phate, celestite, when heated in the forceps, color the flame at first pale-yellowish, but afterward crimson, pp. 116, and 117. In presence of considerable baryta the strontia flame may be entirely concealed by the green baryta flame. y. Lime. — Chloride of calcium produces a red flame, less intense than chloride of strontium and mixed with yellow. Fluorite fuses it first and colors the flame yellowish, but as the fused mineral is altered to basic fluoride of calcium and becomes less fusible, the flame changes to an intense yellowish-red lime flame. Most pure calcites and compact lime-stones yield a pale-yellowish flame at first, but as ihe carbonic acid is expelled a red flame appears, which is, however, less intense than with the two salts above named. The presence of baryta prevents the reaction. Gypsum and anhydrite produce at first only a feeble yellowish flame, but afterward a slight red flame. Among the silicates wollastonite alone produces a feeble red lime flame. 4. Green. — Several bodies produce a green flame, viz., o%ide of copper, antimony, iliaUium, horacic acid, tellurous acid, baryta, molybdic and phosiihoric acids. It. Oxide of copper, both alone and in combination with acids which themselves produce no coloration, gives an emerald-green flame, viz., carbonate and nitrate of copper. Silicates and other compounds containing oxide of copper also generally produce a very intense green, as dioptase, chrysocolla, and the same is obtained when copper forms an unessential ingredient, as in turquois and many specimens of smith sonite. Combinations of copper and iodine also cause a very intense green flame, and metallic copper melted on coal and not entirely protected from the air is oxidized and yields an emerald-green flame. /3. Thallium. — When melted on coal and touched with the tip of the blue flame this metal is surrounded by a green flame, p. 67. Its salts give an intense green flame. y. Boracio acid. — Both the native and artificial acid produce an apple-green flame, but if not quite free from coda, the green 76 piattner's blowpipe analysis. flame is mixed with more or less yellow. Seyeral of the minerals containing boracic acid, as datolite, horacite, produce a distinctly yellowish-green flame, while others must first be finely pulverized and treated on platinum wire with sulphuric acid. Borax produces a yellow flame, on account of its soda, but if melted, pulverized, moistened with sulphuric acid, and heated, an intensely gi*een flame is produced for a short time, which changes to yellow again as soon as the salt is decomposed or all the free sulphuric acid gone. Another and very sure means of detecting boracic acid in minerals, by its green flame, has been proposed by Turner, and will be spe- cially described under boracic acid, p. 316. S. Tellurous acid fuses, fumes, and colors the flame green. The tellurous acid deposited on coal during the treatment of a tellurium ore disappears with a green color, or in presence of selenium a bluish green color, p. 67, if treated with the blue flame. e. Baryta. — Chloride of barium yields at flrst a pale-green flame, which afterward becomes intense yellowish-green. The color is finest when very little of the salt is employed. Carbonate of baryta, witherite, and sulphate of baryta, barife, also color the flame yellow- ish-green, but less intensely. The reaction is not prevented by the presence of lime, as is shown by the mineral barytocalcite, p. 114. ^. Molybdic acid, or binoxide of molybdenum, gives a yellowish- green flame, in which the yellow predominates more than in the baryta flame ; molybdic acid volatilizes meanwhile. When the edge cf a thin scale of molyldenite is held in the flame, it at once pro- duces a yellowish-green molybdic acid flame, without fusing. ^. Phosphoric acid. — Fuchs and Erdmann have shown that phos- phoric acid, phosphates, and minerals containing phosphoric acid, give a bluish-green flame; some of themselves, others only after being moistened with sulphuric acid. This reaction is so sure, that with proper care, even very small quantities of phosphoric acid can be detected in minerals, when they are finely pulverized, moistened with sulphuric acid, and treated in the loop of a platinum wire. The same is true of salts which alone give no phosphoric acid reac- tion, in consequence of soda or some other intensely coloring ingre- dient. If these salts contain water, it must flrst be expelled by ignition or fusion on coal, and when soda is present, although the flame is quite distinctly bluish-green so long as the phosphoric acid is liberated by the sulphuric acid, yet afterward an intense soda flame succeeds. As the bluish-green flame lasts but a short time, the assay must be closely watched as soon as it is brought near the blue flame. Pyromorphite, owing to the oxide of lead present, gives a blue flame, the tip of which has a persistent green color. EXAMINATIOK WITH EEAQENTS. 77 ^. Antimony. — The metal or sulphide, fused on coal within the blue flame, yields a yery pale greenish coloration; the resulting white coat of oxide treated with the blue flame disappears with the same coloration. Ammonia and nitric aoid, especially when combined, volatilize with a bluish- green flame, which is quite similar to that of phosphoric aoid, although feeble ; so do chloride of ammonium, etc. 5. Blue. — A blue flame is produced by selenium, arsenic, lead, chloride and bromide of copper. a.. Selenium fused within the blue flame on coal volatilizes with an intense azure-blue flame. The coat formed by it shows the same reaction, p. 67. fi'. Arse7iio. — Metallic arsenic and arsenides of the metals which produce no coloration themselves, viz., niccolite, smaltite, etc., are surrounded with a blue flame when heated on coal. A very volatile coat of arsenous acid is also formed, which, if quickly touched with the blue flame, likewise disappears with a very distinct light-blue color, p. 67. Arsenates of bases which themselves do not color the flame; viz., annalergite, erythrite, pitticite, etc., heated in the forceps, give an intense light-blue flame, which is also frequently produced even when the base also causes a colored flame, as with arsenate of lime, pharmacolite. y. Lead. — Melted on coal metallic lead is surrounded by an azure- blue flame and yields a coat of oxide, which if driven about gives an azure-blue flame also, p. 68. Most lead salts treated on platinum wire, or in the forceps, give an intense azure-blue flame. S. Chloride and bromide of copper. — The native and artificial chlo- rides strongly heated color the flame intense azure-blue, but after- ward green from oxide of copper. Cupriferous substances, as metal- lic oxides and slags, when finely pulverized and moistened with hydrochloric acid, color the flame azure-blue for a short time. Bro- mide of copper, similarly treated gives at first a greenish-blue flame, but afterward the green oxide of copper flame. b. Examination of Substances with Reagents. Eeagents are used in testing substances which without them yield no certain indications of their composition, and the reagents best suited for this purpose are borax, salt of phosphorus, soda, and solu- tion of nitrate of cobalt. Substances which the preceding tests have shown to be free from combustible bodies, can be at once treated with the above reagents; sulphides and arsenides of the metals, and oxides mixed with them. 78 plattner's blowpipe analysis. must be prepared in most cases by removing the sulphur and most of the arsenic, and by thoroughly oxidizing the ■i.ietals. This is done by Roasting the Substance on charcoal. Thirty to fifty milligr., more or less, as required, of the yery finely pulverized substance is pressed down with the spatula or knife-blade into a thin layer, in a quite shallow cavity scraped on the coal, and is treated at first with a feeble 0. F., so that the assay is touched only by the tip of the outer flame and heated to low redness. Most of the sulphur then volatilizes as sulphurous acid, the metals are oxidized, and, since sulphurous acid has a tendency to change into sulphuric acid at the expense of already formed or forming metallic oxides, these are converted partly into sulphates, and also, in presence of arsenic, into arsenates. As soon as the fumes of sulphurous acid can no longer be smelled, a feeble K. F. is employed, which reduces the sulphates and arsenates for the most part, while the arsenic is more or less completely volatilized, according to the ease or difiiculty with which the arsenides yield up their arsenic. When the arsenical odor ceases the assay is once more ignited with a feeble 0. F., gener- ally causing a slight odor of sulphurous acid, and then the assay, which should only be baked together, but not sintered, and much less fused, is turned with the spatula and the other side treated alternately with the 0. F. and E. F. After roasting this side the coherent mass is powdered in the agate mortar, and since it is not free from disseminated sulphates and arsenates, of may even, if not carefully enough roasted, still contain a trifling amount of sulphides and arsenides, it is replaced on the coal and again roasted on both sides. Sulphur is frequently more easy to expel than arsenic, but there are metallic sulphides which can be converted for the most part only into sulphates, as sulphide of lead ; it is also not very easy to convert sulphide of copper into oxide quite free from sulphate, by roasting, although continued heating alters the sulphate into toler- ably pure oxide. By mixing the roasted assay in the mortar with an equal volume of carbonate of ammonia and again feebly igniting the mixture on coal in the 0. F., sulphate of ammonia volatilizes and leaves the oxide of copper free from sulphuric acid. Arsenic often remains obstinately combined as acid with certain oxides, especially protoxides of nickel and cobalt. Antimony volatilizes partly at the outset as oxide, while the remainder is converted into a fixed combination of oxide of antimony and antimonic acid. If the substance contains much sulphide of antimony, lead, or any other easily fusible sulphide, and is liable to sinter, as with tetrahedrite, EXAMIXATIOX WITH BORAX. 79 bournonite, etc., it is well first to expel the volatile sulphides hy fusion on coal, recognizing them by the coats formed, and to roast only tlie residue, after again pulverizing it. To avoid the escape of arsenical fumes, substances containing much arsenic may first be ignited in an open glass tube, when the greater part of it sublimes as arsenous acid and some of the sulphur volatilizes as sulphurous acid, after which the assay is roasted on coal. A well roasted assay must give no odor of arsenic or sulphurous acid while glowing, must have a dull appearance, and must admit of being easily crushed to a very fine powder; otherwise it must be pulverized and further roasted. When treating selenides, tellurides, or autimonides containing little or no sulphur, and which have heen recognized as such by the preceding tests, it is seldom necessary to roast them, because in most cases the selenium and volatile metals are volatilized by fusing them alone on coal for some time, and the fixed metals can then be very easily recognized by fusion' with fluxes in the 0. F. Telluride of silver forms an exception, inasmuch as it yields only a part of its tellurium, and a silver button free from tel- Ittrinm cannot be obtained in either flame. 1. EXAMIN-ATION' OF SuBSTAKCES WITH BOEAX. This test is made either on platinum wire or on coal. Earths and metallic' oxides are generally treated first on wire in the 0. F., and then in the E. F., on wire or on coal ; roasted sulphides and arsenides apparently free from arsenate of cobalt and nickel are likewise so treated ; but substances containing much of those arsenates are treated at once on coal. The part which the borax plays as reagent has been explained on p. 4.fi. The testing of substances with borax on platinum wire is per- formed as follows : The heated loop is dipped in borax, and the ad- hering salt melted to a glass in the 0. F., repeating the operation until the bead corresponds to the size of the loop. The bead must be quite colorless, both when hot and cold ; if otherwise, it must be- removed by heating it strongly, and then shaking it off into a small porcelain vessel, by striking the hand holding it smartly upon the table. The success of the operation depends upon the rapidity of the manipulation and the firmness with which the wire is held in the hand. The substance may then be attached to the cold, moistened borax bead, or at once caused to adhere to it while melted, and is in either case fuseid with it in the 0. F. It must now be observed whether the body dissolves with ease or difficulty, with or without efferves- 80 PLATTXEil'ri BLOWPIPE ANALYSIS. cence, whetiier the bead with the dissolved substance is colored when held against the daylight, and whether this color remains the same, or becomes lighter on cooling, as well as whether the bead remains clear, or becomes opaque when cold. Some bodies give a clear glass up to a certain degi'ee of saturation, which also remains clear when cold, but by gently heating it, espe- cially by a quick intermitting blast, the bead becomes opaque, milk- white, or opalescent, and sometimes colored. This operation is called flaming, and generally produces a result only with such bodies as yield a glass, which, after perfect saturation, is transparent while fluid, and becomes enamel-like of itself at the moment of solidifica- tion. This is the case with the alkaline earths, yttria, glucina, zirconia, oxides of cerium, tuntalic and titanic acids, etc. When a borax bead shows the above plienomeuon, it is said that the bead " Itccovieis ojiaque by flaming," whereby, for the most part, micro- crystalline compounds are formed in the bead.* When treating a substance containing much of a coloring oxide, or several such oxides, but little should be dissolved at once, in order to avoid too dark a glass, the color of which could not be recognized. When the glass is too darkly colored, it is pressed out while soft, or if this is not enough, some of it must then be broken off and the residue fused with fresh borax. The color of a bead may be examined with or without a magnifier, * This reaction, already notei^l by Berzelius, has recently been the subject of frequent exact examination. First Emerson {Proceed. Amer. Acad, of Arts and Srimces, vol. 6, p. 476) called attention to the crystalline nature of such separations in the beads. G. Bose i.Vimatsberichte d. Berl. ATcad. d. Wissensch. 1867, pp. 129 and 450 ; also Erdm. Journ., vol. 101, p. 217, and voL 102, p. 385) later announced the [leeuliar behavior of titanic acid and ferric oxide under thess circumstances, and recommended it as a characteristic reaction for the former. Sorby likewise (fjhem. yews, vol. 20, p. 18) contributed somewhat about such crystal formations. This subject has been comprehensively worked out by Wunder (Erdm. -Journ. f. pr. Cliemie, X. F., vol. 1, p. 452; vol. 2, p. 206, and vol. 4, p. 339), to whose articles especial reference must here be made. Very recently Doss has occupied himself with these tests (JV. JT>.f. Mia., 1894, voL 2, p. 147), and has also given a very comprehensive reference to the literature of the subject. — The beads should be examined under the microscope with a linear magnifying power of 80 to 100, in order to observe the interesting phenomena. The beads should not be thicker than 1 to IJ^ millim., and are made on not too stout platinum wire, bent to a circle of about 3 millim. diameter Even the beads made on the usual platinum wire will answer it the sufficiently saturated and still clear glass is pressed flat with the forceps and a feeble blue flame is intermittently di- rected upon the centre of the resultiijg disk, until the spot shows a cloudiness. EXAMINATION ■WITH BOKAX. 81 JiTid it must he borne in mind that the color with many substances is different when hot and cold. The substance having been dissolved in the 0. P., the glass is treated in the E. P., but with such a blast that no soot shall be ■deposited upon it. When metallic oxides or acids are present, which are reduced from borax only with difficulty, or not at all, viz., ses- quioxides of cerium, manganese, iron, uranium and chromium, protoxide of cobalt, titanic and tungstic acids, etc., the bead may be ■treated at once on the platinum wire ; but if there are easily redu- cible oxides present, as those of zinc, nickel, cadmium, lead, etc., the wire would be injured, and the bead must therefore be shaken from it and reduced on charcoal. The bead is placed in a cavity on ooal &i\d treated with a pure E. P. that deposits no soot. After blowing one or two minutes, the glass is pinched with the forceps and drawn out a little, so that its color can be plainly seen. If the dissolved ■oxide was combined with a notable amount of sulphuric acid, sulphide of sodium is liable to form, which colors the glass yellowish- red, especially when slowly cooled, and a false result may be obtained unless this is borne in mind. If the glass contains easily reducible oxides of volatile metals^ a coat of these oxides is formed on the coal, as with glass containing much oxide of antimony, zinc, indium, cadmium, bismuth, or lead. In some cases a small bit of pure tin, as large as a pin-head, is placed beside the bead, and both are fused for a moment in the E. F. The tin has a great affinity for oxygen, and absorbs it partially from the metallic oxides in the glass, dissolving itself to a colorless bead, wliile the oxides are reduced to the lowest stage of oxidation, and produce a distinct color, which frequently appears only after they -are quite cold.* AVhen copper or nickel are to be perfectly reduced from a borax bead containing few or no other easily reducible oxides, some metallic lead may be with advantage added to the bead on coal ; the metal distributed through the bead then unites into one button with the lead, and the glass can afterward be further tested for non- reducible oxides on platinum wire. Many metallic arsenides, as niccoiite, smaltite, cobalt and lead speisses, etc., in which arsenide of nickel or cobalt forms a chief ingredient, can be immediately treated with borax on coal without * Hirsohwald uses instead of metallic tin solid stannous chloride, which he adds in small grains directly to the bead on wire. 82 PLATTXEK S BLOWPIPE AXALISIS. roasting, since they generally fuse easily. The method of proceeding will be given under nickel and iron. The following table, similar to those arranged by H. Bose, Aus- fuhrl. JSayidiuch d. analyt. Ohemie, toL i., p. 795, and Scheerer, Ldth' rohrbuch, 2d edition, p. 44, gives a convenient surrey of the colors .'mparted to borax by the metallic oxides and acidi, in both the oxidizing and the reducing flames : — TABLE L The Metallic Oxides and Acids arranged with reference to the Colors which they impart to the Borax Bead. WITH BOKAX IK THE OXIDIZING FLAME PEODUCB: a. Colorless Beads, Hot and cold: Silica, Alumina, Binoxide of Tin. Baryta, Strontia, Lime, Magnesia, Glucina, Yttria, Zireonia, Thoria ; Oxides of Lanthanum and Silver ; Tantalic and Tellurous Acids. Titanic, TucRStic, and Molybdic Acids; Sesquioxide of Didymium; Oxides of Indium, Zinc, Cadmium, Lead, Bis- muth, and Antimony. When highly saturated opaque (white) by flaming. AVhen feebly saturated. b. YeUow Beads. Hot: Titanic, Tungstie, Molybdic, i _,. , . ,, i, ^ , ,. , , 1-- , ■ . ', A. ■ , / When highly saturated ; on cooling color- and Niobic Acids, Oxides 'r , " / ^ L ■ , ,, , . 1 less : and opaque by flaming, of Zin3 and Cadmium. 1 Oxides of Lead, Bismuth, / _^, ..... ^ , . , ,. >^Aii.c ^ i^ , , T yrjig^ highly saturated ; colorless on coohug, and Antimony. i Sesquioxides of and Iron ; Tranie ij.\- ^ ide. I '^i"=o°l"'g- Sesquioxide of Chromium (freely saturated) ; when cold, yellowish-green. Vanadic Acid. Cerium i , . I When feebly saturated ; more or less colorless c. Red to Brown Beads. Hot: Cold: f Sesquioxide of ferium ; on cooling, yellow, enamel-like by flaming. I " " Iron ; on cooling^ yellow. J " " Uranium; on cooling, yellow ; enamel-yellow by flaming. I " " Chromium; on cooling, yello^v^sh-green. i " " Iron containing Manganese; on cooling, yellowish-red. f Protoxide of Nickel (reddish-brown to brown) ; violet while hot. Sesquioxide of Manganese (violet-red) ; violet while hot. j Protoxide of Nickel containing Cobalt (with little Cobalt, violet-brown); violet while hot. EXAMIITATION WITH BORAX. 83 d. Violet Beads {amethyst-colored). Hot: Protoxide of Nickel ; on cooling, reddish-brown to brown. Sesquioxide of Manganese ; on cooling, red inclining to violet. Protoxide of Nickel containing Cobalt ; when cold, inclining to brownifh With much Cobalt, violet when cold also. Protoxide of Cobalt containing Manganese ; the same on cooling. e. Blue Beads. Hot : Protoxide of Cobalt ; the same on cooling. Cold : Oxide of Copper (when highly saturated, greenish-blue) ; green when hot /. Green Beads. Oxide of Copper ; blue when cold (greenish-blue if highly saturated). Sesquioxide of Iron contain- 'j The green color changes on cooling, accord* ing to the saturation, as well as the pro- portions in which the oxides are present, to light-green, blue, or yellow. not: Cold: ing Cobalt or Copper. Oxide of Copper containing Iron or Nickel. Sesquioxide of Chromium (yellowish-green) ; yellow to red while hot. WITH BORAX, IN THE EBDUCIM^Q FLAME, PRODUCE: a. Colorless Beads. Hot and cold: Silica, Alumina, Blnoxide of Tin. Baryta, Strontia, Lime, Magnesia, Glu- 1 oina,Yttria,Zirconia, Thoria; Oxides I When highly saturated become of Lanthanum and Cerium ; Tautalio f opaque by flaming. Aoid. J Oxide of Indium, Sesquioxide of Manganese. (With the latter the glass is liable to assume a feeble rose color on cooling.) Oxides of Silver. Zinc, Cadmium Lead, n ^ Nickel. Tellnrous J ^i^^^t blast, gray ) Bismuth, Antimony, Acid. Hot: Oxide of Copper ; on coal after complete reduction, otherwise the bead becomes opaque red. b. Yelloiv to Brown Beads. Hot: ' Niobic Aoid ; highly saturated. Titanic Acid (yellow to brown) ; when highly saturated, enamel-blue by flaming. Tungstio Acid (yellow to dark yellow) ; when cold, brownish. Molybdio Aoid (brown to almost black and opaque), ■ Vanadio Aoid (brownish); chrome-green when cold. c. Blue Beads. Hot : Protoxide of Cobalt ; the same when cold. Hot and cold: 84 plaitxer's blowpipe analysis. d. Green Beads. fSesquioxide of Iron (yellowish- or bottle-green; especially when cold; with tin on coal, copperas-green. Oxide of Uranium (yellowish-green) ; when highly saturated becomes black by flaming. Sesquioxlde of Chromium (light to dark emerald-green, according to the degree of saturation). Cold : Vanadic Acid ; brownish while hot. e. Gray and Qloudy Beads j the cloudiness frequently appearing distinctly during the blast. 1 Oxides of Silver, Zinc, Cadmium, Lead, )_,.,, , , ,, . ..»,.., /-I ij I T>- 11, . 1- ^T- 1 1 m 11 (With a short blast. (With a Cold : { Bismuth, Antimony, Nickel, Tellurous V , , , , , , I Acid jThallic Oxide. i longer blast, colorless.) /. Red Beads. {Sesquioxide of Didymium (rose-colored, if very highly saturated). Oxide of Copper (opaque), when highly saturated and imperfectly reduced. 2. Examination of the Substance with Salt of PHOSPHOBTrSb This test is likewise made partly on platiimm wire and partly on coal. The action of the S. Ph. has heen already explained, p. 47. The S. Ph. must be melted on the wire only gradually in small por- tions, since it boils violently while the water of crystallization and the ammonia are passing off, and if a snfBcient amount for a test were fused at once, it would seldom all remain on the wire. On coal the whole amount may be fused at once. The -points to be observed in testing substances with borax hold good for S. Ph. as well. Silicic acid being very slightly dissolved in S. Ph., the silicates can be very easily recognized by means of it ; the bases dissolve, while most of the silica separates and floats aboat in the fused glass in the form of a. gelatinous skeleton. Like the borax beads, those of salt of phosphorus can be made cloudy or opaque after dissolving certain substances. The colors produced in tlie S.' Ph. beads are generally different from those produced iu borax by the same substances, as may also be seen by comparing the following summary with the preceding table. EXAMINATION WITH SALT OF PHOSPHOUUS. 65 TABLE n. — The Metallic Oxides and Acids arranged with reference to the Colors which they impart to the Salt of Phosphorus Bead. WITH SALT OF PHOSPHORUS, IN THE OXIDIZING FLAME, PRODUCE: a. Colorless Beads. Siliea (very slightly soluble). Alumina, Binoxide of Tin (soluble with difBculty). Baryta, Strontia, Lime, Magnesia, Glu- 1 eina, Yttria, Zirconia, Thoria, Oxides i When highly saturated become opaque (white) by flaming. Hot and cold: of Lanthanum and Didymium, Tel- lurous Acid. Tantalic, Niobic, Hyponiobio, Titanic, and Tungstic Acids ; Oxides of Zinc, Cadmium, Indium, Lead, Bismuth, and Antimony ; Thallio Oxide. When not too highly saturated. (When highly saturated, yel- lowish to yellow ; and color- less on cooling.) h. Yellow Beads. Hot: Hot: Tantalic, Niobic, Titanic, and Tungstic j ,„, , . . , , . , . ^ . „ r^ ■ ■, err- /^j -—T.j (When highly saturated; but Acids: Oxides of Zinc, Cadmium, Lead, > , , ,. ' , , . 1. i colorless on cooling. Bismuth, and Antimony. 1 ° Oxide of Silver (yellowish) ; opalescent on cooling. . 1 When feebly saturated, colorless on cool- Sesquioxide of Iron, Sesqui- ( ;^g_ „ j^jg^y saturated, red while hot, oxide of Cerium. | and yellow when cold. Uranic Oxide ; yellowish-green when cold. Vanadic Acid (dark yellow) ; lighter when cold. Protoxide of Nickel ; reddish while hot. c. Red Beads. ( Sesquioxides of Cerium and Iron. If highly saturated, yellow on cooling. Hot: -I Protoxide of Nickel (reddish); yellow when cold. I Sesquioxide of Chromium (reddish);' emerald-green when cold. Cold : Sesquioxide of Manganese (light rose-color). d. Blue Beads. Hot : Protoxide of Cobalt ; the same on cooling. Cold : Oxide of Copper (greenish-blue if highly saturated) ; green while hot. e. Green Beads. Oxide of Copper ; blue when cold (greenish-bluo if highly saturated). Molybdic Acid (yellowish-green); lighter on cooling. Sesquioxide of Iron containing] The green color changes on cooling, ac- Cobalt or Copper; Oxide of 1 cording to the saturation, as well as Copper containing Iron or i' the proportions in which the oxides are Nickel. ' J present, to light-green, blue, or yellow. 1 Uranic Oxide (yellowish-green) ; yellow while hot. I Sesquioxide of Chromium (emerald-green) ; reddish while hot. Hot: Cold: 86 plattner's blowpipe analysis. WITH SALT OF PHOSPHORUS, IK EEDUCINQ FLAME, PEODUCB : a. Colorless Beads. Silica (very slightly soluble). Alumina, Binoxide of Tin (soluble with difficulty). Baryta, Strontia, Lime, Magnesia, Glucina, J When highly satorated, Yttria, Zirconia, Thoria, Oxide of Lan- v opaque (white) by flam- Hot and J thanum. ) ing. qq]^ . I Sesqnioxides of Cerium, Bidymium, Manganese. Tan talic Acid ; Oxides of Silver, Zinc, Cad- } . minm. Indium, Lead, Bismuth, and An- C ^^ ^""S Mowing. (Other- timony; TellurousAcid. ) wise gray.) Protoxide of Nickel (with tin on charcoal). h. Yellow to Bed Beads. Hot: Sesquloxide of Iron (yellow to red) ; on cooling, at first greenish, then smoke-gray to smoke-brown. Titanic Acid (yellow): violet on coolini,'. Niobic Acid (yellow). Tanadic Acid (brownish) ; when cold, green. Titanic Acid containing Iron. I (Yellow); when cold, brownish-red (blood- Tungstic " " " f red). Xiobie " " " (Brownish-red); when cold, dark-yellow. c. Violet Beads (amethyst-colored). Cold : J Sesquloxide of Didyminm (in transmitted light, after long blowing). I Titanic Acid (evju whon moderately saturated) ; yellow while hot. d. Blue Beads Cold: J Protoxide of Cobalt. I Tungstio Acid. e. Green Beads. r Oxide of Uranium ; less fine while hot. „ . , I Jlolybdio Acid ; dirty-green while hot. I Vanadic Acid ; brownish while hot. I Sesquloxide of Chromium ; reddish while hot. /. Gray and Cloudy Beads; the cloudiness frequently appearing distinctly during the blast. {Oxides of Silver, Zinc, Cadmium, Indium, i Most readily on coal and Lead, Bismuth, Antimony, Nickel ; Tel- > with tin. Colorless after lurous Acid ; Thallic Oxide. ' prolonged blowing. g. Red Beads. Cold : Oxide of Copper (opaque), when highly saturated, or with tin on charcoal. EXAMINATION WITH GLASS FLUXE3. 87 X QQ ci '^ S C3 o 01 ■^ ,a '$■ ^ ? ,i3 t-t o o '"o ^ o "oj -i^ _C1 g- •^ 0) .°° T3 'S O -2 s o C3 a> t-, c3 ^ ^ ■» >-; ^ C8 -S t^ 'S 0! 01 CD Ph ft CQ p< CQ QQ 0) (U ■^3 ,=5 -M « O -§ ^ r^ o -t= g T3 O «M O o 00 ^ n a> o T3 -4^ a P C3 ho s a 1 -^ -»j 00 (U OQ >. 'O ■& a> J= ^ CQ cS ^ -^ ^ o bc-^ ^a a, m 'S O J '* f^ .. 2 "" '^ ^^ o a> ^1 &^ C8 O CO IB ro ^ 03 S ,j:3 o T3 fi o ta A £ d 9 o n ^ kl fl h o 5 S T M 3 ft: 2 il £ S 8 t 1 2 S •a 5 T) 2 0} o SS CQ ^ a £ d P 13 << H 02 a o m 3 i g. 1^ ■2 o '© "3 o T" i" J. J> O CD O O o o o o ^H O w o 2^ ^ ?. C3 O 2 a o o m O C5 61) ^ a> o t> ■9 & £ "3 2 2 a a o CO o ^^S o =Sfn^ ,a §al 03 © frt 1 a" 2 ? tlr o 3 o 1 us net- -bro 1 ■sl ill i 3 3 X >H IH >H S CQ Ph P^ a 3 . 9 a X CO "S. M O [3 a 3 d k a 3 a s A O o o o a K 88 PLATTXEU'd BLOWPIPE ANALYSIS. 3. EXAMIXATIOX OF SCBSTAXCE WITH CaEBOKATB OF SODA. The soda is employed, either simply to fuse the substance together with it, or to effect the reduction of metallic oxides present, which latter result can generally be more perfectly accomplished with its- aid than by the reducing flame alone. w. The fusibility of the substance with soda. A large number of bodies combine with soda at a high tempera- ture, some yielding fusible, and some yielding infusible compounds. There are only a few which yield fusible compounds; they are chiefly: — silicic, titanic, tungstic, molybdic, tantalic, vanadic, ana niobic acids. When fused on charcoal, silicic and titanic acids unite with soda, effervescing and yielding a clear bead. When there is no excess of soda, the silicate remains clear on cooling, but the titanate becomes crystalline and opaque. Tungstic and the other acids likewise unite with soda with effervescence, but the compound sinks into the coal. Baryta and strontia salts likewise give fusible compounds with soda, and these also sink into the coal, while most lime salts, although fusing with the soda, are decomposed, even when their acids are more powerful than carbonic acid, and the soda salt sinks into the coal, leaving the lime behind. The powdered substance to be tested is mixed with the soda in the left hand, and the moistened mixture, spread in a shallow cavity on coal, is heated at first gently to drive off all the water, and then as strongly as possible. It is generally advisable to add the soda in small portions, so as to note clearly the changes produced, by adding constantly increasing amounts, which are spread moist upon the fused mass. Many silicates which are themselves fusible with difli- culty, while their bases are infusible, melt with a little soda to a clear glass ; but with more soda they form a slag-like or infusible mass When the assay is not soluble in soda, but is decomposed by it, it may be seen to gradually swell and alter in appearance, while it does not fuse to a bead with the soda in whatever proportion it is added. When the substance is neither dissolved nor decomposed by soda, the latter sinks into the coal and leaves the assay unaltered. An assay soluble in soda and free from coloring oxides, but con- taining sulphuric acid or sulphur, yields a glass which on cooling is yellow, or red to yellowish-brown, from the formation of sulphide of sodium, according as there was little or much sulphur present. The spread out mass obtained by fusing sulphates on coal with soda gen- erally has the same color, and when the mass, which has partially or wholly sunk into the coal, is cut out, laid on silver foil, and moist- EXAMINATION WITH CAKBON-ATE OF SODA. 89 ened thoroughly with water, it forms a,- black or dark-brown spot of sulphide of silver. This reaction is frequently used in testing a substance for sulphuric acid, or for sulphur in general.* Substances containing manganese, even in very trifling quantity, when powdered and fused with soda on platinum foil in the 0. F., especially with a little potassium nitrate also, yield manganate of soda, which spreads over the foil, and assumes a bluish-green color on cooling. When the examination of the substance by itself has caused the presence of salts of ammonia or mercury to be suspected, some of it is powdered, 'mixed with previously-dried soda, and ^heated in a. matrass over the spirit-lamp ; the salts are decomposed, and in the former case carbonate of ammonia, recognized by the smell and by red litmus paper, is liberated, while in the latter case the mercury collects in drops or forms a gray film. When silicates are fused with soda, they yield silicic acid to it, and easily fusible silicates are formed, containing a low proportion of silica. Upon adding more soda, the weaker bases are separated, and the mass becomes infusible. When the oxygen of the silicic acid is at least double that of the base, the addition of jus( the right amount of soda forms a clear glass, which remains clear on cooling, provided the resulting double silicate is fusible. When, however, the oxygen of the acid is just equal to that of the base, the assay is indeed generally decomposed by soda with efifervescence, but cannot be fused to a clear glass, because the resulting double silicate is too infusible. As before remarked, fusible silicates of infusible bases yield with a little soda a clear glass ; with more, an opaque glass ; and with still more, arc infusible, because their bases are separated by the soda. /3. Reduction of metallic oxides with carbonate of soda. Many oxides can be reduced on coal in the E. F. without ^da, but when mixed or combined with non-reducible bodies it is not only difficult, but sometimes quite impossible so to reduce them that their presence may be at once ascertained; by the addition of soda this can, however, be very perfectly accomplished. There are also metallic oxides which can be reduced perfectly with soda, but not without it The easy reduction efifected by soda is to be ascribed as well to the formation in the K. F. of cyanide of sodium, which absorbs oxygen with great eagerness to form cyanate of soda, as also, without doubt, to the fact that at a sufficiently high temperature the salt sinks into, the coal, while its carbonic acid and part of its oxygen are converted * It should be remembered, when using gas flames, that any sulphur compounds, in the gas may cause the same reaction with the silver ; selenium and tellurium also give a quite similar reaction. 90 plattuek's blowpipe axaltsis. by the charcoal into carbonic oxide, which, in connection with the gaseous sodium that escapes, exerts a reducing action on the metallic oxides. The best way to perform this reduction is to mix the pulverized assay with moistened soda in the left hand, spread the paste on coal, and treat it with a good E. F. for not too short a time. It is some- times difiBcult at-once to recognize the separated metal, and then the whole of the coal which is permeated with the soda at the spot where the reduction was effected, must be cut out, triturated with water in the mortar, and the coal, etc., washed away carefully until only metallic particles remain. When even a trifling amount of a re- ducible oxide was present, there will be small, flattened, lustrous metallic scales at the bottom of the mortar, or, in case the metal was difficultly fusible, and not soft, a metallic powder. This residue Bhould be examined with the glass, and under water with the mag- net, and il necessary, also tested on coal with borax and S. Ph., in case a mixture of several metals was obtained. In order to transfer the fine particles of metal to the coal, for the purpose of examination, they are wiped from the mortar with a bit ■of filter paper, which is then rolled up and burned on the coal. If there is a very trifling quantity of metal, the borax or salt of phos- phorus necessary for the examination is wrapped in the paper at the same time. When there are several reducible oxides present, they are generally obtained as an alloy. A little borax should be added to the soda when treating tantalates and slags, to reduce the trifling amomit of oxide of tin which is often present. The com- pounds of tantalic or silicic acid are more easily dissolved by .adding borax, which also prevents the reduction of iron that would other- wise alloy with the tin. The metals reducible as above with soda are, besides the noble metals : molybde- num, tnngsten, antimony, tellurium, copper, bismuth, tin, lead, zinc, indium, cadmium, nickel, cobalt, and iron.* Arsenic and quicksilver are reduced, but volatilize immedi- ately, and can only be obtained in the metallic state in the glass tube or matrass. If the assay contained arsenate of nickel or cobalt, a quite fusible button is always.ob- tained, which is rendered brittle by the considerable amount of arsenic in it. When, in addition to oxide of copper, there is an oxide of antimony or tin present, an eadly thsible, but brittle, alloy of copper and antimony or tin is obtained. Xeutral oxalate of potassa, or cyanide of potassium, may with advantage be substituted for soda when treating oxides of difficult * Antimony, tellurium, bismuth, lead, zine, indium and cadmium volatilize partly or entirely, unless reduced to alloys with other non-volatile metals, and yield coats of their oxides. EXAMIXATIOX WITH COBALT SOLUTION. 91 redueibillty, as they have a much greater reducing power. Even a feeble E. F. suffices to reduce oxides of tin, iron, cobalt, etc., imme- diately with these reagents, while soda would require a long-con- tinued and strong blast. The cyanide, however, has the disadvan- tage of spreading out over the coal at once, and thus scattering the reduced metal; while the oxalate, although also easily fused, spreads less, and the metallic particles can be more readily collected to larger buttons. Both of these reducing fluxes arc also preferable to soda when the reduction must be performed in a matrass, as for detecting a trifling amount of arsenic, the special directions for which will be given under the examination for arsenic. 4. Examination of Substances with Cobalt Solution. This test can only be employed for substances which have a nearly or quite white color after ignition in the 0. F. If the substance is not very dense, and will absorb the solution, a fragment of it is moistened with the solution, and gradually ignited quite strongly with the 0. P., being held in the forceps. Friable substances are mixed with the solution and spread on coal. In testing coats, a few drops of the solution are put on the coat, and it is then cautiously ignited, so as not to blow away the thin layer of oxide.* Crystalline substances, and such as are too dense to absorb the solution, must be pulverized, mixed with a little water, spread on coal, and dried. The crust is then moistened with cobalt solution, and gradually heated to a feeble glow in the 0. F. If coherent, the crust may be removed from the coal and held in the forceps. The color imparted to the assay must always be examined by daylight and when the assay is quite cool. The colors frequently seen when the substance is moist- ened with the solution, or on commencing to heat it, such as blue, red, black, proceed, it is true, from decomposition of the solution, but are by no means to be regarded as indications of substances sought. The quantity of solution required depends upon its concentration; a few experiments will show how much should be employed to secure * With very slight coats it is best to moisten tlie cool coat with cobalt solution and then direct the flame again on the original assay rather than on the coat itself ; the latter will gradually become sufficiently heated, add augmented by any fresh volatilization from the assay. 92 plattner's blowpipe analysis. a distinct reaction. A very dilute solution always yields the best results, as a too concentrated one is liable to turn the ignited assay gray or black. The following colors are assumed by some earths and metallic oxides and acids on being moistened with cobalt solution and ig- nited : «. Brownish-red, baryta; I. Flesh-color, magnesia, tantalic acid (when quite cold); c. Violet, zirconia (dirty-violet), phosphate, borate and arsenate of magnesia (fuse at the same time). d. Blue, alumina, silica; • e. Green, oxide of zinc (yellowish-green), of tin (bluish-green), titanic acid (yellowish-green), antimonic acid (dirty blu- ish-green). /. Gray, strontia, lime, glucina (bluish-gray), niobic acid. Only a few of these colorations are of use in recognizing bodies, ■especially those of alumina, magnesia, zinc, and tin. The blue of alumina must not be confounded with the blue produced by many silicates, which is due to silicate of cobalt This almost always appears fused on careful examination, while the blue of alumina is dull ; the former also only appears with a high temperature, and it is therefore well, if the substance after ignition with the solution shows no blue color, not to heat it too much, so as to fuse it. On the other hand, in testing for magnesia, the ignited substance may have assumed only a very feeble rose-color, and it can then be more strongly treated, even to fusion, if possible, since the red color will not only remain, but also become more distinct if magnesia is present The alumina and magnesia reactions are prevented by the pres- ence of cdlored metallic oxides, which generally produce a gray oi black mass, unless present in too small quantity. The methods of using the other qualitative reagents will be de- scribed under the special examinations. GENERAL EULES FOK QUALITATIVE EXAMINATIONS. 93 B. G-eneral rules for qualitative blowpipe examinations, by -which the separate constituents of compound sub- stances can be detected with the partial aid of the wet process. In the examination of compound substances with the aid of the blowpipe the wet process is frequently indispensable when all of the ingredients are to be detected, but even then the blowpipe is advan- tageously used, not only in carrying out various necessary operations, but also as a means of controlling the results and further examining the isolated constituents. Before proceeding to decompose the substance by the wet way, its behavior before the blowpipe should be ascertained, and from this the nature of tlje compound inferred; whether it is a salt of the alkalies, earths, or heavy metals, or a silicate, and whether the com- pounds contain easily reducible metallic oxides; further, whether it is a combination of metallic oxides, or o* sulphides or selenides, or of various metals with one another, in which latter division the metallic arsenides and tellurides are also to be placed. The further examination is essentially facilitated by knowing under what class of compounds the unknown substance belongs. When the compounds are insoluble in water, the most usual sol- vent is hydrochloric acid, and if solution does not take place at the usual temperature, the glass is heated over the spirit-lamp. Effer- ■(■escence indicates either the presence of a cai'bonate, when, the car^ bonic acid gas escapes without any odor ; or of a metallic oxide at a high stage of oxidation, and then chlorine gas escapes and is recog- nized by its pungent odor. The latter phenomenon occurs, for example, when' the mineral contains sesquioxide or binoxide of man- ganese, which are transformed into protochloride. The solution is then diluted with distilled water and examined for the various earths and acids, as will be directed under the separate examinations. The testing of silicates with hydrochloric acid is of especial im portance. Quite a number are wholly decomposed by it, the bases dissolving, while the silicic acid separates either in a gelatinous or pulverulent (and then usually rather voluminous) state.* * To determine wheiher silicates and other combinations of the earths and metalli* jxides are decomposed by acids, the fine powder is boiled for some time with the acid, and a portion of the fluid tested with ammonia and phosphate of soda. If a consider- able precipitate is formed decomposition has taken place, but if only a few flocks an thruv.-n down the substance is either not decomposed, or only with difficulty. 94 plattner's blowpipe analysis; When the silicate is entirely decomposable, the wliole is diluted with water, filtered, and the filtrate examined, as will be directed under the examination of silicates, for the various earths. Should it uot be wholly decomposed, another small portion must be decom- posed by fusion with carbonate of soda and borax, as will be described directly. In certain cases it is necessary to fuse a substance with nitre when examining it for a single ingredient, which is thus more highly oxidized and combined as an acid with the potassa of the nitre, from which it can be more readily separated and then recognized. Some- times, also, it is necessary to fuse a substance with bisulphate of potassa, and to dissolve the fused mass in water, in order either to free it at once from certain constituents, or to convert the whole into sulphates, and then proceed with the separation of the different constituents after solution in water. Decomposition of the substances by fusion with soda and borax, and treatment of the fused mass with hydrochloric acid. Seventy-five to one hundred milligr. of the very finely powdered substance being mingled with soda and borax * in the agate mortar, the whole is wrapped in a soda-paper cylinder, made of fine filter paper, and fused before the blowpipe in a cylindrical hole on char- coal, or in a charcoal crucible. The quantity of flux depends on the fusibility of the substance. Generally, one part by weight of soda and one of borax sufiBces : but the borax must be increased up to two parts when the substance contains much magnesia, alumina, glucina, or zirconia, while a considerable amount of barite requires an increase of both borax and soda. The 0. F. may be employed if the substance has been found free from easily reducible oxides, but otherwise, as in the case of certain slags, the E. F. must be used, so as to reduce and separate these oxides in the metallic state. Usually the quantity of reducible oxides is so small that they can- not easily be reduced to a single button, and then about sixty to eighty milligr. of silver, or, still better, gold, should be added in the form of a button and the charge treated with the E. F., just as directed for the charge in the quantitative copper assay, p. 302. During this operation the earthy constituents and the difficultly reducible oxides dissolve in the glass which is formed by the boras * The boracic acid being combined with the soda, exercises no injnrions effect during the eub8«qaent decomposition of the fiised compound by the wet process. GBNEKAL RULES J'OK QUALITATIVE EXAMINATIONS. 95 and soda, and melt to an easily fusible bead. The aoids of arsenic and the easily reducible oxides are reduced, while, in presence of sulphuric acid, there is a partial formation of sulphide of sodium, and part of the sulphur combines with the reduced metals. Tne reduced arsenic is partly taken up by these metals and partly voia- tilized, while the non-volatile reduced metals unite together and me^t with the silver or gold to an easily fusible globule, which goes to one side of the glass. The oxides of the metals that remain dissolved in the glass are present in the lowest stage of oxidation. Such a fusion, whether with the 0. F. or K. F., must be accom- plished with an active flame and with proper patience, since other- wise no thorough decomposition of the substance can be effected. The fused glass must be quite fluid, as clear as possible, and free from bubbles and metallic particles. If the glass continues to froth or show bubbles after long blowing, this is a sign that either the solution of the non-reducible portions, or the reduction of the reducible oxides, is not completed, and the fusion must be continued with a lively flame. An assay which has been fused in the 0. F. is taken from the coal when it has solidified, and after cleaning it from any adherent coal with the knife and brush, is first broken up in the steel mortar, or between paper on the anvil, and then pulverized in the agate mortar. It must be entirely reduced to powder, otherwise portions of the glass are apt to remain undissolved in the subsequent treatment with acids, and it must be pulverized iminediately, or else the fused glass will absorb moisture readily from the air, becoming tough and difficult to pulverize. When the assay has been fused in the E. F. and a metallic button reduced from it, or when it is presumed that the silver or gold added has been melted to a globule with the reduced metals, the assay must still be kept in a quite fluid state by means of a good E. F., and made to flow slowly from one point of the coal to another, until it is certain that the glass is quite free from globules of metal and bub- bles, while the metal is united to one globule beside it. After satis- factorily accomplishing this the blast is stopped and the assay set aside until quite cold, when it is removed with the forceps, the metallic button separated from the glass in the steel mortar, or between paper on the anvil, and the glass pulverized after cleansing it from any adherent coal. When the E. F. has not been pure or strong enough, part of the reducible oxides may remain and exert an injurious influence upon the further decomposition of the fused glass. 96 plattkee's blowpipe axaltsis. The oxides wHch can be easily reduced by the foregoing treat- ment, and thus separated from the earths and non-redncible oxides, are : the acids of arsenic, antimony and tellurium, and the oxides of silver, mercury, copper, bismuth, thallium, lead, tin, zinc, indium, cadmium, and nickel. Osmium, gold, platinum, iridium, rhodium, and palladium only occur in nature in the metallic state, and can therefore readily be separated from the non-reducible oxides and earths by the addition of silver or gold. The volatile metals either escape entirely in fumes during the fusion, or only in part, some of them coating the coal, while those that remam unite with the added silver or gold. The manner of conducting the farther examination of the reduced metals may be inferred from the remarks upon alloys in the detailed examinations which follow. The oxides of the heavy metals which cannot be reduced by fusion in the E. F. with soda and borax, are : the oxides of chromium, ura- nium, cobalt (in the absence of arsenic acid, or when the cobalt is not present in too great quantity), iron, manganese, and cerium ; and the following acids: raolybdic, tungstic, tantalic, niobic, vanadic, and titanic. The above oxides can, however, be readily separated again from the earths, for the most part, and recognized before the blowpipe, as directed in the various qualitative examinations. After finely pulverizing the fused glass, it is moistened with an abundance of water in a porcelain dish. Fig. 63, and then as much hydrochloric acid is added as will dissolve all of the powder and leave some free acid. The dish is placed upon the evaporating ring, Fig. T, over the lamp flame, and the powder stirred with a slender glass rod, until the soluble portions have been separated from the insolu- ble. The presence of sulphide of sodium, always formed if the substance contains sulphuric acid or sulphur, causes evolution of sulphuretted hydrogen ; the other constituents, excepting silica, are converted into chlorides and dissolved by the dilute acids. Occasion- ally almost all of the siUca also goes into solution. Since usually only combinations of silicic acid are decomposed by fusion with soda 4nd borax, it rarely happens that molybdic, tungstic, tantalic, niobic, vanadic, and titanic acids are here met with. After effecting the solution, the whole is evaporated to dryness, and this should be done where the vapors may not escape into the laboratory, in case too much free acid is present. The evaporation should be con- ducted gradually, especially toward the end, and carried to dryness, so as to remove the excess of acid and to render compact the silica, which separates in a gelatinous state during the process. When the solution has been evaporated to dryness, so that only the GENERAL RULES FOE QUALITATIVE EXAMINATIONS. 9? slightest possible odor of escaping acid vapor can be perceiTed, the mass is moistened with hydrochloric acid, and after some time is covered with distilled water. Then the dish is set over the lamp flame, in order to dissolve the chlorides and separate them from the insoluble portion, which in substances decomposed in this way gen- erally consists of silica alone. The silica can be very readily separated from the solution by filtration and washing with water, after which it may, if necessary, be tested B. B. with soda, Sesquioxide of iron is reduced during the fusion -to protoxide, and is not perfectly restored to the state of sesquioxide during the treat- ment with hydrochloric acid, and least perfectly when there is very much iron present. This being, however, essential to the certain •detection of the separate ingredients, the filtrate from the silica, with the first portions of the wash water, must be boiled in a test tube, -with a few drops of nitric acid, so as to convert the protoxide of iron into sesquioxide. The nitric acid necessary for the peroxidation of the iron may be added at once, before the evaporation, when it is not •desirable to have regard to the formation of sulphuretted hydrogen, which may ensue on treating the fused' assay with hydrochloric acid. The bases contained in the filtrate from the silica are separated by methods that will be given under the detailed qualitative examina- tions for different earths. Fusion of substances with nitre or iisulphate of potassa. This fusion is sometimes performed simply in the loop of a plat- inum wire, but oftener in the platinum spoon.* Powdered and friable substances are at once mixed in a finely pulverized state with the necessary amount of nitre in the agate mortar ; metallic com- pounds and alloys which cannot be powdered should be divided as finely as possible by hammering or filing. The quantity of nitre de- pends upon the character of the substance to be oxidized ; ordinarily three to four volumes are employed, unless the substance has a very high specific gravity. When but one ingredient is sought for, the fusion may be performed on platinum wire, after mixing the whole into a paste with water. A portion is smeared in the loop and fused in the 0. F. until it ceases to foam, when a fresh portion is smeared on and fused, continuing the operation until the volume of the fused mass is so great that it would no longer adhere to the wire. The * The nitre oxidizes the sniftice of the platiniini, it Is tme, bnt so slightly that iti ^ects on the spoon need not be feared. 98 plattitee's blowpipe analysis. wire should be kept in an inclined position, with the loop turned downward, as the nitre has a tendency to flow down the wire. When it is suspected that the substance contains an extremely small amount of the body sought for, or whea it is designed to oxid- ize Beyeral ingredients, in order to treat them further in that state, or if an alloy which cannot be powdered is under treatment, a some- what larger quantity must be used, and the fusion performed in the platinum spoon. The whole mixture should not, however, be poured into the spoon at once, but at first only small portions, since gases and Tapers escape during the fusion, and may easily cause the melt- ing mass to run over. At first the bottom of the spoon is heated with the 0. P., which is then directed into the spoon, and the whole fused until it becomes quiet. The remainder of the mixture is then added in similar portions, and fused after each addition until it ceases to froth strongly. The position of the spoon should mean- while be altered, so that every part of the mixture may be reached by the flame, and the spoon always appear red hot. Only those alloys can be fused with nitre in the spoon which oxidize readily, and do not combine with the platinum at the tem- perature which can be produced by the blowpipe. The fusion of such compounds with nitre is properly limited to the detection of very trifling quantities of arsenic in metals from which it can only be separated with difficulty, and which are very infusible, e.g., nickel and cobalt The fusion of substances with bisulphate of potassa is always effected in the larger platinum spoon, in the same way as with nitre, and most suitably over the spirit-lamp. The substance must be per- fectly dried, previously reduced to flne powder, and elutriated, if decomposed with difficulty. If melted by the blowpipe flame the too btrong heat is very liable to partially expel the sulphuric acid from some of the sulphates formed by the fusion ; but if the spirit flame is employed, and the spoon at first only kept dii-ectly over the tip of the flame, until most of the gases have escaped, and then held deeper in it, the heat acts equally upon the bottom of the spoon all around, the fusing mass is only brought to low redness, and the resulting salts are not destroyed.* When much of the bisulphate must be used, the spoon frequently becomes filled before all of the mixture has been charged, and then * It is adrantageons in these foraons to snrronnd the flame with a sheet-iron cylinder, leaching about to the top of the flame, and which rests on the glass lamp, haring •everal openings at its lower end. GENEKAL KULES FOR QUALITATIVE EXAMINATIOJS'S. 99 the fluid mass must be poured out upon the anvil, and the remaindei of the mixture fused. It is, indeed, always advisable to pour out the mass, as it can then be readily pulverized in the steel mortar when cold, and thus more quickly dissolved in water. The quantity of bisulphate of potassa depends upon the various constituents of the substance to be fused ; thus, for protoxide of iron 3.6 parts by weight of bisulphate are required to convert it into sulphate ; for lime, 4.5 ; for magnesia, 6; for alumina, 7.8. It is always more prudent to employ rather more of the acid salt than is exactly required, since alumina and the oxides of iron are liable to lose a part of their com- bined sulphuric acid at a long continued high temperature. The firm mass resulting from the fusion of a substance with nitre or bisulphate of potassa, whether on platinum wire or in the spoon, when not poured out cannot well be pulverized and thus dissolved in water, because the platinum may easily be injured in detaching it. It is therefore necessary to lay the wire or spoon with the fused mass in a porcelain dish of suitable capacity, pour over it the amount of water necessary for solution, and set the vessel upon the evaporatiug ring over the lamp. As the water becomes hot the mass generally separates from the platinum and can be crushed with the pestle of the agate mortar. In most cases the water may be heated to boiling and the salt thus readily dissolved ; but when a substance containing titanic acid has been fused with bisulphate of potassa, in order to make the titanic acid soluble, and the fused mass has been covered with more water than was exactly required for its solution, the latter must not' be boiled, or else the titanic acid will be imperfectly dis- solved, and Jhat which had been dissolved at a lower temperature will be thrown down again. These operations in the wet way afford residues and precipitates, which after filtration are to be further examined and must therefore generally be dried. When there is enough of the mass the filter is spread open upon a double layer of blotting paper, the mass scraped off with a spatula, transferred to a porcelain dish, and dried over the lamp. When there is but little of it, the folded filter is held up to the light, the empty portion cut away with the scissors, and the remainder, with the adhering mass, dried immediately in the dish over the lamp. The dry paper is then doubled together, hung upon a platinum wire, ignited at one end, and burned over a clean porce- lain dish, which receives the residue, mingled with a little coal. These coaly particles may be very easily burned away in the plati- num spoon, but this is not necessary when the dry mass is to be .further treated with fluxes, as they are thereby consumed. 100 PLATTNEE'S BLOWni'E ANALYSIS. The chemical operations ordinarily performed in making examin- ations in the wet way, such as precipitating, decanting, filtering, washing, etc., need not be further mentioned here, since probably ■ every one who engages in blowpipe analysis will have some knowl- edge of them, or the requisite information can be obtained from any manual of chemical analysis. II. Qualitative examination of Minerals, Ores,, and Metallurgical -products Jjefore the blow- pipe for metallic and non-metallic elements. In this division the description of each examination is preceded — 1. By the enumeration of all the minerals and metallurgical pro- ducts in which, the substance sought for constitutes an essential ingredient. 2. In case of the silicates, which are less easily distinguished from one another than the other oxidized minerals, their behavior alone before the blowpipe, with regard to their relative fusibility, is indi- cated immediately after the name of the mineral, by means of the numbers I, II, III, and the letter A, because this facilitates the com- parison of the mineral in question with minerals already determined. I denotes that the silicate fuses readily to a bead ; I — II " " it fuses with diflBculty to a bead; II " " it can be easily fused on the edges ; II — ^III " " it fuses with difficulty on the edges ; III « « it is infusible; A " bubbling, intumescence, frothing, and ramifica- tion. 3. The behavior, so fkr as known, of salts insoluble in water, silicates, aluminates, and combinations of metallic oxides, in a powdered state, with hydrochloric acid, is indicated by the following symbols — 1 denotes that the mineral is perfectly dissolved or decomposed by hydrochloric acid ; IG " that in case of silicates the silica separates in a gelat- inous state ; 1 — 2 " that the mineral is decomposed or dissolved entirely, but with difficulty; 2 " that it is imperfectly dissolved or decomposed; 3 " that it is insoluble or undecomposable in the acid. GENERAL RULES FOR QUALITATIVE EXAMINATIONS. 101 4. To afferd a better survey of the composition of the minerals, the chemical formula is annexed to each, and, with few exceptions, where first mentioned.* 5. In the case of minerals which are of especial interest to the miner and smelter on account of the metal in them, the percentage of the metallic ingredients is given, so that the proportion of metal found by the blowpipe in any mineral under examination may be readily compared with that of some known mineral. A. Examinations for Alkalies and Earths. 1. POTASSA, K'O. Its occurrence in the mineral kingdom. Potassa is chiefly found in combination with chlorine and sul- phuric, nitric, and silicic acids. a. With chlorine in — Sylvite— KCl; Carnallite— KMgCr+6H'0. Kainite— KCl+MgS0'+3H'0. b. With sulphuric acid in — • Aphthitalite (fflaserite)—K'80\ Alunite 2,— WO, 3AP0", 4SO'+6H''0, usually mixed with some SiO', Na^SO', CaSO', and BaSO*. Kalinite {potash ahim)—WO, AFO', 4SO'+24H"0. Syngenite-K=0, CaO, 2S0'+H=0. Polyhalite— K»0, MgO, 2CaO, 4SO'+2H'0. 6elbeisenerz—S.'0, 4Fe=0», 5SOs+9H»0. Jarosite— K"0, 5Fe''0^ 6SO"+7H»0. c. With nitric acid in — ;Nitre — KNO', almost always mixed with othersalts, e.g., CaSO', KCl. d. With silicic acid in — a. Anhydrous silicates, or such as yield little water in the matrass; here belong: Kallophilite— K=0, AI'O', 2SiO», with little Na'O and CaO. * In enumerating silicates a^d other minerals of complicated composition the old formulas have been retaiue'*, since, as von Kobell says, they give a better in- sight into the chemical behavior and rew'-icns of the minerals. C. P. Eammelsljerg (Handbuch d. Minerdlchemie. Leipsic, 18"''^ treats best of the chemical nature of minerals. 102 plattneb's bloatpipk analysis. Leucite, III, 1 — K'O, APO', 4SiO', incl. more or less Na'O. Hyalophane, 3,— K'O, APO^ GSiO^+BaO, A1=0', 2SiO". Orthoclase, II, 3,— K'O, APO', 6SiO'; generally some K'O is re- placed by Na'O; BaO, CaO, MgO and Fe'O" are sometimes present. Varieties are: Adularia, ainazonstone, loxoclase, saii- idine. Microcline is a related, triclinic feldspar. Micas. [Their true composition is still uncertain. "Kammelsberg regards the micas as containing the three silicates E'SiO', E'SiO', E'SiO' in various molecular relations." Dana, System of Mineralogy, 6th ed., p. 612.] They contain essentially APO' and El'O(Na'O), to which are added in many varieties MgO and reO(MnO); sometimes part of the K'O is replaced by Li'O, and of the APO' by Fe'O'. CaO is present only in inconsiderable quantity. H'O and P are almost always present; H'O is chemically combined and only escapes on strong ignition. Muscovite {potash mica, sericite, in part), I-II, 3. Damourite (On- cosine) II A, 1 (by H'SO'). Kalieisenglimmer. Litliia mica (Lepidolite, Zinnwaldite), I A, 2. Magnesia mica and magnesia-iron mica (biotite, phlogopite), I-II, 3 (I with IPSO'). Baryta mica (Oellacherite in part). Certain micas contain TiO' (1-3 per cent.) and traces of Tl, Rb, Cs. Puchsite and Chromglimmer are potash (or magnesia) micas con- taining Cr'O'. Lepidomelane, I-II, 1, — a mica rich in Fe^'O'. y3. Hydrous silicates : Agalmatolite, II-III, 3 — silicate of potassa and alumina. Zeagonite, II, 1 G,— K'O, Al'O', 3SiO''+4H'0 ; contains also the corresponding potassa silicate. Gismondite is of similar composition. Apophyllite, I, A 1,— K'O, 8CaO, ]6SiO'+16H=0; contains F. PhiUipsit«, I A, 1 G, — silicate of lime and alumina containing potassa and soda. Finite, II, 2, SiO^ APO', K'O, FeO, Fe'0^ MgO, CaO, Na'O, H'O : of similar composition are gigantolite, liebenerite, gieseckite, iberite, killinite. Glauconite (griinerde) vide iron. There are several other minerals besides the above silicates which contain po- tassa, but for the most part in inconsiderable quantity, e.g. Albite, elaeolite, nephelite, vide soda. Stilbite, vide lime. Psilomelane, vide manganese. EXAMINATION FOR POTASSA. 103 Examination for Fotassa. In the easily fusible potassa salts, excepting phosphate and borate, and in the compounds of potassium with chlorine, bromine, etc., this alkali is at once recognized by fusing a small portion on a loop of platinum wire with the tip of the blue flame. In the complete absence of soda, and with a clean wire, the outer flame is colored more or less strongly violet, p. 74. Soda renders the flame more or less yellow, and lithia red, so that m their presence this simple test will not show the presence of potassa at all, or not with perfect certainty. Sometimes when the amount of soda or lithia is very trifling, the outer flame has so dis- tinct a violet color near the assay, that the reaction may be satisfac- tory; but if the soda amounts to a few per cent, even, this colora- tion becomes imperceptible. The simplest means of detecting potassa with certainty in salts in which, owing to a greater or less amount of soda, the violet colora- tion of the flame cannot be recognized, consists, according to Cart- mell, in viewing the color of the flame through deep blue cobalt :glass, or a stratum of indigo solution.* The presence of potassa is recognized, according to the thickness of the intervening medium, by the violet or poppy-red {ponceau-rothe) color, while a very large amount of soda produces a blue color, and a smaller quantity is not perceptible. The flame of a Bunsen burner, p. 9, Fig. 8, or the blue blow- pipe flame may be employed. In the latter case a small stand. Pig. 73, renders the observation more convenient. In the small tube, h, fastened in an iron or lead foot, the wire, s, is made to slide at pleas- ure, and it supports in a clamp the cobalt glass, g. A few experiments will determine the proper situation for the glass between the eye and the flame, and give practice in holding the platinum wire with the assay in the tip of the blue flame, which is not visible through the glass. For the indigo solution a small open vessel may be formed by means of glass strips and a suitable cement, and then also set upon a stand. If the assay contains substances which pro- duce a luminous flame, as in the separation of * The solution, which must bo filtered, contains in 1500 to 2000 parts water, 1 part indigo, previously dissolved in 8 parts fuming sulphuric acid. 104 plattnek's blowpipe analysis. carbon from 'buniing organic matter, these must first be removed by igniting the assay, since otherwise the same violet color will be per- ceived through the glass as that caused by potassa. The violet and red rays proceeding from the glowing wire must likewise not be con» founded with the proper potassa coloration, which rather extends out from the assay toward the tip of the flame.* Viewed through moderately thick cobalt glass, or a thin stratum of indigo solution, the lithia flame is carmine-red, but through very dark or thick glass, or a thicker stratum of solution, it ceases to be visible, while the red potassa flame is still distinctly seen, and, there- fore, when potassa is to be detected in presence of lithia, a thicker or darker glass must be used, the effect of which has been previously tested with pure salts. According to observations by Merz {Journal f. praTct. Ch. vol. 80, p. 491), the lithia flame is invisible through green glass, while the potassa and baryta flames appear bluish-green, and that of soda orange-yellow. In the case just mentioned, the thicker cobalt glass or indigo solution may therefore be replaced by green glass. The potassa in silicates cannot always be detected with certainty by the coloration of the flame, because these compounds nearly always contain more or less soda, which prevents the reaction ; but even in silicates containing little soda, the alteration' of the outer flame is generally so slight that it cannot be perceived at all, or only indistinctly. On the other hand, according to Bunsen, the cobalt glass and indigo solution may be advantageously used to detect potassa in silicates also, by heating such compounds with gypsum, free from potassa and soda, in the flame, thus forming silicates of lime and sulphate of the alkali, which is volatile and colors the flame. Here» too, regard must be had to the remarks before made, if lithia is present (vide also remarks under lithia). Cornwall, 1. c, recommends decomposition of silicates by heating on platinum wire with a mixture of two parts of gypsum and one part of fluor-spar, if they are not decomposable by acids. When not too trifling in its amount, potassa may also be with, certainty detected in silicates by the wet way. About one hundred milligr. of the very fine powder are fused, p. 94, with one hundred • Solution ot permanganate of potassa serves better than indigo solution, being far more transparent to the potassa-flame coloration. Cornwall, Amer. Cltemist, April, 1872. SODA. 105- imilligr. each of borax and soda (preyiously ascertained to be perfectly free from potassa) to a transparent globule, free from bubbles. Should the assay contain considerable lime or mag- nesia and appear very infusible, somewhat more borax is added.* ;The fused globule is dissolved with dilute hydi-ochloric acid in a porcelain dish, evaporated to dryness, dissolved in a very little water, diluted with alcohol (not enough, however, to precipitate any salts), and filtered, or when clear, decanted from the resi- due of silica into a small test tube, and the residue then washed with alcohol of 80°. If to the clear solution a few drops of a rather concentrated solution of bichloride of platinum are added, it will be at once seen whether potassa was present in the substance, and if so, whether in trifling or considerable quantity. When, for example, the volume of the double chlo- Kg.73. j.j^g jg known, which separates when one hundred milligr. of a feldspar, yielding by chemical analysis, say fourteen per cent, of potassa, are decomposed as above with soda and borax, an approxi- mate estimate may be made of the amount of potassa in other sili- cates, from the quantity of the double chloride formed. This may be done with most certainty by employing a test tube about ten millim. in diameter, drawn out below to a short tube two millim. in diameter, in which the crystalline chloride of potassium and plati- num can settle. Fig. 73.1 2. Soda, Na=0. ; Its occurrence in the mineral kingdom. Soda occurs quite frequently, but always in combination with other elements, being never found free. a. It occurs as chloride in Halite (common salt) — NaCl, generally containing trifling quan- tities of GaCP and MgOF. * The amount of potassa derived from the burnt portion of an ordinary piece of ohareoal is so exceedingly trifling that it could not be detected if the substance were free from potassa, and therefore exerts no Injurious Influence upon the assay. f The precipitate obtained by pl^tinic chloride may contain rubidium and cae- sium, which cannot be detected by the blowpipe alone. Of the three compounds caesium-platinum chloride is least soluble in water. Eb and Cs have been found in small quantity in lithia mica. Cs forms an essential part of the very rare min- eral poUuoite— CsO, A1»0', 5SiO'-|-H=0, with 30 per cent. Cs'O. In the matrass it yields very little water ; thin splinters fuse on the edge to a blebby enamel and color the flame reddish (from some soda). Hydrochloric acid decomposes P., com- pletely, separating SiO^. 106 plattnek's blowpipe analysis. I. Aa fluoride in Cryolite, 1-2,-6 Na F + Al' F'. Chiolite and chodneffite are similar. Paehnolit&— Na F + Ca F' + Ai F« + H" O. Amblygonite, vide lithia. Duranglte, vide alumina. Pyrochlore, vide lime.. c. With sulphuric acid in — Thenardite— Na' S 0*. Mirabilite— Na" S 0* + 10 H' 0, but often impure, Glauberite— Na> S O* + Ca 8 O*. Bloedite— Na^ S 0» + Mg 8 0« + 4 H» 0. Mendozite (soda alum)— Na" O, Al' 0>, 4 8 0» + 24 H" 0. Gelbeisenerz, natronhaltiges (jarosite, part) 1, — Na» 8 0' + (Fe")* 8* 0" + 9 H' 0. Svanbergite, II, 2, contains Al' 0=, Na' 0, Ca 0, Fe 0, 8 0', P' 0», H' O. d. With nitric acid in — Soda Nitre — Na N 0'; also small quantities of Na CI, Na^ S 0* and Ca S 0*. e. With carbonic acid in — Thermonatrite — Na' 0' ■\- W 0] also containing especially Na" S 0' and Na CI. Natron— Na" C 0° + 10 H" 0. Trona (urao)— 3 Na' 0' + H' C 0' + 3 H' 0, and sometimes some Na' S 0\ Gay-Lussite, 1,— Xa' C 0' + Ca C 0' + 5 H' 0. /. With loric acid in — Borax (tinkal)— Na' B* 0' + 10 H' 0. Ulexite— Na' B' 0' + Ca' B" 0" + 15 or 24 H' ; also small quantities of K' 0, S 0', CI. g. With silicic acid in — a. Anhydrous silicates, or such as yield only trifling quantities of water in the matrass : Nephelite II 1 G ) "^ ^^^' ^' ^" ^' ^ ^^' ^'' ^^ ^^ ^'' ^^^ *^«- Elaeolite,ili,l G; I ^"^^^^^ ^'""H ^"^"tities of Fe' 0', Ca 0, ; Mg 0. Albite (pericline), I-II, 3,— Na' 0, Al' 0', 6 Si 0'; with a little K' 0, Ca 0, Mg 0. Albite and anorthite {vide lime) molecules appear in iso- morphous mixtures, of which the most important are : Oligoclase, I, 2,— w[Na' 0, Al' 0', 6 Si 0'] + Ca 0, Al' 0', 2 Si 0'. SODA. 107 Andesite, I-II,— Na' 0, Al' 0', 6 Si 0' + Ca 0, AP 0', 2 Si 0'. Labradorite, I-II, 2,— w[Ca 0, Al' 0', 2 Si 0'] + Na' 0, Al' 0', 6 Si 0'. Saussurite, II, 3, similar to labradorite, contains a little water. Acmite, I, 2,— aiNa" 0, Si 0', + yFe 0, Si 0' + 3 Fe' 0', 3 Si 0', •with a little Mn 0. Similar are, segirite, arfvedsonite, riebeokite, orooidolite, I-II, and Glauoophane, I, 2 ; Al' 0= replacing Fe> O' ; Jadeite, II, 3,— aNa' 0, Si 0= + j/(Ca, Mg, Fe) 0, Si O' + z{M', Fe") 0', 3 Si 0» ; Mizzonite, I-II, 2, — a soapolite rich in soda ; vide lime. /3, Hydrous silicates : , Nartrolite (mesotype, in part; spreustein (bergmannite), I A, 1 G,— Na' 0, Al" 0', 3 Si 0^ + 3 H= 0; with Ca = brevicite, I-II. Analcite, I A, l,-~]Sra" 0, AP 0', 4 Si 0' + 2 H' 0. Peotolite, 1, 1,— H' 0, Na' O, 4 Ca 0, 6 Si O', excluding small quantities of Al' 0». Mesolite, isomorphous mixture of natrolite and scolecite. Faujasite, I A, 1, similar to mesolite, poorer in Al' O'. Paragonlte (soda mica), II-III, 3,— (H, Na)' O, Al' O', 2 Si 0', with K' 0, Fe' O'. Thomsonite, stilbite, epistilbite, vide lime. y. Silicates with sulphates (and chlorine) : Nosite, I, 1 G,— Na 01 + 4 (Na' 0, S 0') + 9 (Na' 0, Al' 0', 2 Si 0') with ^ of the isomorphous lime compound ; some Na' replaced by K' 0. Similar are haiiynite and lapis lazuli, as well as ittnerite (seolopsite), I A, 1 G. Lapis lazuli and ittnerite with hydrochloric acid evolve H' S, due to sodium sulphide. S. Silicates with carbonates : Canorinite, I A, 1 G,— 2 Ca 0, Si 0', + nl2 K' O, Si O' + 2 Al' 0\ 3 Si 0']. E' = Na' O and H' ; Si O' is partly replaced by C 0' ; davyne is similar. e. Silicates with admixture of niobates, zirconates and titanates/ Wohlerite, eudialyte, oatapleiite, vide ziroonia. Astrophyllite, mosandrite, vide titanium. C. Silicate with chloride : Sodalite, I-II, A, 1 G,— Na CI + 2 Na' O, Si 0' -u 2 Al' 0', 3 Si 0». 7j. Silicate with fluoride: Leucophanite, 1,-3 Na F + 4 B 0, 7 Si O' ; B O = Ca O, Be 0. Ueliphanite is similar. ^. Silicate with borate : TourmaUne, vide magnesia. There are various other silicates containing more or less soda, especially: Leueite, orthoolase, vide potassa; Spodumene, petalite, vide lithia ; Vesuvianite, xanthophyllite, soapoUte (wernerite), vide lime. 108 plattitbb'b blowpipe analysis. Examination for Soda. Soda may be very readily detected in the natural salts aboTC men- tioned, as well as in any salt of whicli it forms a constituent, by heating quite a small portion of the salt in the loop of a platinum wire, with the tip of the blue flame. The outer flame immediately becomes enlarged and assumes a reddish-yeUow tinge, p. 74 even when a large amount of potassa or lithia is likewise present. If the salt is free from phosphoric or boracic acid and contains a very large amount of potassa, the flame is not pure reddish-yellow close to the assay, but rather riolet, while at a greater distance the reddish-yellow color alone prevails, and thus it may be quite well determined whether there is much less soda than potassa present. In presence of lithia the yellow flame is more strongly mixed with red, in pro- portion as the salt is richer in lithia and poorer in soda, so that with considerable lithia and little soda the flame is not reddish-yellow, but yeilo wish-red. When a small quantity of any volatile salt of soda on platinum wire is brought within the zone of fusion of the gas-burner, p. 9, Fig. 8, the light proceeding from it renders a crystal of bichromate of potassa colorless, when held near the flame (Bunsen : Ann. d. Chem. w. Pharm. Bd. CXI. Hft. 3). A better reaction is obtained when this deep red salt is replaced by a slip of paper, about one centim. square, coated with iodide of mercury, which assumes a white color, with a shade of pale yellow. Potassa, lithia, and lime do not prevent this reaction. According to Merz the soda flame appears orange-yellow through green glass, while the potassa flame is bluish-green and the lithia flame invisible. In silicates, as weU in the natural silicates as in other more or less fusible compound substances, the presence of soda can also be de- tected by the reddish-yellow flame, when small splinters are heated in the platinum forceps. Bunsen's test, given above, is of especial interest in the examina- tion of silicates, but can only be performed with the aid of the gas- burner. It is necessary to have a number of feldspars, accurately analyzed and arranged according to their increasing proportions of soda ; these are ignited and kept in a pulverized state. If one of these and the specimen to be examined, with or without the addition of gypsum, are held in the zone of fusion at the same time, taking care that equal lengths of wire shall be heated, a strip of iodide of LITHIA. 109 mercury paper placed before the flame will be more or less blanched If now the specimen to be determined is withdrawn from the flame and the paper assumes a perceptibly redder shade, the specimen con- tains more soda than the silicate used for comparison, while if the paper becomes whiter, the contrary is the case. By determining in this way between what numbers the reaction occurs, the amount of soda in the mineral under examination can be approximately ascer- tained. Various precautions must be observed in this test, but foi these the reader is referred to the work cited above. 3 . LiTHiA, Li" 0. Its occurrence in the mineral kingdom. Lithia is never met with in the free state, but always in combina- tion with other bodies. a. In combination with phosphoric acid, partly with and partly without fluorine, in Amblygonite I, 3,-3 A? P'' 0' + 3 E F; K = Li and Na. Triphylite 1, 1, —Li' P 0' + Fe= P" 0". A part of the Fe is replaced by Mn and a little Mg 0, and a part of the Li' by Na' 0. In the very similar Tetraphylin there is somewhat more Mn and Li" 0. i. In silicates : Euoryptite— Li^ O, kV 0', 2 Si 0^ Spodumene, I A, 3,-3 Li' 0, AF 0', 4 Si 0'. A part of the Li' replaced by K' and Na' 0. Petalite, II, 3,-4 Li' 0, 3 AP 0% 20 Si 0'. Li' partly replaced by Na' 0. Castorite is similar. liithia tourmaline, vide magnesia. Xiithia mica, vide potassa. There are also some other minerals of which Uthia forma a subordinate part ; as : Durangite, vide alumina ; Lithiophorite, vide manganese. Examination for Lithia. Lithia is very readily detected in its salts by heating them, either on platinum wire or in the forceps, according to their fusibility, with the tip of the blue flame; a red tinge is always imparted to the outer flame, owing to the carmine-red color which lithia communi- cates. Many strontia and lime salts, however, likewise give a red flame, which fact must be borne in mind, and the salt in question :furthei: tested, as will be directed under strontia and lime. The 110 PliATTNER'S BLOWPIPE AKALTSIS. cannine-red produced by a pure lithia salt may appear quite different when other substances are present, which also color the flame, e. g., soda. Should the salt be free from soda, but contain phosphoric acid, which colors the flame bluish-green, the red and green do not unite, but both colors are separately visible. Triphylite shows this phenomenon, p. 74. A mixture of lithia and potassa salts upon a loop of platinum wire imparts to the flame a red tinge, which is less intense and more inclined to reddish-violet as the potassa increases in comparison with the lithia. A mixture of lithia, potassa, and soda salts in which lithia predominates, causes a yellowish-red flame, while if potassa predominates the flame is reddish-violet quite close to the assay, but reddish-yellow beyond. If the soda prevails and the assay is fusod with the tip of the blue flame, the reaction of the potassa and lithia is concealed ami only the reddish-yellow color is perceptible, but by touching the salt with the outer flame only, and employing a very gentle blast, a distinct red flame may be frequently produced for a short time. According to Stein {Ann. c. Chem. u. Pharm. von Wohler tu Liebig, vol. 52, p. 243), the lithia reaction is rendered indistinct and sometimes quite concealed by the soda because the temperature is too high. He has found that by fusing the assay on platinum wire, just so that it remains porous, and then soaking it in tallow and heating it in a candle flame, the red lithia flame is still distinctly visible, even when the amount of lithia is less than ^^sVir that of the soda. The effect of the lithia flame when viewed through cobalt glass or indigo solution has already been stated, p. 104, and this affords a certain means of detecting lithia when mixed with soda and potassa. Cartmell (L c.) recommends the observation, through indigo solution, of the flame produced in the Bunsen burner by all these bases together by the side of a pure potassa flame. According to Bunsen, the distinction succeeds still better by observing the successive alter' ations of the color which occur when each of the flames, produced side by side, is viewed through a stratum of indigo solution con- stantly increasing in thickness. For this purpose a prism of plate glass containing the solution is held before the eye. Pure carbonate of lithia, or chloride of lithium, shows a carmine-red flame through the thinnest stratum, while potassa still appears sky-blue to violet. The lithia flame grows feebler as the stratum increases in thickness, and disappears long before the thickest stratum comes before the eye Potassa and soda have no influence in this case. Since the two salts EXAMINATIOK FOR LITHIA. Ill just named give a more intense color than any other lithia com- pounds, it is only necessary to nark that point of the prism where the color imparted to the flame by these bodies becomes inyisible, and then through the strata above this mark only potassa can be per- . ceived, but lithia never. This portion of the prism then perfectly replaces a thick cobalt glass. If now a portion of a potassa salt containing lithia is fused in the flame (soda alters the event but little, unless present in quite a Jarge proportion), and the flame compared with a pure potassa flame pro- iuced opposite to it, the flame- containing lithia appears redder than the pure potassa flame, through thin strata; through somewhat thicker strata the flames are equally red, if the amount of litliia is very trifling in comparison with the potassa ; if the lithia predomi- nates, the intensity of the now red lithia flame decreases perceptibly as the thickness of the stratum increases, while the pure potassa flame is scarcely weakened at all. In silicates containing lithia this alkali may likewise be detected by the blowpipe flame. Unless there is too little lithia present it is at once recognized by the red flame produced by a small splinter heated in the forceps. In the absence of soda an intense purplish- red flame is produced while the assay is fusing ; this is the case with lepidolite and castorite. Less intense and pure, but still distinctly perceptible colorations are produced by petalite and spodumene, ■when not too strongly heated. Silicates containing only a little lithia, e,g.. lithia-tourmaline, and certain scapolites, color the flame only very indistinctly, or not at all red. In this case Turner's method may be employed, which consists in making a paste of the finely-powdered mineral with a mixture of one part fluor spar, one and a half bisulphate of potassa, and a little water, and fusing it on _a loop of platinum wire within the blue flame, at the same time carefully observing the color of the outer flame. According to Merlet, two parts of the mixture must be taken for one of the silicate to make the reaction for lithia perfectly sure. If the silicate contains a little lithia, this colors the flame red, but not very intensely, the red inclining strongly to the violet of the potassa. If the silicate is free from lithia, only the violet potassa flame ensues ; soda renders the reaction indistinct. If the silicate contains boracic acid, e. g., tourmaline, a green flame is at first pro- duced, showing the boracic acid, but afterward a more or less in- tense red flame is caused by the lithia. The mixture proposed by Poole serves still better than Turner's for detecting lithia. — It consists of two parts ignited gypsum and one part fluor spar. Dwgler's J. 191. Heftl. 112 plattitek's blowpipe analysis. Lithia may also be detected witli certainty in silicates by using a Bunsen burner and the indigo prism. The assay powder is heated with gypsum in the zone of fusion, and opposite to it some carbon- ate of potassa, while both flames are observed through the prism, which is passed before the eye. 4. Ammonia, N" H'. Its occurrence in the mineral Tcingdom. Ammonia is always found combined with other bodies. a. As ammonium with chlorine in Sal ammoniac, — N H^ CI. l. With sulphuric acid in Mascagnite,— (X H*)» S 0*. Tschermigite (ammonia alum),— (N H*)" 0, AP 0% 4 S 0' + 34 H' 0. c. With boracic ffcid in Larderellite,— (N H*)' 0, 4 B' 0' + 4 H= 0. Examination for Ammonia. In the compounds of ammonia, many of which can be recognized at once by their volatility in the matrass, p. 61, the ammonia may be very easily detected by mixing a little of the substance with soda and gradually heating them in a matrass or closed tube over the spirit-lamp. An ammoniacal odor is evolved, and a bit of moistened red litmus paper inserted in the tube is colored blue. White clouds also form if a glass rod moistened with hydrochloric acid is held above the end of the open tube. Certain ammonium salts evolve ammonia even without addition of soda; several of them are vola- tile as such. 5. Baktta, Ba 0. Its occurrence in the mineral kingdom^ Baryta always occurs in combination with other bodies. a. With sulphuric acid in Barite {barytes, heay spar), 3, — Ba S 0*, sometimes containing Ca S 0* or Sr S 0*; Barytocelestite, 3, — Ba S 0' and Sr S 0* in varying proportions. h. With carbonic acid in Witherite, 1,— Ba C 0' ; Barytocalcite, 1, — Ba C 0' + Ca C 0', always containing some Mn C 0'. Bromlite, 1, — contains the same constituents as barytocalcite. EXAMINATION! FOE BARYTA. 113 c. With silicic acid in Harmotome, I-II, 1,— Ba 0, KV 0=, 5 Si 0" + 5 H' 0; frequently a little CaO, K^'O, Na'O; Edingtonite, II-III, 1 Or, — a similar silicate. Brewsterite, I A, 1,-3 E 0, 2 AP 0% 11 Si 0" + 10 ff 0; R = 2 Sr 0, 1 Ba 0; with some Ca 0. Hyalophane, vide potassa. Baryta also occurs in certain feldspars, and in Psilomelane, barytiferous, \ Braunite, /■ vide manganese. Hausmannite, ) Since barite sometimes forms an ingredient in ores dressed on a large scale, and is also added in many smelting processes, baryta frequently forms a constituent of slags, which also occasionally contain sulphide of barium. Examination for Baryta. Baryta colors the flame yellowish-green; fuses alone on coal and is absorbed; the same with soda. With cobalt solution it melts to a brown bead which soon crumbles to a light gray powder. SULPHATES. a. Barite fuses only on the edge; colors the flame yellowish- green ; on coal in the E. F. is reduced to sulphide. With ,soda on platinum foil it fuses to a clear mass ; on charcoal it at first gives a clear bead with soda, which spreads out on continuing the blast and sinks with ebullition into the coal as a strongly hepatic mass. This cut out, laid on silver foil, and moistened thoroughly, gives a black spot of sulphide of silver. When barite contains Ca S 0* and a little is treated with soda in powder, the sulphate of baryta and the soda with the sulphuric acid from the lime sink into the coal, leaving the lime, which generally adheres to the edges of the annual rings, and can be recognized b> becoming quite luminous when treated for a while with the 0. F. b. Barytocelestite fuses with great diflSculty, but more easily thai barite, and colors the flame yellowish-green. The difference in the fusibility of the two can best be tested by pulverizing each with a little water, forming two thin crusts from the paste, according to p. 71, and then testing one of these after the other at the same temperature. With soda it reacts like barite, as strontia also goes 114 PLATTlSrEE'S BLOWPIPE ANALYSIS. into the coal. The presence of strontia is detected by a special test, which will be given here for the sake of connection. A little of the mineral is pnlverized with some purified graphite and water in the mortar, dropped upon coal, and treated after careful drying for some time with the E. F. on both sides. The resulting compound of sulphides of barium and strontium is decomposed iu a porcelain vessel with hydrochloric acid, the solution evaporated immediately to dryness, the salt dissolved in a few drops of distilled water, and then alcohol added until a spirit of about 80° is obtained. Upon setting fire to this and constantly stirring it with a glass rod, the flame of the alcohol is colored red with chloride of strontium- Even when the amount of strontia is trifling the color may be dis- tinctly seen if the solution of the salts in alcohol is absorbed by a ball of cotton wrapped about a loop of platinum wire and then set on fire. Here, as in the case of the blowpipe flame, carer must be taken to avoid any impurities arising from soda salts, which would color the flame intense reddish-yellow and more or less conceal the red flame resulting from any trifling amount of strontia. CAEBONATES. a, Witherite fuses easily to a bead, coloring the flame distinctly yellowish-green and acquiring an alkaline reaction. With soda fuses very easily and goes into the coal. Dissolves in dilute hydrochloric acid with effervescence. h. Barytocalcite is almost infusible, but produces an intensely yellowish-green flame. Strongly, heated it frits on the surface, becomes bluish-green (Ba Mn 0'), and shows an alkaline reaction. With soda the lime separates, while the rest sinks into the coal. With borax and S Ph (with addition of nitre, p. 173), a feeble but distinct manganese reaction is obtained. Bromlite behaves very similarly. The presence of lime in barytocalcite and bromlite can be detected by cautiously bringing the powdered minerals, moistened with hydro- chloric acid and spread on a loop of platinum wire, near the tip of the blue flame. During the first action of the flame, distinct streaks of the yellowish-red .lime flame are seen, which are, however, very soon concealed by the baryta. BAE1-TA — SILICATES — MANGANESE OKES. 115 SILICATES. lu silicates baryta cannot be detected, either by the flamCj or by its behavior with soda; nor is there any other means of determining it with certainty in the dry way. The wet way must therefore be used in connection with the dry method. The silicates above named, liarmotome, edingtonite, and ireiu- sterite, can be decomposed by hydrochloric acid, and, after filtering out silicic acid, the bases may be detected. Upon adding bisulphate of potassa, or a few drops of sulphuric acid, to the solution the baryta and strontia are precipitated as sulphates, and the only question is whether, we have both of these salts, or which alone. To determine this the precipitate is thoroughly washed on a filter with hot water, spread on coal, dried with the blowpipe, and then heated strongly until it adheres. The crust thus formed is tested in the forceps as to fusibility and the color it imparts to the flame. If it fuses to a bead, and gives a red flame, it is strontia; if it fuses only with difficulty on the edges, and colors the flame yellowish- green, it is baryta; while if it is less fusible than in the former case and more fusible than in the latter, it is quite certain to be a mix- ture of both. In order to remove all doubtfulness from the reaction it is, however, necessary to wash the precipitate so thoroughly that no soda caa be present, as this would alter both the fusibility and the flame. If the yellowish-green flame has plainly shown baryta, but there is still a doubt whether strontia may not be present, the already tested assay, or a fresh portion of the precipitate, is to be treated with graphite on coal, exactly as directed for barytocelestite, p. 114. The manner in which the other bases are detected in harmotome and brewsterite, and the method o± examining dressed ores and - slags with the help of the wet way, is described in the examination of silicates containing lime, under lime, p. 138. MANGANESE ORES CONTAINING BABTTA. In the three manganese ores named, iraunite, liausmannite, and psilomelane, the trifling amount of baryta can sometimes be detected simply by the feeble, yet distinct, baryta flame produced by a small splinter, either alone, or moistened with hydrochloric acid. If this gives no satisfactory result, a not too small amount of the mineral ia dissolved in hydrochloric acid, diluted with water, filtered if necessary, and tested with bisulphate of potassa or sulphuric acid. If a pre- cipitate results, it can be collected on a filter and tested, as befort described. 116 plattjs'eb's blowpipe axaltsis. 6. STEomriA, Sr 0. Its occurrence in the mineral kingdom. Strontia occurs : a. With sulphuric acid in Celestite, 3,— Sr S 0*, sometimes with a little Ba 0, Ca 0, Fe' 0', and W 0; Barytocelestite, vide baryta; Also occasionally in trifling quantity in barite, vide baryta. h. With carbonic acid in Strontianite, 1, — Sr C, containing frequently more or less Ca 0, Mn^O^ Fe'O', andff 0; Also in trifling quantity in aragonite, vide lime. c. With silicic acid in Brewsterite, vide baryta. Ezamination for Strontia. Strontia colors the flame crimson, gives a very strong light, and with soda sinks into the coal. Ignited with cobalt solution it becomes black or dark gray. SULPHATES. Celestite (which generally decrepitates when crystallized) fuses to a milk-white bead, coloring the flame red, p. 74. On coal in R. F. it spreads out and is changed to a diflScultly fusible, hepatic mass, consisting chiefly of sulphide, which with hydrochloric acid easily yields strontium chloride and gives an intense red flame, more dis- tinctly than the mineral. With soda fuses to a clear mass, which sinks into the coal with efEervescence; any trifling admixture of Ca will be separated and behave as stated on p. 113. The mass out out from the coal gives a Bulphur reaction on silver. The method of detecting strontia in barytocelestite and certair barites has been given under baryta. CABBONATBS. a. Strontianite swells in the blowpipe flame, putting forth ramifi- cations which glow with a bright white light and fuse only on the thinnest edges; the flame is colored red, and most strongly where the assay is most luminous. After ignition the assay reacts alkaline on red litmus paper. Strontianite dissolves with eflfervestence in dilute hydrochloric acid, and if the solution is evaporated to dryness and the resulting LIME. 117 chloride of strontium treated with alcohol, or held in the blowpipe flame on platinum wire, it produces a red flame. According to yon Kobell a bit of strontianite moistened with the acid and simply held in the candle flame will produce a red color. The purity of strontianite can readily be tested by fusion with soda. The pure mineral fuses to a clean mass and goes into the coal, but if any Oa is present it will be separated and left on the surface, as with barite. b. Aragonite sometimes contains a little strontia, which can be detected by heating in the forceps a fragment of the assay, previ- ously decrepitated in a matrass; it is infusible, but colors the flame more intensely red than an equally large piece of calcite. To detect it more certainly, a sufficient amount is dissolved in dilute hydro- chloric acid and the strontia precipitated with a few drops of sul- phuric acid. The precipitate is collected and treated as directed on p. 114. It fuses to a bead and colors the flame red like sulphate of strontia. Strontia is detected in hrewsterite as already directed, p. 114. 7. Lime, Ca 0. Its occurrence in the mineral kingdom. Lime is of quite frequent occurrence and is found: a. As chloride in Tachydrite, 1,-3 Mg CP + Ca CP + 12 H^ 0. h. As fluoride in Fluorite {f,uor spar), 1-2, — Oa F"; Pachnolite, 2 Na P, 2 Ca P', AP F' + 2 H' 0. Yttrocerite, vide Yttria. c. With sulphuric acid in Anhydrite 2,— Ca S 0*, frequently containing a little Si 0', C 0', Fe'' 0», and H^O: G-ypsum, 1-2, — Ca S 0* + 2 H' 0, and occasionally impurities; Polyhalite and Syngenite, vide potassa; Glauberite, mde soda. d. With nitric acid in Nitrocalcite,-Ca (N 0')' + H' 0. e. With phosphoric acid, and at the same time as calcium with fluorine and chlorine in Apatite 1,— phosphate of lime with chloride or fluoride of calcium, — Oa (F, 01)' + 3 Ca' P' 0°; many specimens contain some Fe' 0', and sometimes Mg 0. 118 plattner's blowpipe analysis. Staffelite, a crystalline lime phosphate with Ca C 0' (up to 9 per cent.). Osteolite contains besides lime phosphate, Mg O, Al» 0', Fe' 0=, alkalies, Si 0^ (to 9 per cent.), C 0' and H^ 0. Brushite, metabrushite, isoolasite, oollophanite, all hydrous lime phosphates. /. With carbonic acid in Calcite, 1, — Ca 0^ with occasionally isomorplious carbonates of Mg 0, Mn 0, Fe 0, and sometimes a little H" 0. Aragonite, \, — Ca C 0\ with trifling amounts of Sr C 0% Pb (tarnovicite), and H'O; sometimes colored by Cu, Co, and Mn. Gay-Lussite, vide soda ; Plumbooaloite 1, — Ca C O' with several per cent, of Pb C 0=. Dolomite (pearl spar, pt. ; brown spar, pt. ; tharandite), 1, — Ca C 0' + Mg C 0', with small quantities of Fe C 0' and Mn C 0'- In brown spar (ankerite) both carbonates occur, with very variable amounts of Fe C 0' and Mn C 0'. Barytocaloite and bromlite, vide baryta ; Manganocalcite, \ . , „, ° , .. fmde manganese: Ehodochrosite, i Tyrolite, vide arsenate of copper. Uranothallite, liebigite, voglite, vide uranium. g. With oxalic acid in Whewellite 1,— Ca C' 0' -f- H' 0. h. With boric acid in Hydroboracite, 1,— Ca 0, Mg 0, 3 B= 0' + 6 H= 0. Hydroborocalcite (hayesine), 1,— Ca 0, 2 B' 0' + 6 W 0. Colemanite— 3 Ca 0, 3 B^ 0= + 5 W 0. Pandermite— 4 Ca 0, 5 B= 0' + 8 H' 0. Ehodizite, probably K' 0, 2 A? 0\ 3 B' 0'; XJlexite, vide soda. i. With arsenic acid in Haidingerite, 1,— H'' 0, 2 Ca 0, As' 0' + H= 0.* Pharmacolite, 1, — H' 0, 2 Ca 0, As' 0^ + 5 H' 0;* in picropharma- colite Mg also ; wapplerite is likewise a lime magnesia arsenate. Berzeliite, 1, — 3 Ca 0, As' 0=; part of the Mg replaced by Mn (perhaps also 4K 0, As' 0'). Eoselite, 1,— 3 K 0, As' 0' + 2 ff ; K = Ca 0, Co 0, and Mg k. With tungstic acid in Scheelite, 1 (with separation of W 0") — Ca W 0'; often containing Fe and Mn. I. With antimonic acid iu Eomeite, 3,-3 (Ca 0, Sb' 0») + 5 Ca 0, 3 Sb' 0', with small quan- tities of Mn 0, Fe 0, Si 0'. * Part of the water " chemically combined." LIME. 119 m. With nioiic acid in Pyrochlore from Miask^Nb' 0' and Ti 0' combined with Ca 0, Ce' 0', Th 0', and a little Fe 0, as well as with Na, F, and a little H" 0. Pyrochlore from Brevig contains also XJ' 0' and Mn 0. Pyrochlore trom Fredriksvarn, according to Bammelsberg, Is free from TJ' 0' and ThO'. Pyrochlore from the Kalserstuhl contains K» 0, but neither Ti 0' nor Th 0'. n. "With titanic acid in Perofskite, 2,— Oa 0, Ti 0% with a little Fe 0, Mg and Mn 0. 0. With silicic acid in a. Anhydrous silicates, which yield in the matrass no water, or only traces : WoUastonite, II, 1 G,— Ca 0, Si 0', and often with Mg 0, Fe' 0% and H' 0. Lime-alumina garnet (grossularite, essonite, cinnamon stone) 1, 3, — 3 Ca 0, AP 0', 3 Si 0', mixed with more or less 3 Ca 0, Fe» 0', 3 Si 0"; Ca is replaced in part by Mg 0, Fe 0, Mn 0. Lime-iron garnet (aplome, allochroite, colophonite, melanite) I, 2, — 3 Ca 0, Fe" 0', 3 Si 0'; with small quantities of AP 0\ Mg 0, FeO. Chromium garnet (ouvarovite) III, 3, the same composition as lime- alumina garnet, AP 0' being partly replaced by Cr" C and Fe'' 0^ Vesuvianite (idocrase, egeran, wiluite, in part), I A, 2, essentially lime-alumina silicate. Montloellite, II-III, 1 G— 2 CaO, Si O' -I- 2 Mg 0, Si O', with a little Fe O. Many members of the pyroxene group. These are isomorphous mixtures of Ca 0, Si 0=; Mg 0, Si 0=; Fe 0, Si 0"; and AP 0'; besides Mn 0, Fe= 0' and Cr" 0=. Diopside (Salite), I-II, 2,— Ca 0, Si 0" -|- Mg 0, Si 0', with a little Fe and Mn 0. Malacolite, of similai; composition, richer in Fe 0, Si 0'. Hedenbergite, I A, 2,— Ca 0, Si 0" + Fe 0, Si 0". Aluminous pyroxene (augite, fassaite, omphacite). SchefEerite and jeffersonite are pyroxenes rich in manganese; the latter also contains zinc. Diallage, II-III, 2. Babingtoiiite, I A, 3. Scapolite (wernerite), I-II A, 1, — essentially lime-alumina silicate with Na' ; rarely Fe 0, IP 0, CI, and S 0'. Sarcolite, I A, 1 G; meionite, I A, Ij gehlenite; melilite, I, 1 G; iiumboldtilite, I-II, 1 G, are similar. Epido.3 (bucklandite, pistacite), of varying fusibility, 2. Essen- 120 PLATTNER'S blowpipe AMALTSI8. tially lime-alumina silicate with admixture of . Mg 0, Fe 0, Fe' 0', Na= 0, K' 0, H= 0, F, and B'' 01 (The presence of the last two constituents is not generally mentioned by other authorities. Transl.) In piedmontite (manganepidot) Al' is mostly replaced by Mn' 01 Anorthite (lime feldspar), II,— Ca 0, AP 0', 2 Si 0"; often with a little Fe' 0', Mg 0, Na' 0, K' 0. Margarite, II A, 3, contains H' 0, AF 0=, Fe' 0^ Ca 0, Na' 0, Si 0'. Labradorite, oligoclase, vide soda. Cacholong, tremolite, actinolite, vide magnesia. /?. Anhydrous silicate, with B' 0': Danburite, I-II, 1,— CaO, B' 0', 2Si0'; a little AP 0= replaces some B' 0'. y. Hydrous silicates : Prehnite (coupholite) I A, 2,-2 Ca 0, Al' 0', 3 Si 0' + H' 0, and usually Fe' 0^ Okenite, I A, 1 G,— Ca 0, 2 Si 0' + 2 H' 0. Scolecite (lime-mesotype) I A, 1,— Ca 0, AP 0^ 3 Si 0' + 3 H' 0. Laumontite, I A, 1 G,— Ca 0, AP 0=, 4 Si 0' + 4 H= 0. Thomsonite, I A, 1 G ; chabazite, I A, 1 ; stilbite, I A, 1 ; heulan- dite, lA, 1; epistilbite, I A, 1-2 ; are mixtures of lime-alumina silicate with soda-alumina silicate ; the acidity of the mixtures varies. Gmelinite, I A, 1 G ; herschelite, I, 1, also belong here. Apophyllite, phillipsite, vide potassa. S. Hydrous silicates containing horic acid : Axinite, I A, 3,-2 H' 0, 8 K 0, 4 E' 0% 11 Si 0'; E = Ca 0, Fe 0, Mn 0, Mg 0; R' 0' = Al' 0% B' 0^ Fe' 0'. Datolite, I A, 1 G,— H' 0, 2 Ca 0, B' 0% 2 Si 0'. Botryolite, I A, 1 G,— H' 0, 2 Ca 0, B' 0=, 2 Si 0' -f- H' 0. Howlite (silicoborocalcite) I A, 1 G,— 4 Ca 0, 5 B' 0% 2 Si 0' + 5H'0. e. Silicates containing titanic acid : Titanite (sphene, greenovite) II A, 2,— Ca 0, Ti 0' + Ca 0, Si 0', including a little Fe and Mn ; guarinite is of similar compo- sition. Keilhauite (yttrotitanite), I A, 1,-2 Ca O, B= 0", 5 (Si, Tl) 0' ; B^ 0' = Y' 0>, Al' 0', Fe' 0^ Ce» 0'; also a little K' o. Schorlomite, II, 2. Lime-Iron garnet rich in titanium. Lime forms an essential constituent of several other natural sili- cates, besides those above named, and these have been for the most part already mentioned, under potassa, pp. 101, 10?, aiul coda, pp. EXAMINATION FOR LIME. 12 L 106-107, while the remainder will be given under magnesia and alumina. Oalcite, dolomite, and fluorite being of very frequent occurrence in ore-bearing veins, lime often forms a considerable ingredient in dressed ores, especially when stamped dry, and consequently also in the slags resulting from smelting these ores; the amount of lime in the slags is also frequently increased by the addition of calciferous fluxes, necessary for smelting many ores. These slags occasionally contain Ca S and Ca F^ Examination for Lime. Lime colors the flame yellowish-red, glows very brightly and is infusible. Treated on coal with soda, the soda sinks into the coal, leaving the lime behind. Ignited with cobalt solution it becomes gray. FLTTOEIDE OF CALCIUM AND ITS COMPOUNDS. a. Fluorite frequently phosphoresces with a violet or greenish light, and generally decrepitates in the matrass. In the forceps it fuses to a bead, and after long heating colors the flame intense yel- lowish-red, p. 74. On platinum foil and charcoal fuses with soda tc a clear mass, which is opaque on cooling, vide also p. 88. With gyp- sum, barite, or celestite, it fuses easily on coal to a clear bead, opaque on cooling. Dissolves very easily in considerable quantity in borax and S. Ph., but the glass becomes opaque when supersaturated. Treated in the open tube with fused S. Ph., it evolves hydrofluoric acid, vide fluorine. i. Yttrocerite, vide yttria. SULPHATES. a. Anhydrite yields no water, or only traces, in the matrass, while gyvsum yields water and becomes milk-white. B. B. both behave as follows : fuse with difficulty to an enamel- white bead and color the flame red, but feebler than celestite. On coal in E. P. yield sulphide of calcium, which reacts alkaline on red litmus paper and evolves a hepatic odor. In borax on platinum wire dissolve to a clear glass, colorless unless oxide of iron is present, when the hot glass appears yellow. A su- persaturated bead is opaque on cooling. If tested with borax on coal the saturated bead becomes yellow, owing less to a little iron than to the formation of sulphide of sodium. With soda on coal cannot be 133 plattner's blowpipe analysis. fused to a clear mass; distinction from barite and celestite. Tliey are indeed decomposed, but the lime remains as an infusible mass, while the sulphate of soda and the excess of soda sink into the coal. With fluorite they fuse to a clear bead, which is enamel-white on cooling and swells up and becomes infusible on continuing the blast. b. Polyhaliie, containing sulphates of Ca, Mg, K, yields water and fuses on coal to an opaque red bead, which in the E. F. becomes white and forms a hollow crust, with a salt and somewhat hepatic taste. Fused on platinum wire a trifling amount of N a 01 causes a soda flame, so that the potassa can only be seen by using cobalt glass or indigo solution, vide potassa. In borax dissolves easily with efiervescence to a clear bead, some- what colored with iron, which is opaque when very much is added In S. Ph. dissolves easily to a clear, colorless bead, opaque on cooling, which shows no iron color unless a great deal is added. With soda it is decomposed, yielding an earthy mass, which in the K. F. is yel- lowish from Xa S. With fluorite fuses to an opaque bead. Lime and magnesia can only be separated by the wet way, and each tested by itself with the blowpipe. The mineral is dissolved in dilute hydrochloric acid, a trifling amount of sesquioxide of iron precipitated by ammonia, and then the lime precipitated with oxalic acid and the magnesia with salt of phosphorus. c. Glauberite, containing Ca S 0' and some Na' S 0*, which is recognized by the soda flame, vide soda, decrepitates in the matrass with some violence and yields very little water; at incipient redness it fuses to a clear mass, yielding nothing volatile. On coal becomes at first white, then fuses to a clear bead, opaque on cooling. In the R F. the bead becomes infusible and hepatic, and after blowing longej the Xa S goes into the coal and leaves the lime behind. In borax and S. Ph. dissolves in large quantity with effervescence to a glasp which is opaque on cooling. It is decomposed with soda on coal to a hepatic mass, which sinks in and leaves the lime. With fluorite fuses like gypsum. NITBATB OF LIMB, In the matrass yields water, and when strongly heated nitrous acid. On platinum wire gives a strongly luminous mass, which •colors the flame yellowiflh-red. Deflagrates slightly on coal, leaving a white, earthy, alkaline mass, which does not sink into the coal with soda. LIMB — PHOSPHATE — CARB0KATE8, 123 PHOSPHATE OF LIME WITH CHLORIDE A]SrD FLUORIDE OF CALCIUM. Apatite sometimes phosphoresces in the matrass. {Eupyrchroite from Crown Point, K Y., shows green phosphorescence.) In the forceps fuses with difficulty on the edge to a translucent glass, not coloring the flame distinctly. The fine powder moistened with sul- phuric acid produces a transient bluish-green flame, p. 76. The phosphoric acid can also be otherwise detected, vide phosphoric acid. In borax dissolves slowly to a clear glass, frequently yellow from iron while hot, and which can be made opaque by flaming with a certain degree of saturation; when more is added it becomes opaque of itself on cooling. In S. Ph. dissolves largely to a clear glass, which when nearly saturated becomes opaque and shows crys- talline facets on cooling; these are less distinct than those produced by phosphate of lead in this salt. A fully saturated glass becomes milk-white without showing facets. With equal parts of soda swells with effervescence to an infusible mass, more soda goes into the coaL Any manganese present can be detected with soda and nitre on platinum foil, vide manganese. Chlorine and fluorine, if not in too small quantities, are found by the tests given elsewhere. To ascertain further the presence of lime the powdered inineral ia dissolved in hydrochloric acid, a few drops of sulphuric are added, the acid solution diluted with three volumes of strong alcohol, and shaken. Sulphate of lime separates and can soon be filtered off; after being washed with alcohol it must react B. B. like gypsum. After removing the alcohol by evaporation, other ingredients, like alumina and oxide of iron, can be tested for. (The above solution cannot first be treated with ammonia, for the lime would go down as phosphate again.) To test the apatite for magnesia also, it must be fused in powder with soda and silicic acid, as will be given under the phosphoric acid, the mass treated with water, the carbonates of the earths and any residual silica dissolved in hydrochloric acid, the solution diluted with water, and the silicic acid, with any traces of alumina and sesquioxide of iron, precipitated with ammonia ; after which the lime is thrown down with oxalic acid and the magnesia with salt of phosphorus. The remaining phosphates of lime behave similarly; the hydrous ones yielding water in the matrass. CARBOKATES. a. Calcite. Decrepitates sometimes in the matrass, and when con- taining metallic oxides changes in color. In the forceps is infusible, becomes caustic, feebly luminous, and colors the flame red, but far 124 plattnee's blowpipe analysis. more feebly than strontianite. When afterward moistened with hy- drochloric acid it gives a distinct characteristic lime flame. After thorough ignition it has an alkaline reaction. Dissolves with effer- vescence in the glass fluxes and reacts like lime; if it contains me- taUio oxides they can be at the same time recognized, and then traces of manganese musi be specially tested for, vide manganese. With soda on platinum foil fuses to a clear mass, while the metallic oxides are separated; on coal fuses at first, but afterward most of the soda sinks in, leaving an infusible residue, which is luminous under a strong blast. Sometimes a sulphur reaction is obtained on silver foU, p. 321. b, Aragonite crumbles to pieces B. B. ; otherwise reacts like cal- cite, but when containing strontia gives a more intense red flame, and when containing lead does not give a pure red but a bluish flame, while with soda on coal in the K. F, it deposits a slight lead coat. This is the case with iarnovicite. c Oay-Lussite yields water in the matrass and then has an alka- line reaction- In the forceps fuses to an opaque bead and gives a strong soda flame. With the fluxes and soda reacts like carbonate of lime. • d. Plunibocalcite reacts like plumbiferous aragonite, but gives a stronger lead coat. e. Dolomite, and all compounds of carbonates of lime and mag- nesia, react like carbonate of lime before the blowpipe. To detect magnesia it is best to use wet analysis. Oxalate of lime, whewellite, ia converted into carbonate by feeble ignition, and its blowpipe reactions then resemble those of calcite. BORATES. Colemanite, liydrohoracite, and ulexite yield much water, and fuse in the forceps with slight intumescence to a clear glass; the first and second color the flame pale greenish, the third reddish-yellow ; moistened with sulphuric acid, all three produce the yellowish-green boracic acid flame, p. 75. Dissolve largely in soda and S. Ph. to i\ clear glass; also on coal with a little soda. With more soda they fuse to a bead which becomes milk-white and crystalline in cooling; with still more the bead spreads out and gives a white, crystalline mass on cooling. Lime and magnesia can only be separated in the wet way, by dis solving the powdered mineral in hydrochloric acid, diluting the acid LIME — ARSENATES — TUNGSTATE. 125 solution with water, and adding soda enough to combine all the boracic acid with itself, so that no borate of magnesia may be thrown down on adding ammonia. The solution, with free hydro- chloric acid, is then treated with ammonia in excess and the lime and magnesia successively precipitated with oxalic acid and. salt of phosphorus. ARSENATES. a. Haidingerite, pharmacolite, and picropharmacolite behave similarly. In the matrass yield much water, especially the latter. They also become opaque, and if a fragment is afterward treated in the forceps it fuses with intumescence to a white enamel, giving a light-blue arsenic flame. On coal in the E. P. fuse to a semi- transparent bead, sometimes bluish from cobalt, and evolve an arsenical odor. In borax and S. Ph. like lime, but on coal the arsenic acid reduces and evolves arsenical fumes. Wapplerite behaves similarly. Decomposed with soda on coal, CTolving arsenical fumes, while the soda sinks in and leaves the lime. If the residue obtained on the coal is dissolved in hydrochloric acid, the solution supersaturated with ammonia, and the lime precipitated with oxalic acid, the mag- nesia can be detected with salt of phosphorus. b. Berzeliite is infusible and becomes gray (giving probably a light-blue flame). With the fluxes like the above minerals, but colors the borax bead distinctly with manganese. To detect the magnesia the crust left by soda on coal should be dissolved in hydrochloric acid,' diluted with water, and the lime, magnesia, and manganese precipitated as described under the silicates. c. Roselite becomes blue in the matrass and fuses easily; the detection of the other constituents follows from the foregoing. TUNGSTATE OF LIME. Scheelite fuses on the edge to a semi-transparent glass, not color- ing the flame. In borax in 0. P. dissolves easily to a clear glass, which soon becomes milk-white and crystalline, and cannot be colored in the E. P., even on coal with tin. In S. Ph. dissolves easily in the 0. P. to a clear bead, colorless only when quite free from iron which treated in the E. P. becomes blue from the formation of bin- oxide on cooling. Varieties containing iron give a brownish glass in the E. P., which only becomes blue when treated with tin on char- coal. Tested with fused S. Ph. in the open tube gives a little hydro- 126 plattner's blowpipe analysis. fluoric acid. When a little of the powdered mineral is fused with four to five parts of soda in the platinum spoon and then dissolved in hot water, tungstate of soda and soda dissolve, leaving lime and a little sesquioxide of iron and manganese, which may be tested B. B. The manner of separating the tungstic acid will be given under tungsten ; as well as another simple method of detecting tungstic acid in combination. Antimonate of lime, romeite. — With soda on coal the antimonic acid is reduced and volatilizes, forming a white coat, while the lime remains and the excess of soda sinks into the coaL JTIOBATES. a. Pyrochhre from Miask yields only traces of water. In the forceps infusible, but becomes yellow, and gives a yellow flame mixed with much red (soda and lithia). With borax in the 0. F. a clear glass, reddish-yellow when hot, colorless when cold ; saturated to a certain degree, it becomes opaque and reddish-gray by flaming ; with more it becomes opaque of itself on cooling, and is yellowish to red- dish-gi-ay. Dissolves easily in S. Ph. in the 0. F. to a clear yellow glass, which in the E. F. becomes dark brownish-red, as if from fer- riferous titanic acid ; with tin the glass becomes violet. It is there- fore free from uranium.. No manganese reaction can be obtained. I. Pyrochhre from Fredriksvarn 'difiers somewhat from the above. According to Berzelius it behaves as follows : Alone it becomes light brownish-yellow, remains lustrous, and fuses with great difficulty to a blackish-brown slaggy mass. Dis- solved by borax in the 0. F. to a reddish-yellow clear glass, which can easily be made opaque by flaming, and is then yellow; with more the bead becomes opaque of itself on cooling. In the E. F. it becomes dark-red and can be flamed to a light grayish-blue enamel, sometimes with streaks of pure blue. I« S. Ph. it dissolves perfectly, at first, with some effervescence to a bead, which in the 0. F. is yellow while hot, but on cooling fine grass-green (uranium). In the E. F. this green becomes gradually dirtier and after a and Fe C OS (sometimes with Ca C 0= and Mn C 0'). Dolomite, vide lime ; Hydromagnesite 1,— 4 Mg O; 3 C 0= + 4 H' O. lanoasterite (a mixture of brucite and hydromagnesite. Dana.) h. With loracic acid in Boracite 1,-3 (3 Mg 0, 4 B' 0=) + Mg CP, incl. a little Fe 0; slassfurtite is massive boracite; Szaibelyite, 1-2,-5 Mg O, 4 B^ 0> + 3 Hs ; Bydroboraeite, vide lime ; Sussexite, vide manganese j Ludwigite, vide iron. i. With arsenic acid in Hoernesite 1,-3 Mg O, As» 0» + 8 H» ; ' Bcesslerite 1, similar to hoernesite ; Pioropharmaoolite, berzeliite, roselite, wapplerite, vide lime. h. With silicic acid : a. Silicates yielding in the matrass no water, or only traces : Olivine (chrysolite, peridote, forsterite, boltonite). III (II), 1 G, — 3 Mg 0, Si 0" + 2 Fe 0, Si 0% in varying proportions. As accessory constituents small quantities of Ca 0, MnO, Ni Al'O^Cr=O^SnO^TiO=(?); 132 plattker's bloavpipe analysis. Hyalosiderlte, I-II, 1 G, a variety of chrysolite rich in iron and therefore more fusible. Hortonolite likewise. Enstatite, III, 3,— MgO, Si 0'; rarely a little AV 0% Fe 0, Ca 0, Na'O, K'O; Bronzite, II-III, 3,— a;Mg 0, Si 0' + yFe 0, Si 0\ x < y; usually also APO^ CaO, MnO; Hypersthene (paulite), II-III, 3, of the same composition, but with more Fe ; Tremolite (grammatite), I-II A, 2,— aMg 0, Si 0' + yGa. 0, Si 0\ X < y; also a little AP 0' and Fe 0; Actinolite, of similar composition, but richer in Fe 0, Si 0'; Anthophyllite, III, 2,— a;Mg 0, Si O'' + «/Fe 0, Si 0\ x ; AUophane, III, 1 G,— AP 0", Si O' + 5 H» 0, with admixture of Cu ; Bole, II A, 2, of varying composition ; Pyrophyllite, III A, 3,— Al' 0', 3 Si 0= + H^ 0, or Al' 0', 4 Si O' + H' 0. Cimolite, III, 3, perhaps 2 Al" 0=, 9 Si 0' + 9 H' O ; Nakrit (kaolinite ?), Ill A, 1 ; earpholite, I-II A, 3 ; umbra. In certain of the above minerals is also some Fe' 0', Ca O, Mg 0, Na' 0. Besides the silicates enumerated there are many others in which alumina is to be regarded as an essential constituent ; part of them have been named under potassa, soda, lithia, baryta, lime, and magnesia ; in part they will be named under the other earths and the metals whose oxides, together with alumina, are combined with silicic acid. i. Aluminates : Spinel, oeylonite, chlorospinel, vide magnesia ; Chrysoberyl, vide glucina ; Heroynite, vide iron ; (Jahnite, kreittonite, vide zinc. Alumina is also a frequent constituent of ores and slags. Ezamination for Alumina. Alumina is infusible and does not color the flame. In soda it is insoluble; on coal the soda alone goes into the coal. With cobalt solution after long blowing it assumes a fine blue color. FLUORIDE OF SODIUM WITH FLUORIDE OF ALUMINIUM. a. Cryolite sometimes decrepitates in the matrass. In the open tube, heated so that the flame enters the tube, much hydrofluoric acid is evolved, which attacks the glass, while the con- densed water in the tube reacts acid with Brazil-wood paper. B. B. fuses very easily, yielding part of its fluorine and giving a strong soda flame. On coal fuses very easily to a clear bead, opaque on coolino- After blowing longer the bead spreads, the fluoride of ALUMIKA — HYDRATE — SULPHATES. 14X sodium goefe into the coal, and a suffocating odor of hydrofluoric acid is perceptible, while a crust of alumina remains, which assumes a blue color with cobalt solution. Dissolves largely and easily in borax, and S. Ph. to a clear glass, milk-white on cooling. Fuses with soda to a clear glass, which on cooling spreads out and becomes milic-white. I. Chiolite yields no water, fuses very easily, and behaves other- wise like cryolite. c. PachnoUte yields water which reacts strongly acid. Quickly heated it is decomposed with a crackling sound and yields white fumes that condense on the glass. ALUMINA. Corundum alone is quite unaltered. In borax dissolves with difiSculty, but perfectly, to a clear glass, colorless if no iron is present. With S. Ph. dissolves only in powder, and slowly, to a clear glass, and is not attacked by soda. The very finely-powdered mineral assumes a fine blue color with cobalt solution. When it is desired to examine it for Si 0^ Fe° 0', etc., it should he finely pulverized in the steel mortar, to avoid silica from the agate mortar, fused on charcoal with soda and borax, and further treated with hydrochloric acid, as directed on p. 93. According to H. Eose, on fusion with bisulphate of potassa it readily yields a mass soluble in water. HTDEATE OF ALUMINA. a. Diaspore yields a little water at first and more when heated to glowing. It decrepitates little, or not at all; Berzelius, however, examined a diaspore from an unknown locality, which decrepitated with violence, crumbling into lustrous, white scales, and only yield- ing water at a red heat. B. B. it is infusible. With the fluxes like alumina, and if notably ferruginous the borax bead is yellow. Finely powdered it assumes a blue color with cobalt solution. b. Gibbsite behaves like diaspore; when containing phosphoric acid it colors the flame pale green. SULPHATES. a. Felsoianyite, aluminite, and alumian. The two former yield in the matrass much water, and at a high temperature sulphurous and sulphuric acids, recognizable by the odor and with litmus paper. 141 PLATTITER'S blowpipe AlfALTSIS. With borax and S. Ph. like alumina. With soda an infusible, hepatic mass, and with cobalt solution a fine bltij. Alumian be- haves similarly, but yields no water. h. Alunite yields water and sometimes crumbles to powder, especi- ally when crystallized. More strongly heated a little sulphate of ammonia is sometimes sublimed, while sulphurous and sulphuric acids are evolved and render the glass cloudy. In the forceps gives a violet flame, becoming reddish-yellow further from the assay. If the soda reaction is too strong the potassa is easily found according to p. 103. Dissolves easily in borax and S. Ph. to a clear, colorless glass, but sometimes leaves a silica skeleton in the latter. Is infusible with soda, but gives on coal a hepatic mass. With cobalt solution a fine blue. c. Alunogen swells up in the matrass, yielding much water, and at a higher temperature sulphurous and sulphuric acids. The dehy- drated salt is infusible B. B., but frequently gives a soda or potassa flame. With fluxes like aluminite, but the borax bead is frequently yellow from iron. Gives a fine blue with cobalt solution, unless con- taining too much iron. The salt is easily soluble in water, and there- fore any other earths present can be readily found by proper reagents. d. Kalinite fuses in its water of crystallization and froths, yielding much water, the residue heated to redness evolves sulphurous and 8uli)hui'ic acids. The dehydrated alum is infusible B. B. and givei a potassa flame ; if this is prevented by soda the potassa is found according to p. 103. With the fluxes and cobalt solution like aluno- gen. e. Mendozite behaves like kalinite, but only gives a soda flame, in which no potassa can be detected. /. T^chermigite at first acts like the preceding two in the matniss, but with a stronger heat some sulphate of ammonia is sublimed. With the fluxes, etc., like kalinite. Mixed with soda and gently heated in the matrass, carbonate of ammonia is evolved. g. Picker ingite has been described under magnesia, p. 134. PHOSPHATES. a. Turquois in the matrass decrepitates, yields some water, and turns black. B. B. infusible, but assumes a brown, glassy appear- ance and colors the flame green, partly from phosphoric acid and partly from a little oxide of copper. Dissolves easily in borax and S. Ph. to beads, yellowish-green when hot and pure green on cooling ALUMINA — PHOSPHATES. 14S (copper and iron). The S. Ph. glass on coal with tin hecomei opaque and red from suboxide of copper. With soda swells at first and then is gradually dissolved to a semi- transparent glass, colored with iron. With more soda becomef infusible, and with still more in a good E. F. some copper is reduced The phosphoric acid can be detected by fusing the mineral with soda and silica, dissolving the mass in water and throwing down the phos- phoric acid with acetate of lead, vide phosphoric acid. From the residue, insoluble in water, other constituents can be easily found out, ^ifter dissolving it in hydrochloric acid, as directed for lazulite, p. 134. i. Peganite yields water in the matrass and assumes an impure rose color. B. B. turns violet, cracks at a high heat, and is infus- ible, but assumes a glassy appearance and gives a greenish flame, partly owing to phosphoric acid and partly to a little oxide of cop- per. The latter causes a momentary azure-blue when the assay is previously moistened with hydrochloric acid. Dissolves easily in powder in borax and S. Ph. ; the hot glass is yellow from iron, but nearly colorless on cooling. With cobalt solution the fine powder becomes blue. With little soda swells and fuses to a semi-opaque glass, colored green by ferrous oxide; infusible with more. Dissolves easily in hydrochloric acid, leaving a very little silica. The detection of phosphoric acid can be performed as with turquois. Fischerite, Evansite, and Gibbsit behave quite similarly. The greenish-gray peganite behaves like the preceding, but in the matrass becomes reddish, in the crucible loses 34.1 per cent., and in the forceps becomes reddish-white. It seems also to contain , somewhat more iron. The phosphoric acid in peganite can be detected in the same way as with turquois. c. Amhlygonite in the matrass yields some moisture, which at a high temperature is acid and attacks the glass. B. B. fuses very easily to a clear bead and gives a yellowish-red flame of lithia and soda. The pulverized mineral moistened on platinum wire with sulphuric acid gives a momentary bluish-green flame of phosphoric acid. Dissolves largely and very easily in borax and S. Ph. to a clear, colorless glass. With fused S. Ph. in an open tube yields hydrofluoric acid, vide fluorine. With little soda, fuses; with more, swells and becomes infusible. d. Wavellite in the matrass yields water, the last drops of which have an acid reaction on Brazil-wood paper. The glass is also attacked by the liberated hydrofluoric acid. Ignited in the covered 144 plattner's blowpipe analysis. platinum spoon it loses twenty-seven to twenty-eight per cent, of its weight. B. B. swells and frequently is divided into fine acicular particles, which radiate from one point and are quite infusible, but turn white, if the mineral was not already white, and produce a bluish-green, phosphoric acid flame, most distinct after moistening with sulphuric acid. With the fluxes and cobalt solution like alumina, but the strongly saturated borax bead sometimes shows a little iron, while a manganese reaction is frequently obtained with soda and nitre. la perfectly soluble in hydrochloric acid if free from silica. e. Variscite yields in the matrass considerable water and assumes a feeble rose color. B. B. quite infusible, but turns white and is unaltered in the E. F. The flame is tinged bluish-green (phos- phoric acid); frequently this coloration is so strong as to indicate copper, which can be confirmed by the blue flame obtained after moistening the assay with hydrochloric acid. With the fluxes reacts like wavellite; becomes blue with cobalt solution. Fused on coal with soda, the fused mass decomposed by hydrochloric acid, and the solation evaporated to dryness, a mass is obtained which dissolves perfectly in water; it contains therefore no silica. If another portion is fueed on coal with soda and silica, as described above for turquois, and further treated in the wet way, in addition to alumina trifling quantities of sesquioxide of iron and chromium and of magnesia can be found and the phosphoric acid detected with certainty. MELLATE OF ALUMINA. Mellite yields water in the matrass, and when heated to redness chars and emits a burnt odor. In the forceps and on coal bums white and then behaves like pure alumina with the fluxes, etc. SILICATES. The silicates under a and P, and the alumina-bearing silicates enumerated under the alkalies and preceding earths, after being tested for water in the matrass and as to fusibility, difier considerably in their behavior ; the following remarks, however, apply generally to silicates rich in alumina. They dissolve with difliculty in borax to a clear glass, more or less yellow when iron is present. With S. Ph. they are slowly decomposed and generally only when powdered, the bases dissolving and the sUica remaining behind W hen alkaline bases are present the bead opalesces on cooling. With ALUMINA — SILICATES. 145 a little soda they generally fuse to a "bead, but with more soda give a slag-like mass, provided the bases are not combined with a high pro- portion of silicic acid. Cobalt solution can only be employed when the siUcabe is infusible and contains little or no coloring metallic oxides and also not much magnesia. An infusible silicate of alumina free from these ingredi- ents often assumes a fine blue color when treated in fine powder with cobalt solution. When it is neither possible to determine the sili- cate with the blowpipe, nor to detect alumina, the method described for lime, p. 138, must be adopted, and also for rocks, dressed ore, and slags, which are to be examined for alumina. The substance is decomposed by hydrochloric acid at once, or after fusion with soda and borax, then the silica and perhaps a trifle of baryta are separated, the protochloride of iron converted into sesqui- chloride of iron by nitric acid, and excess of ammonia gradually added to the acid solution, which contains the remaining bases. Alumina and sesquioxidc of iron are thus thrown down together, with any chromium present, which appears as sesqnioxide. When the substance contains much magnesia or protoxide of manganese, a very trifling quantity of these is also frequently present in the alumina and iron precipitate, which is filtered out, washed well with hot water, and heated while still moist with a solution of caustic potassa until the alumina is dissolved, leaving the dark-brown sesquioxide of iron either alone or mixed with the sesquioxide of chromium and exceedingly trifling quantities of magnesia and pro- toxide of manganese. The alkaline solution is diluted with water, the oxide of iron filtered out, and hydrochloric acid added to the filtrate until it reacts slightly acid, when the alumina is again pre- cipitated with ammonia and may be collected on a filter, well washed with hot water, and tested with cobalt solution. Should glucina, which behaves similarly with potassa and ammonia, be suspected, the alumina may be tested for it, as will be described under glucina. If the tests with fluxes have shown chromium, the separated ses- quioxide of iron should be examined for chromium, vide chromium. The method of detecting the other bases, lime, magnesia, and pro- toxide of manganese in the ammoniacal filtrate from the alumina, sesquioxide of iron, etc., is given under lime, p. 128 et seq. SILICATE OF ALUMINA WITH FLUOEIDB OF ALUMINIUM. Topaz {pyrophysalite and pycnite) are unaltered in the matrass. In the open tube with fused S. Ph. they yield hydrofluoric acid, vide fluorine. B. B. infusible, but the yellow topaz sometimes assumes a 146 plattnee's blowpipe analysis. feeble rose color. Dissolves slowly in borax to a clear glass, slightly yellow if iron is present. By S. Ph. they are slowly decomposed, the silica forming a skeleton, while the bead opalesces on cooling. Finely powdered they become blue with cobalt solution. With little soda they fuse with difficulty to a semi-opaque, bubbly slag; with more they swell and become infusible. According to Turner certain topazes fused on platinum wire with fluorite and bisulphate of potassa give a boraoic acid flame. ALUMINATES. The behavior of some of the above-named aluminates has been already stated under magnesia; that of the others will be described under glucina and zinc, 10. Glucina, Be 0. Its occurrence in the mineral kingdom. Glucina is not of frequent occurrence, being found only in com- bination with silica and alnmim. ^ a. With silicic acid in : Phenacite, III, 3,-2 Be 0, Si D' ; sometimes traces of Al' 0', Ca 0, and Mg ; Euclase, II-III A, 3,— H' 0, 3 Be 0, AP 0^ 2 Si 0"; with a little Sn 0', Fe 0, and F; Beryl (emerald) II-III, 3,-3 (Be 0, Si 0") + AV 0\ 3 Si 0"; some- times with a little Ca 0, Fe» 0=, and AP 0'; Gadolinite, some varieties, vide yttria. -Helvite, I-II A, 1 G, (evolving hydrogen sulphide), — (Mn, Fe) S + 3 [3 (Be, Mn, Fe) 0, Si 0°] ; danalite is similar, but with less Mn and more Fe; also some Zn; Leucophanite, vide soda. i. With alumina in : Chrysoberyl, III, 3,— Be + Al' 0', and sometimes a little Fe or Fe' 0\ Oa 0. Cr« 0', Ou 0, Pb 0, Si 0', and Ti 0^ Examination for Glucina. Glucina is infusible and is insoluble in soda. With cobalt solu- tion it becomes light bluish-gray. GLUCINA — SILICATES. 147 SILICATES. Phenacite yields nothing rolatile in tlie matrass. B. B. is in- fusible. Is dissolyed with extreme difl5culty by borax unless in fine powder, when it dissolres rather easily to a clear glass. In the strongly saturated glass white flocks are produced by flaming. The powder dissolres in S. Ph. and leaves a silica skeleton. With a little fioda a milk-white bead, with more it swells and forms an infusible white slag. After fusing the fine powder with soda and borax on coal, p. 93, and treating the compound with hydrochloric acid until the silioa is separated, the glucina may be readily separated and further ' tested. The acid solution is made slightly ammoniacal, when glucina and any traces of sesquioxide of iron are thrown down. They are collected on a filter, washed thoroughly, and heated while still moist with solution of potassa, until the glucina is redissolTed, leaving the oxide of iron. According to Schaflfgotsch particular care must be taken that the potassa solution does not boil, otherwise some of the glucina may remain undissolved. After diluting the solution with' water, filtering it, and making it slightly acid with hydrochloric acid, the glucina can be again thrown down .by ammonia and may then be tested for alumina. To this end it is filtered out, thoroughly washed, and then shaken in a test tube with a large quantity of carbonate of ammonia solution, whicl) dissolves the glucina and leaves the alumina. The latter, if found, may be collected, washed, and tested with cobalt solution. The ammoniacal solution of glucina is heated to boiling in a porce- lain vessel, when the glucina goes down as basic carbonate, and thia can be converted into pure glucina by ignition in the platinum capsule. Euclase is unaltered in the matrass and its water cannot be detected here, being only expelled at a very high temperature. B. B. swells up into cauliflower-like points, whitens and fuses with diffi- culty on the edge to a white enamel. Dissolves slowly in borax to a clear, colorless glass, which cannot be flamed opaque. If a fragment is employed it first swells with slight efiervescence and then whitens. Decomposed by S. Ph. with slight effervescence, leaving a white silica skeleton, while the glass remains clear and colorless, but opalesqes on cooling. A reduction assay with soda on coal yields traces of tin. With enough soda it fuses to a cloudy bead ; with more, to a bead which is clear only while hot ; with still more, sinks into the coal. Beryl is unchanged in the matrass. B. B. thin splinters become 148 plattker's blowpipe analysis. rounded and form a vesicular, colorless scoria ; transparent varieties become milk-white. Dissolves in borax to a clear glass, fine green when cold if chromium is present. By S. Ph. it is very imperfectly decomposed; the assay remains nearly unaltered, but diminishes somewhat, showing that some silica is dissolved as well as the bases. The cold glass opalesces and is green if chromium is present. It is dissolved by soda to a clear, colorless glass, and according to Berzelius the yellow mineral from Broddbo and Finbo yields visible traces of tin by the reduction assay. The method above given for phenacite is also employed in separa- ting the glucina from euclase and beryl. The precipitate obtained by ammonia, containing the alumina, glucina, and sesquioxides of iron and chromium, is treated as before with potassa solution, which leaves the oxides of iron and chromium. These are collected on a filter, washed, and tested. The alumina and glucina are separated as before. Other more accurate methods for the quantitative separa- tion of these earths {vide AusfUhr. Hmidbucli d. Anal. Ghent., H. Eose, vol. ii., p. 60, et seq.) need not be given here. Helvite yields a little water in the matrass, otherwise unchanged. B. B. intumesces strongly and fuses with difficulty to a dark-yellow to brown bead, not free from bubbles. Dissolves slowly in borax to a clear violet glass, nearly colorless in the K. F. It is" rather easily decomposed by S. Ph., yielding a silica skeleton and a colorless glass, opalescent on cooling. Swells at first with soda, then fuses to a black bead, chestnut-brown in the E. F. With more soda spreads out, sinks partly into the coal, and yields a sulphur reaction. With soda and nitre a strong manganese reaction. To detect the glucina the finely powdered mineral is dissolved in hydrochloric acid (paper moistened with acetate of lead shows that sulphuretted hydrogen is evolved), carefully evaporated to dryness, moistened with hydrochloric acid, dissolved iu boiling-hot water, and the silica filtered out. The filtrate is further treated as directed for phenacite, p. 147. The protoxide of magnesia can be precipitated in the ammoniacal filtrate from the glucina and sesquioxide of iron, either with sulphide of ammonium or a solution of S. Ph., and tested, p. 128. Danalite ; B. B. fuses readily on the edges to a black enamel With Boda on charcoal gives a slight coating of oxide of zinc (and a sulphur reaction on silver foil). Perfectly decomposed by hydro- chloric acid, with evolution of sulphuretted hydrogen and separation of gelatinous silica. Dana. Leucophanite fuses, according to Erdmann, to a clear bead. YTTRIA AND ERBIA. 149 inclining to violet, which can be flamed opaque. According to Dana it whitens and shows purple phosphorescence in the matrass; in the forceps phosphoresces and fuses with intumescence to a clear, colorless glass, also produces an intense soda flame. Dissolves easily in borax to a clear amethyst-red bead. Is easily decomposed by S. Ph. and leaves a silica skeleton. In the open tube with fused S. Ph. shows fluorine. With little soda it fuses to a cloudy bead, which spreads out and partly sinks into the coal with more. The lime and glucina may be easily found by the method given for phenacite; the ammoniacal filtrate from the glucina contains the lime, which is thrown down with oxalic acid. COMBINATION OF GLUCINA AND ALUMINA. Chrysoheryl is unaltered in the matrass. B. B. infusible, but heated in fine powder on coal becomes glassy on the edges. Dissolves slowly in borax and S. Ph. to a clear glass; in S. Ph. dissolves very slowly unless powdered. With soda only rendered dull on the surface; otherwise not attacked. The powder becomes blue with cobalt solution. The glucina is separated as described above for phenacite, etc. Only superficially attacked on fusion with soda. 11. Yttria, Y" 0', AND Eebia, E' 0'. Their occurrence hi the mineral kingdom. Yttria is but rarely met with and nearly always in common with oxide of erbium in various combinations. a. With fluorine in: Yttrocerite, essentially calcium fluoride with metals of the cerium and yttrium groups and 2.52 per cent. H^ (Naumann-Zirkel). b. With 2>hosphoric acid in: Xenotime, 3,— Y» 0^ P" 0», but containing also Ce' 0=. c. With niobic and tantalic acids in: Yttrotantalite (yellow and black), 3, and FCTgusonite (brown yttrotantalite in part, bragite), 3. They con- sist of tantalates and niobates (in varying proportions) of yttria and erbia, to which are joined : Ce' 0', V 0\ C:i 0, FeO, WOS SnOS H' 0; Samarskite, 1. Like fergusonite, but with more TJ' 0' and Fe 0, while Ca is almost entirely wanting. Has also frequently Th 0" and Zr 0^ 150 PLATXNEK'S blowpipe AKALTSI8. d. With niohic, tantalic and titatiic acids in : Euxenite, 3; polycrase, 3. Mixtures of hydrous niobates (tanta- lates) and titanates of yttria and erbia, with XT' 0', Ce' 0', and FeO. e. With silicic acid in a few silicates, part of which contain a little water. Gadolinite, III, 1 G — 3 K 0, Si 0' + R' 0", Si 0' ; R' 0' = Y' 0', Ce" 0% Fe' 0'; E = Fe 0, Be 0, Ca 0. Also has a little Th 0', Na' 0, H' 0; Muromontite, II, 1 G ; similar to gadolinite, but with rather much Al' 0», aa well as La" O' and Mg 0. Here also belongs bodenite. /. With titanic and silicic acids in: Keilhauite, vide lime. There are a few other mineralfl containing yttria, vide cerium. Examination for Yttria and Erbia. Both are infusible, glow brightly (the latter emitting an intense greenish light); they are not soluble in soda. FLUORIDE OF CALCIUM WITH FLUOEIDES OF YTTEIUM AND CERIUM lis VAETIlfG PEOPOETIONS. Tttrocerite from Finbo yields some water, which has a burnt odor. The dark variety becomes white in the matrass. On coal it is infusible, but becomes milk-white, or brick-red. With borax and S. Ph. a whitish-yellow bead while hot ; this can be flamed opaque at a certain degree of saturation. With a little soda fuses to a bead, with more becomes less fusible, and when still more is added the soda sinks into the coal, leaving an infusible mass behind. (Ber- zeliuB.) In open tube with fused S. Ph. yields hydrofluoric acid. The yttria in yttrocerite can only be detected by the wet process. A little of the very fine powder is digested with sulphuric acid in a platinum dish, stirred up with a platinum wire and heated over the spirit-lamp under a chimney, nntil all of the flnorine and then all of the superfluous snlphnric acid are expelled, leaving sulphates behind. These are dissolved in dilute hydrochloric acid, water is added, and the diluted solution filtered, if any sulphate of lime should remain undissolved. From the clear solution protoxide of cerium and oxides of lanthanium, didymium, yttrium, and erbium are precipi- tated by adding ammonia in slight excess, and the precipitate is filtered out. From the ammoniacal filtrate lime is thrown down by TTTKIA— FLUOBIDBS. 151 oxalic acid. The precipitate formed by adding ammonia is washed with hot water, until the wash water is no longer clouded by oxalic acid. (If it were necessary to examine this precipitate for alumina or glucina it would require to be heated moderately with a solution of potassa, and if it contained sesquioxide of iron this would be afterward removed by a dilute solution of oxalic acid, vide phosphate of yttria; but, according to Berzelius, yttrocerite contains none of these,) The well washed precipitate is then transfej-red to the larger porcelain vessel, p. 43, Fig. 63, or to a small Leaker glass, dissolved in a little hydrochloric acid, and diluted with water. In this solution is placed a crust of crystallized sulrhaie of potassa, so that it reaches above the surface of the liquid, and the whole is set aside for twenty four hours, or else the solution, if not too dilute, is treated with a quite concentrated solution of sulphate of potassa, prepared with the aid of heat, and the whole is allowed to cool. In either case the result is a liquid saturated with sulphate of potassa, in which yttria and protoxide of cerium form double salts with the potassa and Bulphuric acid. The yttria salt is soluble in the saturated solution of sulphate of potassa, while that of the protoxide of cerium is insoluble and falls to the bottom as a white powder. It is. filtered out, washed with a saturated solution of sulphate of potassa, and dissolved in boiling-hot water, after which the protoxide of cerium is thrown down with potassa solution by the aid of heat, filtered out, washed thoroughly, and then ignited in the platinum spoon. During ignition it oxidizes to eerie oxide and assumes, if pure, a lemon-yellow color ; but if it contains didymium it assumes a cinnamon-brown hue. Oxide of lanthanum is white and therefore any admixture of it would not be perceptible, but upon treating the ignited oxide with nitric acid, evaporating it to dryness, and igniting the dry residue with access of air, the oxide of lanthanum may be extracted with very dilute nitric acid and precipitated with solution of potassa, vide cerium, lanthanum, etc. The yttria remaining in the solution is likewise precipitated by potassa with the aid of heat, filtered out, and ignited. To test it for erbia it is dissolved in hydrochloric or nitric acid and ammonia - added in small portions, p. 150. If the fii'st precipitates appear yellow after ignition it may be assumed that the yttria contained erbia, since this haa a dark yellow color after ignition, while yttria is then pure white. Other coloring oxides are assumed absent. 153 plattnkk's blowpipe analysis. phosphate. Xenotime intumesces slightly and fuses with difficulty on the edges, coloring the flame distinctly bluish-green after being mois- tened with sulphuric acid. It dissolves slowly in borax to a clear glass, slightly yellow from iron while warm ; with moderate satura- tion, opaque by flaming; more highly saturated, becomes opaque on cooling. In S. Ph. it dissolves very slowly (distinction from apatite). The glass is colorless. With soda it is decomposed with effervescence to a light gray, infusible slag. To detect the yttria with certainty the very finely powdered mineral is mixed with four to five times its weight of soda and fused, either in separate portions on platinum wire, or in the platimim spoon, until it no longer effervesces. The fused mass is covered with water m a small porcelain vessel and heated to boiling over the lamp. Phosphate of soda and the excess of carbonate of soda dissolve, leaving the insoluble yttria and some sesquioxide of iron, which is present in the mineral as basic phosphate. After filtering out the residue and washing it thoroughly, phosphoric acid may be very readily detected by testing a little of the filtrate, vide phos- phoric acid. The residue of yttria and sesquioxide of iron may be dissolved while still moist in hydrochloric acid, diluted, and the bases thrown down as hydrates by means of ammonia; they are thoroughly washed, transferred to a test tube, covered with a dilute solution of oxalic acid, and heated nearly to boiling over the spirit-lamp. Both bases are converted into oxalates, and the oxalate of sesquioxide of iron being soluble can be readily separated by filtration from the insoluble oxalate of yttria, which appears as a heavy, white powder. This being also insoluble in pure water is washed thoroughly, dried, and ignited. A special test, p. 160, is necessary to determine whether the yttria is pure, or contains erbia, and for this the quantity of yttria must not be too small. The sesquioxide of iron in the fil- trate is separated by means of potassa, after some nitric acid has been added and the whole warmed. It is filtered out, washed, and tested B. B. with borax, if necessary. TANTALATBS. Yttrotantalite, yellow and black. According to Berzelius they behave as follows : Alone in the matrass they yield water and the dark varieties turn YTTRIA — TANTALATES — NIOBATES. 153 yellow. Strongly ignited they become white and the glass is attacked, while the expelled water turns Brazil-wood paper yellow at first and then bleaches it. B. B. infusible. Dissolve in borax to a nearly colorless glass, becoming opaque of itself with a large addition. Dissolve in S. Ph., leaving a white skeleton of tantalio acid, which on continued blowing also dissolves. The hlach variety from Ytterby gives a glass which assumes on cooling a feeble rose color, after treatment in E. F., owing to the presence of tungsten. The yelloio variety from Ytterby aflfbrds a faint but fine green bead, due to uranium. Yttrotantdlite from Finbo and Kararfvet affords a strong iron color, which obscures the uranium reaction. Soda decomposes, but does not dissolve them. On platinum foil they show manganese, and by reduction with borax and sod'i yield traces of tin The mineral from Finbo, however, contains so much iron that the tin cannot be thus detected. inOBATES. Fergusonite yields a little water in the matrass. B. B. on char- coal becomes first dark, then pale yellow, but is infusible. Dissolves with difficulty in borax to a glass which is yellow while hot, and if saturated, can be made cloudy and dirty yellowish-red by flaming ; the undissolved portion is white. Dissolves slowly in S. Ph. to a glass, yellow in 0. F., colorless in R. F., or inclining to red if well saturated ; it then is readily made cloudy by flaming, or on cooling, but this is not the case with a moderate addition of the mineral. The portion remaining undissolved is white. Fused with tin the S. Ph. glass remains colorless, but the undis- solved, white portion of the assay acquires a flesh-red shade. It is decomposed by soda without being dissolved, and leaves a reddish slag. Keduced with enough soda it affords some metallic tin. (Berzelius.) SamarsMte, according to G. Rose, behaves as follows : In the matrass decrepitates somewhat, glows, cracks open, and blackens. B. B. fuses on the edges to a black glass. With borax in 0. F. a yellowish-green to reddish glass ; in R. F. a yellow to greenish-black glass, becoming opaque and yellowish -brown by flaming. With S. Ph. in 0. F. a clear, emerald-green glass, unaltered in R. F. With soda on platinum foil a manganese reaction. Fused with bisulphate of potassa forms a fluid, red mass, which is yellow when cold. 154 plattner's blowpipe analysis. combination's with titanic and niobic acids. Euxenite is infusible. With borax and S. Ph. dissolves to glasses, yellow while hot, but the S. Ph. glass, not too slightly saturated, becomes yellowish-green on cooling, owing to uranium. (Scheerer.) Polycrase decrepitates in the matrass and gives traces of water. In the forceps glows and assumes a light grayish-brown color. Dis- solves in borax in 0. F. to a clear yellow glass, which assumes a brown color in R. P., especially in adding tin. With S. Ph. likewise dissolves to a clear, yellow to yellowish-brown glass, passing into greenish on cooling. In E. F. the color becomes darker. (Scheerer.) j^schynite yields some water and traces of hydrofluoric acid in the matrass. B. B. swells and changes from a black to a rusty brown color. Is rather easily dissolved by borax in 0. F. to a clear glass, yellow while hot, colorless on cooling. Treated with tin in E. F. this glass becomes blood-red. It dissolves less easily in S. Ph. ; a small addition affords a clear, colorless glass, which is readily made cloudy by separation of some white substance, when more of the assay is added. With tin in E. F. the glass asssumes an amethyst color. The mineral effervesce? with soda, but is not dissolved and yields nothing metallic. (Berzelius and Herrman.) It is suflBciently decomposed by sulphuric acid to show the reduction test with zinc. (Dana.) The wet process must be partly employed in order to detect with certainty the sepstrate constituents of the foregoing tantalates, niobates, and titanates, which may contain, in addition to the cor- responding acids, tungstic acid, and as bases, lime, yttria, zirconia, and oxides of cerium, lanthanium, iron, manganese, uranium, and tin. The following method is employed : 1. A sufficient amount of the very fine powder is fused in the pla- tinum spoon with eight parts by weight of bisulphate of potassa, p. 97, in several portions, each portion being treated until everything is melted to a clear fluid, when the mass is at once poured out upon the steel anvil. When all has been thus fused the mass is crushed in the steel mortar and then pulverized as fine as possible iii the agate mortar. The powder is warmed with sufficient water, not being allowed to boil, and the following ingredients then dissolve: Ca 0, Y' 0', Ce' 0', La' 0', Fe' OS-Mn 0, U' 0', while there remain as a white residue: Ta' 0', Xb' 0', W 0', Sn 0'. TTTRIA WITH TITANIC AND NIOBIC ACIDS. 155 If the mineral contains Ti 0', Zr 0', and Th 0', a portion of thego is also likely to remain undissolved. After filtration the residue is washed with hot water, to which a few drops of hydrochloric acid may well be added to secure the perfect separation of the sulphate of lime and sesquioxide of iron. 2. The residue is dried, finely pulverized, mixed with five vol- umes of carbonate of potassa, moistened with water, and melted in separate portions on stout platinum wire, Fig. 21, p. 20, until all is in quiet fusion, the melted mass being shaken off after each fusion. It is then pulverized and treated in a porcelain dish with cold water, to dissolve the excess of carbonate of potassa, the solution is drawn ofE with a pipette, and the residue treated with fresh water, which is heated to boiling. This dissolves Ta' 0% Nb' 0', W 0=, Th 0\ and most of the Sn 0" combined with potassa, leaving the greater part of the Ti 0' and all of the Zr 0' behind. The solution is filtered, the residue washed, and the solution added to the first, in case a part of the newly formed potassa salts was soluble even in cold water, the whole acidified with hydrochloric acid, evaporated to dryness at a moderate heat, and the dry mass treated with hot water, which dissolves the chloride of potassium and most of the stannic chloride, leaving behind Ta" 0°, Nb' 0', Th 0', and W 0% with a trace of Sn 0'. The solution, which may contain tin, is treated with a little sulphide of ammonium, shaken, and a few drops of dilute hydrochloric acid added, when a precipitate of sulphide of tin will form if tin is present. In order to free the tantalic or niobic acid from tnngstic acid and binoxide of tin, it is necessary to treat the mixture directly upon the filter with sulphide of ammonium. The neck of the funnel is closed ivith a cork, the still moist mixture covered with sulpludr of ammonium, and a watchglass placed over the funnel, when the whole is set aside in a warm place. After all of the tungstic acid and oxide of tin have been dissolved as sulphides the funnel is opened, the solution allowed to flow off, and the remaining acid thoroughly washed. If it is not white it .should be at once covered with dilute hydrochloric acid, while on the filter, so as to dissolve any traces of sulphide of iron present. The way in which it is further tested will be given under the examination for tantalum and niobium. Any thoria present can be separated by means of oxalic acid. The dissolved sulphide of tungsten, witli the traces of sulphide of tin which may be present, is thrown down by hydrochloric or liitrio acid, filtered out, and the precipitate, rich in sulphur, after being freed from the excess of sulphur on coal in 0. P. and then thoroughly 156 PLATTITBR'S BLOWPIPE ANALYSIS. ignited, is tested with S. Ph. on platinum wire for tungstic acid, and with soda and borax on coal for tin. The residue which remains after separating the Ta' 0', Nb' 0', and W 0°, and may contain Ti 0', Zr 0', and traces of Sn 0', is tested with S. Ph. on platinum wire for titanic acid; it is then tested with soda on platinum foil, and if during the fusion the fluid mass is clear where strongest heated, the residue consists only of titanic acid, but if not, since zirconia does not melt to a clear fluid mass with soda, it consists of titanic acid and zirconia, provided the test with S. Ph. has shown the presence of titanic acid. A portion of the residue may also be tested for tin by a reduction assay. 3. To the solution of the sulphates, containing free hydrochloric acid, ammonia is added in slight excess and with constant stirring; by this means (assuming that the solution contains also Ti 0', Zr 0', and Th 0') are precipitated, Ti 0', Y' 0=, Th 0', Zr 0', Ce" 0', La' 0', Fe' 0^ U' 0=, but Ca and Mn remain for the most part in solution. After filtering, the precipitate is well washed with hot water, lime is thrown down from the ammoniacal filtrate with oxalic acid and any manganese with S. Ph. or ammonium sulphide. 4. The precipitate obtained by means of ammonia is washed, dried, and dissolved with the aid of heat in sulphuric acid, diluted with an equal amount of water. Water is added to the clear solu- tion and the whole boiled, when any titanic acid present is thrown down, filtered out, and tested B. B. 5. The filtrate freed from titanic acid is neutralized with potassa, until it has but a very feebly acid reaction, and is then saturated with a concentrated solution of neutral sulphate of potassa, freshly prepared with the aid of heat. The whole is then allowed to cool, during which time a precijiitate, partly flocculent and partly pul- verulent, generally settles, consisting of basic sulphate of zirconia and sulphates of the oxides of cerium and lanthanium with potassa. If the mineral contains thoria it is also present in this precipitate, which is collected on a filter and washed with a saturated solution of sulphate of potassa. The filtrate contains the Y" 0°, Fe' 0^ and U^ 0°. Another vessel being placed below the funnel, the salts on the filter are washed with pure, boiling-hot water, which dissolves the double salts of cerium and lanthanium, leaving the basic sul- phate of zirconia and the sulphate of thoria. These two can only be separated conveniently in case a considerable quantity is treated, and then oxalic acid is used, in which the zirconia dissolves, while thoria is insoluble. The oxides of cerium and lanthanium are YTTRIA — SILICATES. 157 thrown down from their solution by potassa and then separated by means of dilute nitric acid, vide cerium. 6. The solution, which may contain Y' 0', Fe' 0', and U' 0', is treated with a slight excess of potassa, and these bases thrown down as hydrates. The precipitate is tranferred to a small filter, well washed with hot water, and then moderately heated in a small porcelain vessel with a dilute solution of oxalic acid, until the residue appears pure white. Ye' 0' and U" 0° dissolve, while the oxalate of yttria remains, and after filtration is washed, dried, ignited, and tested according to p. 149. After adding some nitric acid the Pe" 0' and U" 0' in the solu- tion are again thrown down with potassa, the whole warmed, filtered, washed, and the precipitate, while still moist, treated with carbonate of ammonia, which dissolves the U" 0^ and leaves the Pe^O'. .Prom the ammoniacal filtrate the U" 0' can be thrown down by boiling the fluid for some time, or by gradually adding hydrochloric acid to feebly acid reaction and then adding ammonia. The oxides thus separated may then be very easily recognized B. B. with glass fluxes. SILICATES. a. Gadolinite from Ytterby, Finbo, and Broddbo. With regard to these gadolinites and their behavior Berzelius makes the following observations : — They are of two kinds ; one (a) as vitreous as if it were a frag- ment of black glass; the other (^) splintery in its fracture and not BO largely conchoidal. It is apparently an intimate mixture of gado- linite and orthite. Var. a. If heated in a matrass, nearly to the melting point of the glass, the assay glows quickly, as if on fire ; it also swells somewhat, becomes li^t grayish-green, and cracks here and there if large. On coal the same ; it is infusible, but the thin edges become black in a strong flame. Var. (i. Alone it swells. up into cauliflower-like ramifications and becomes white, but seldom glows like variety a. Both varieties behave similarly with the glass fluxes, dissolving readily in borax and yielding a strong iron reaction. S. Ph. dissolves them with great difiBculty, the glass showing iron, and the fragment becoming rounded, but remaining white and opaque, so that the silica is not separated (chief distinction from gadolinite of Kararf- vet). With soda they are dissolved to a reddish-brown, half fused 158 plattneb's blowpipe analysis. slag, but variety yS fuses to a globule, when there is not too much eoda. No manganese reaction can be obtained. h. Gadolinite from Kararf vet. In the matrass yields a little water ; on coal whitens, and in a strong flame fuses to a dark pearl-gray or reddish, opaque glass, without swelling. Dissolves readily in borax to a clear glass, showing little iron. If saturated the opaque glass crystallizes on cooling and becomes gray, inclining to red or green, but the enamel-like opacity, afforded by yttria alone, cannot be pro- duced. Dissolves in S. Ph., leaving a silica skeleton and forming a nearly colorless glass, opalescent on cooling. With soda fuses with diffi- culty to a grayish-red slag, and on platinum foil gives a manganese reaction (Berzelius). According to Damour and Descloizeaux it glows brightly B. B., swells a little, fuses with difficulty on the edges, and becomes gray. c. Gadolinite from Hitteroe has been chemically exarfiined by Scheerer. A sufficiently large fragment heated to low redness in a partially closed platinum spoon, is observed to glow very strongly, the light spreading from one point throughout the whole. B. B. infusible ; with the fluxes shows iron and silica. According to Damour and Descloizeaux, 1. c, it glows when heated to redness, cracks, remains transparent, and is infusible. d. Mufomontite from Boden, near Marienberg, is said by Kerndt to behave like bodenite from the same place. e. Bodenite behaves, according to Kerndt, as follows : In the matrass yields a little water with a burnt odor and assumes a light brownish-yellow color. Heated in the platinum spoon some pieces glow suddenly, but more feebly than gadolinite and without decrepitating. When more strongly heated the assay cracks opeiL On coal it swells, turns dirty reddish-yellow, and finally fuses with intumescence to a dark, blebby glass. Dissolves easily and largely in borax to a clear glass, showing iron. Is very readily decomposed by S. Ph., leaving a silica skeleton in the glass, which shows iron, but gives no titanium reaction. With soda ftises with intumescence to a dirty yellow slag, and on platinum foil with nitre gives a manganese reaction. To detect yttria and the other ingredients, not to be recognized by the blowpipe, the foregoing silicates must be examined with the aid of the wet process. If not previously ignited they can be com- pletely decomposed by hydrochloric acid, and the following method may therefore be adopted : — 1. The very fine powder is heated with aqua regia, until com- ZIECONIA. 159 pletely decomposed ; the whole is then gently evaporated to dryness, moistened with hydrochloric acid, the resulting salts dissolved in hot water, and the separated silica filtered out, after which it is well washed and can be tested B. B. The solution may contain the following bases: Ca 0, Mg 0, Al' 0', Be 0, Y' 0=, Ce' 0", La' 0=, Fe' 0', Mn 0, and traces of K" and Na' 0. 3. To separate -these, excess of ammonia is gradually added to the acid solution and AV 0% Be 0, Y' 0=, Ce' 0% La' 0', and Fe' 0' are thrown down, leaving Ca 0, Mg 0, and Mn dissolved. The precipitate is collected on a filter, well washed, and the bases in the ammoniacal filtrate are separated by means of oxalic acid and S. Ph., p. 128, ei seq. 3. The precipitate formed by ammonia generally contains but little alumina and glucina and is dissolved in a small porcelain dish with just the necessary amount of dilute hydrochloric acid, the solution constantly stirred and excess of potassa added, after which the whole is heated, but not to boiling. At first all the bases are thrown down by the potassa, but AP 0' and Be redissolve, especially when the solution is heated. After diluting the whole with water, filtering and washing the precipitate thoroughly with hot water, the earths in the alkaline filtrate are separated as directed under glucina, p. 146. 4. The moist precipitate, containing Y' 0', Ce" 0', La' 0', and Fe' 0', is heated with dilute oxalic acid, which removes the Fe° 0'. The residue of oxalates is filtered out, washed, dried, and ignited with access of air; the resulting oxides are then dissolved in dilute hydrochloric acid and separated by means of sulphate of potassa, as already described under yttrocerite, p. 150. The sesquioxide of iron in the solution is thrown down by potassa, after some nitric acid has been added, and is tested B. B. SILICATES CONTAINIIfG TITANIC ACID. For Keilhauite, which belongs here, see p. 130. 13. ZiRCONiA, Zr 0'. Its occurrence in the mineral kingdom. Zirconia is of rare occurrence and is always found in combination, with bases and acids in 160 plattneb's blowpipe analysis. Polymignite, polyerase, vide yttria; Wohlerite, I, 1, silicate and niobate chiefly of Zr 0', Ca O, Na' O, with a little MnO, Fe O, Mg O, Ce'' 0=, H" 0, and F ; Eudialyte, 1, 1 U, silicate o{ Zr O", Fe O, Ca 0, Na^ 0, with some Na CI; (Erstedite, contains chiefly Zr 0', Ti 0=, Si 0^ and some Ca 0, Mg 0, Fe 0, and H' ; Catapleiite, 1, 1 G,— hydrous silicate of Zr 0^ Na» 0, and less Ca ; perhaps n(Na' O, Zr 02, 3 Si 0>) + Ca 0, Zr 0", 3 Si 0' ; Auerbachite, III,— 2 Zr 0= + 3 Si O', with little Fe and H^ j Zircon (hyacinth), III,— Zr 0' + Si 0', with little Fe 0. Of almost the same composition is malacon, with several per cent of H' Examination for Zirconia. ' Zirconia is infusible and of dazzling brilliancy when strongly ignited. It does not fuse together with soda. With cobalt solution it assumes a dirty violet color. Wohlerite yields some water. Strongly heated fuses quietly to a yellowish opaque glass and gives a strong reddish-yellow flame. With borax, S. Ph., and soda shows reactions for manganese, iron, silica. To detect zirconia and niobic acid with certainty, the very fine powder is heated with concentrated hydrochloric acid, until decom- posed. According to Scheerer.this dissolves Na" 0, Ca 0, Mg 0, Zr 0^ Fe' 0^ and Mn 0, leaving Si 0= and Nb' 0'. The residue, collected on a filter, well washed, and dried, is mixed and fused with five volumes of carbonate of potassa, being moistened and melted on platinum wire by separate portions, so that after each addition the melted mass is clear and fluid. The beads shaken pfE from the wire, which become opaque on cooling, are pulverized and treated first with cold water in a porcelain vessel to dissolve out the carbonate and silicate of potassa, and after the insoluble salt has settled and the supernatant liquid has been removed with a pipette, the residue is dissolved in boiling water, the solution added to the first solution, and the whole tested for the acids in question, as will be directed under tantalum and niobium; or else the solutions may be separately tested. The acid solution of the bases is treated with a slight excess of ammonia, which precipitates Zr 0', Fe' 0', and a little Ca 0. The precipitate is filtered off, washed with cold water, and warmed with dilute oxalic acid, wlien Zr 0" and Fe' 0° dissolve and leave the lime as oxalate. The latter is filtered out and some nitric acid added to the filtrate, after which Zr 0" and Fe' 0' are thrown down by potassa, collected on a filter, washed with hot water, dried, and gently ignited in the platinum spoon. It must then be triturated ZIUCOKIA. 161 in the mortar and is afterward digested with hydrochloric acid, which removes Fe' 0' and leaves the zirconia almost pure white. This can be now tested B. B., while the oxide of iron may be like- wise tested with borax, after precipitating it with ammonia. If the Zr 0" and Fe' 0' precipitate formed by potassa is digested with sulphide of ammonium the iron is converted into sulphide, and when the liquid is decanted from it, after a time, and the black residue mixed with an aqueous solution of sulphurous acid, the sulphide of iron is dissolved, leaving the zirconia nearly colorless. Of the other bases still dissolved in the ammoniacal solution, viz., Na" 0, Ca 0, Mg 0, and Mn 0, the Ca is thrown down with oxalic acid, ^and the Mg and Mn with S. Ph., as directed under lime and magnesia. The soda is indicated by testing the mineral in the forceps. Eudialyte yields a little water in the matrass. B. B. fuses easily to a greenish-gray bead ; according to Damour, to a translucent, dark green glass, and gives an intense reddish-yellow flame. With borax is easily dissolved to a clear glass which shows a little iron and ■cannot be flamed opaqne. Is easily decomposed by S. Ph., the silica skeleton swelling so as to alter the round shape of the bead. According to Berzelius, this forms a distinction between eudialyte and the otherwise similarly acting garnets. With little soda a diffi- cultly fusible glass ; with more goes into the coal. On platinum foil a manganese reaction. With a bead of S. Ph. containing oxide of copper a chloride of copper flame, vide chlorine. Gelatinizes with hydrochloric acid; the acid solution diluted and. boiled with tin, to reduce the iron to protochloride, imparts a deep orange to turmeric paper (reaction for zirconia) ; Dana. To detect the zirconia and lime the fine powder is dissolved in hydrochloric acid, silica separating, evaporated carefully until nearly dry, dissolved in water, nitric acid added to form sesqui- chloride of iron, and the solution filtered. A slight excess of ammonia being added to the filtrate, zirconia and sesquioxide of iron are precipitated, with a little lime. This precipitate is treated as described under wohlerite. The ammoniacal solution is tested for lime with oxalic acid and for manganese with sulphide of ammonium. The gelatinous silica separated by hydrochloric acid is not to be regarded as pure silica, since it contains, according to Rammelsberg, feome zirconia. (Erstedite, according to Forchhammer, behaves as follows: — In the matrass yields water. B. B. infusible. In borax and 162 plattker's blowpipe analysis. S. Ph. dissolves with diflBculty in the 0. F. to a colorless glass. With S. Ph. and tin on coal a titanic acid reaction is produced. Is not dissolved by soda. The zirconia can be detected by fusing the fine powder with eight times its weight of bisulphate of potassa in the platinum spoon, treating the powdered mass with water, filtering out the silica, and then diluting with much water. A few drops of nitric acid are now added and the titanic acid thrown down as thoroughly as possible by continued boiling. After settling this is filtered out and the filtrate tested further as under wohlerite and eudialyte. Zircon, according to Berzelius, behaves as follows: — The colorless, transparent variety is unaltered ; the clear, red {hyacinth) loses color, becoming clear as water, or very slightly yellow. The opaque, brown variety becomes white and resembles cracked glass. The dark variety from Finbo yields some moisture, becomes milk-white, and then appears as if weathered. All are perfectly infusible. In borax zircon dissolves with difficulty to a clear glass, and this can be flamed opaque if properly saturated. Not attacked by S. Ph., the glass remaining colorless in 0. P. and E. P. Insoluble in soda, the edges only being slightly aitacked and the soda going into the coal. On platinum foil most zircons show traces of manganese. Auerbachite behaves like zircon. Malacon, according to Scheerer, behaves as follows : — In the matrass yields some water. B. B. is infusible. The fine splinters become white and opaque in borax and S. Ph., but are not dissolved. The extremely fine powder dissolves slowly in borax, showing a little iron ; it is also decomposed by S. Ph., leaving the silica alone. In small fragments it is not attacked by soda. Catapleiite yields water in the matrass. B. B. fuses easily to a white enamel. In borax dissolves with difficulty to a clear, colorless glass. Easily soluble in hydrochloric acid without gelatinizing; the dilute acid solution colors turmeric paper orange-yellow (zircon reaction). Dana. To detect zirconia in zircon and the following minerals, their very fine powder is fused with one and a half volumes of soda and three of borax on coal in the 0. F., the clear bead pulverized, treated with hydrochloric acid, and very gently evaporated nearly to dryness, so as to separate the silica. Eapid evaporation at a high temperature would cause much zirconia to remain undissolved in the subsequent treatment. The nearly dry mass is treated with a sufficient quantity of water, and the silica filtered out, after which any protochloride of THoaiA. 163 iron must be transformed into sesquicliloride with nitric acid. The zirconia and sesqnioxide of iron are then thrown down by ammonia flnd the very voluminous precipitate concentrated, so that it may be filtered out more easily, by boiling the whole. The little yttria and lime in malacon are here to be disregarded. The separation of the sesqnioxide of iron from the zirconia is eflfected as before in case of wuhlerite and eudialyte, pp. 160 and 161. The ammoniacal filtrate can be further tested with oxalic acid, salt of phosphorus, and sul- phide of ammonium, for other constituents. Thoria, if present, would be found in the precipitate of sesqui- oxide of iron and zirconia, and would remain behind on digesting this in oxalic acid. 13. Thoeia, Th 0". Its occurrence in the mineral kingdom. Thoria is of very rare occurrence; it has been found in: ^schynite, 3,— Niobate and titauate of Th 0', (Ce, La, Di)' 0', Y" 0% Fe 0, Ca 0. Pyrochlore, vide lime; Samarskite, vide yttria. Thorite, III, 1 G,— Th 0', Si 0' + H' 0, with admixture of 2 (Ca, Fe) 0, Si 0'; it contains frequently uranium. Orangite, perhaps — 2 Th OS Si 0' + 3 H" 0, without the lime-iron silicate. Examination for Thoria. Including the blowpipe characteristics of the above minerals, SILICATE OF THOEIA. Tliorite behaves, according to Berzelius, as follows : — In the matrass yields water and turns brownish-red. B. B. on coal infusible. Dissolves easily in borax and the saturated glass is opaque on cooling, but if otherwise cannot be made opaque by flaming. The glass shows iron. With S. Ph. it leaves a silica skeleton ; the glass shows iron and opalesces in cooling. With soda on coal a yellowish-brown slag; on platinum foil manganese. By a reduction assay minute, malleable globules of tin and lead are obtained. Orangite, according to Bergmann, behaves thus : — In the platinum spoon small splinters generally crumble to a dark 164 plattner's blowpipe analysis. brown muss and again assume their orange color on cooling; the larger fragments become opaque. Heated in the, alcohol flame in the forceps fragments decrepitate slightly and particles which fly ofi" glow brightly, without afterward showing change of color. Infus- ible on coal, tlie edges only being sometimes slightly glazed, perhaps owing to foreign bodies. With soda only the silica is dissolred ; the remaiijing substances can be detected as yellowish particles in the opaque glassy mass with the magnifier. With borax a yellowish bead, colorless when cold ; but with S. Ph. in the 0. F. a r..'ddish glass, colorless on cooling, which becomes yellowish in the "^ ¥. and is then also colorless when cold. To detect the thoria in fhese minerals they are fused in fine powder, according to p. 94, with soda and borax on coal beside a silTer button in the E. F., until any oxides of tin and lead^are reduced and united with the silver and the fused glass appears quite clear. This is pulverized and treated as usual with hydrochloric acid ; the dry salt obtained by evaporation is moistened with hydrochloric acid, dissolved in water, and the silica filtered out. After boiling the solution with a few drops of nitric acid to peroxidize the iron, a slight excess of ammonia is added, which throws down thoria, Ecsqnioxides of iron and uranium, and part of the protoxide of manganese. The amount of alumina present is not worthy of notice. The washed precipitate, while moist, is dissolved in dilute sulphuric acid and the solution evaporated to a small volume. During the evaporation neutral sulphate of thoria separates as a white, loose mass, from which the acid solution of the (Jther bases is decanted after some time. This salt is then washed with boiling water, dried, and converted into pure thoria by ignition. To separate the thoria still contained in the wash-water and the solution of the other bases, the whole is evaporated to a rather small volume, neutralized with carbonate of soda, and then a boiling-hot saturated solution of sulphate of potassa is added. While cooling a double sulphate of thoria and potassa separates, which is washed with a cold, saturated solution of sulphate of potassa, and then dissolved in boiling-hot water containing some sulphuric acid, after which the thoria is precipitated by ammonia, dried, and ignited. The oxides of iron and urs'iium are separated from the solution as directed under yttria, p. 157. The lime is found in the first ammo- niacal filtrate by adding oxalic acid. CERIUM — LANTHANUM — DIDYMIUM. 165 2. Examinations for Metals or their Oxides. 1. Cekium, Ce ; Lanthanum, La ; Didymium, Di. Occurrence of these metals in the mineral kingdom. Cerium is one of the rare metals and occurs in the following minerals, almost always in connection with more or less lanthanum »nd didymium, a. Combined with _/?««on'Ke in : Fiuocerite ,— 2 R' F' + R' 0'; R = Ce, La, Di, Y; Hamartite,— (Ce, Lap F« + 2 (Ce, La)'' 0= 0' ; Yttrooerite, vide lime. i. With pJwsphnric acid in : Cryptolite,— (Ce, La, Di)^ 0', P' 0", and a little Fe 0. A mineral from Kararf vet, near Fahluu, belongs here, with the Ce as Ce 0', and also a few per cent of F, and a little Ca ; Monazite, 2,— R' 0', P'O'. R -. Ce, La; also a little CaO and Mn 0, as well as Sn 0'. Some specimens contain up to 18 per cent of Si O'^ and Th 0". c. With carbonic acid in : Parisite, 1, — carbonate and fluoride of Ce (La, Di) and calcium ; Lanthanite, 1,— La" 0^, 3 C 0» + 8 H» O. d. With various acids (tautalic, niobic, titanic) : Pyroohlore, vide lime ; Fergusonite, euxenite, polycrase, vide yttria. e. With silicic acid in : Cerite, III, 1 G,— 3 Ce' 0^ 3 Si 0' + H' 0. Ce partly replaced by La, Di, Ca, and Fe; Orthite (allanite, cerin, bucklandite, pyrorthite), I A, 1 G, hydrous silicate of Ce (La, Di)' C, AP 0', Fe' 0", Fe 0, with a little MgO, Na'O; Bodenite, muromontite, gadolinite, vide yttria. /. In silicates containing titanic acid : Tscheffkinite, I A, 1 G,— Si OS Ti 0, Ce (La, Di)" 0=, Fe" 0', Fe 0, Ca 0, with a little Zr"OS Y^OS MgO; Mosandrite, I A, 1, of similar composition, with less Ti 0", more Ca 0, and also H» and F. 166 plattxek's blowpipe an^alysis. Examination for Oerlum, Iianthanum, and Didymluma Including tlie blowpipe characteristics of the above named minerals. a. General examination for cerium, lanthanum, and didymium. The great diflBculty of completely separating the three oxides from one another renders it seldom possible to undertake this with the trifling quantity employed in blowpipe analysis. The oxide of cerium can be separated in approximate purity from the oxalates of the three earths, by converting them into nitrates, evaporating the solution of the nitrates to dryness and heating the residue until it becomes light yellow. When cold it is treated with boiling dilute nitric acid, which dissolves the oxides of lanthanum and didymium, and leaves cerium almost completely behind, as basic nitrate; and more completely by repeating the operation. From the solution of lanthanum and didymium the oxides are thrown down with ammo- nia and dissolved in sulphuric acid. The dry salt being then dis- solved to saturation in water at 5° to 6° C. and the solution warmed to 30°, sulphate of lanthanum separates, leaving the didymium salt in the solution, from which it can be precipitated by potassa. The oxides may be obtained still purer by repeating this process. Pure sesquioxide of cerium is white to bluish-gray. Dioxide, ob- tained by igniting the sesquioxide in the air, is white, with a shade of yellow, and is orange-red when heated. Oxide of lanthanum is colorless; ignited oxide of didymium is white and the peroxide brown. In many of the above-named minerals, containing besides oxides of cerium, lanthanum, and didymium, no considerable quantity of other coloring metallic oxides, y'iz. ,fluocerite, the phosj^hates and carbonates, and cerite, the oxides mentioned can be found with comparative ease. With borax and S. Ph. in the 0. F. red or dark yellow beads are obtained, according as more or less has been dis- solved, and these lose their color on cooling, as well as in the E. F., to such an extent that the S. Ph. bead becomes quite colorless, The borax bead can also be rendered opaque or enamel-white by flaming, and the more quickly the less silica there is in the mineral In the other minerals, which contain also oxides of iron and uranium, or titanic acid, the cerium, etc., cannot always be detected with certainty except by the aid of the wet ways, as has been already described for many of the above minerals under yttria. CERIUM — LAITTHANUM — DIDYMIUM. 167 5. Behavior of the above-named minerals "before the blowjiipe. FLUORIDES. Fluocerite in the matrass yields water and at the melting point of glass the matrass is attacked at a distance from the assay. The water colors Brazil-wood paper yellow; the assay piece becomes white. In the open tube, when the flame is directed within the tube, the interior is attacked; the condensed water turns Brazil- wood paper yellow, and the assay piece assumes a dark yellow color. On coal infusible, but darkens in color. With borax and S. Ph. reacts like oxide of cerium containing oxides of lanthanum and didymium. With soda it is disintegrated and swells, but is not dissolved ; the soda goes into the coal, leaving a gray mass. Fluocerine yields water and becomes darker (Berzelius). On ■coal changes color and when heated nearly to redness appears black, but on cooling becomes dark brown, then fine red, and finally dark yellow. This change of color distinguishes it from fluocerite. It ia infusible. PHOSPHATES. Gryptolite. The mineral first examined by Wohler, which re- mains on dissolving the green and red apatite of Arendal in dilute nitric acid, is infusible. A similar compound is obtained on dis- solving roasted cobaltite from Johannesberg, Sweden. According to Chapman, however, it fuses on the edges, and gives a flame reac- tion for phosphoric acid. Monazife. — B. B. becomes dark gray, and when strongly heated ;he crystal faces become lustrous. Moistened with sulphuric acid it gives a bluish-green flame. Dissolves in borax and S. Ph. to a glass, yellow when hot and nearly colorless when cold ; the same in both flames ; with borax in the E. F. the strongly saturated glass becomes enamel-white by flaming. With S. Ph. and tin on coal a slight titanium reaction. With soda on coal a little tin is obtained, and on platinum foil a manganese reaction. With boracic acid and iron phosphide of iron is formed. (Kersten.) CARBOKATES. Parisite in the matrass yields water and carbonic acid, becoming cinnamon brown and friable. B. B. phosphoresces, but is infusible. With borax a yellow bead, colorless on cooling (Bunsen). With fused S. Ph. in the open tube gives the fluorine reaction. (Dana.) 168 plattxer's blowpipe analysis, Lanthanite from Bethlehem, Penn., becomes white when heated, then brown, and is infusible. With borax a bluish glass, growing brown on cooling and finally amethyst-red. SILICATES. a. Cerite yields water and becomes quite opaque in the matrass. On coal springs about and is infusible. Dissolves slowly in borax, giving in 0. F. a deep, dark yellow glass, becoming lighter on coolings and which can be flamed opaque. In E. F. the glass shows a feeble iron color. By S. Ph. the oxide of cerium is extracted with the usual play of colors ; the glass appears colorless when cold and a white, opaque silica skeleton remains. Undissolved by soda, but half fused to a dark yellow slaggy mass. (Berzelius.) b, Allanite (cerine from Bastiias) yields in the matrass some water without changing its appearance ; the water is not therefore chem- ically combined. B. B. fuses easily with intumescence to a black, lustrous, vitreous bead. Dissolves easily in borax to a black, opaque glass, which becomes blood-red, however, in 0. P. while hot, and moi-e or less dark yellow after cooling ; in K. F. it assumes a'fine, iron-green color. Does not become opaque by flaming. S. Ph. decomposes it, leaving a silica skeleton. The glass shows the iron color while hot, but in cooling becomes colorless and opalescent. (Berzelius.) Dissolves with soda to a black glass. Damour and Descloizeaux {Ann. de Chim. et de Pliys. LIX., 365) have tested allanite from various sources. That from Bastnils yields no water and fuses quietly to a black, magnetic glass. That from HitteriJe yields some water and is easily fusible, with formation of bubbles, but without intumescence, to a black magnetic enamel. Various allanites from Greenland yield a little water in the matrass, swelling much at the same time, and forming a spongy, gray mass, which heated a short time B. B. is converted into a black magnetic glass. c. Orthite from Finbo and Gottliebsgang, as well as from granite near Stockholm and Soderkoping, yields water in the matrass and becomes lighter in color at a higher heat. On coal intumesces, becomes yellowish-brown, and finally fuses with ebullition to a black, blebby glass. Dissolves readily in borax to a glass, blood-red in 0. F. and yellow when cold. In E. P. green. Is easily decomposed by S. Ph. with the usual phenomena- With a very little soda fuses; with more swells to a grayish-yellow slag. On platinum shows manganese. (Berzelius.) According to Damour and Descloizeaux (1. c.) orthite from CERIUM — LANTHAlfUM— DIDYMIJUM. 169 Snarum yields water and fuses with difficulty to a black, magnetic elag; similar reactions are shown by various orthites from Hitteroe,. some of which assume a gray color in the matrass ; by the uralor- thite from Miask, as well as orthites from Stockholm (one variety fuses to a grayish, blebby, feebly magnetic enamel) and Arendal. Orthite from Fahluu becomes white B. B. and fuses on the edges to a white enamel. 0. from Greenland yields some water, intumeaces strongly, and forms a gray mass, which fuses, in one variety, to a grayish-black, very slightly magnetic enamel; in the other, to a brownish-gray scoria, and in K. F. to a black magnetic enamel. d. PyrortMte (containing one-third its weight of carbon) behaves, according to Berzelius, as follows : — In the matrass yields very much water, the last portions being yellowish and having a burnt odor. The residue is as black as coal. Gently heated on coal and afterward ignited at one point, it takes fire and glows of itself. The combustion is more lively with several fragments, or with coarse powder, and when blown upon. It leaves the mineral white, or grayish- white, sometimes inclining to red, and so light and porous that it will not remain on the coal before the blowpipe flame. In the foiceps it fuses with difficulty to a black bead with a dull surface. With borax and soda like orthite. Dis- solves with difficulty in S. Ph., the porous mass remaining on the surface of the fluid bead, l^ut sinking into it on cooling. It emerges again on being re-heated. With soda behaves like orthite. To detect the separate elements in the foregoing silicates a proper amount of the fine powder is treated with aqua regia in a porcelain vessel, evaporated to dryness, dissolved in water, and the silica filtered out. Ammonia added in slight excess to the filtrate throws down Fe" 0', Ce" 0', La' 0', Di' 0', and Ar 0=; leaving most of the CaO, Mg 0, and Mn 0. By digesting the washed precipitate after filtering with a solution of potassa AF 0' is separated and can be obtained from the alkalice solution as directed for silicates under alumina. The oxides freed from AF 0' are treated while moist with not too concentrated a solution of oxalic acid and warmed ; this dissolves the iron, and the other oxides settle to the bottom in combination with oxalic acid, as a heavy crystalline powder. These salts are filtered out, washed with cold water, and ignited in the platinum capsule. The separation of the three oxides has been described on p. 166. After adding a little nitric acid to the filtrate the oxide of iron can be thrown down with potassa and tested B. B. with borax. The further treatment of the lime, etc., has been given under the earths. ITO plattxer's blo-vvpipe analysis. SILICATES CONTAINIlfG TITANIC ACID. Tscheffkinite behaves, according to G. Eose, as follows :— In the matrass swells and yields a little water. B. B. glows at first, then intumesces strongly, becomes brown and finally fuses to a black bead. Its powder dissolves rather easily in borax to a clear ^lass, slightly colored by iron ; a small quantity yields a perfectly clear glass. In S. Ph. the same, but dissolves more slowly, and when much is added silica separates and the bead opalesces on cooling. Puses with soda, but soon spreads out and sinks into the coal. By washing away the coal a few spangles of iron are obtained. On platinum shows manganese. Mosandrite. — This mineral, which occurs with leucophanite, haa been described by Erdmann. In the matrass' it yields much water and turns brownish-yellow when heated to redness. B. B. iusea «a8ily with intumescence to a brownish-green, semi-lustrous bead. With borax dissolves easily to an amethyst-red bead, yellowish and nearly colorless in K. E. With S. Ph. gives a silica skeleton and in the E. F. the titanium reaction. With soda on platinum foil shows manganese. To determine such constituents of these two silicates «s cannot be detected in the dry way, their fine powder is digested at a very gentle heat with hydrochloric acid, until it is thoroughly decomposed, when it is diluted with water and the silica filtered out. This may be tested B. B. as tx) purity, after being washed. The filtrate is heated to boiling and nitric acid added to form sesqui- chloride of iron, and as some titanic acid is liable to separate, it is filtered out and a slight excess of ammonia added to the filtrate, Ce"0', La' OSDi" 0', Fe' 0', and Ti 0' are thrown down, leaving Ca 0, Mg 0, Mn in solution. The precipitate is filtered out, washed with cold water, and treated with a dilute solution of oxalicacid,which dissolves out Fe' 0' and Ti 0% leaving Ce' 0', La'' 0', and Di' 0' as oxalates. The former are precipitated by potassa and separated by dissolving them in a little dilute sulphuric acid, adding a few drops of nitric acid, diluting with much water, and boiling until as much titanic acid is precipitated as possible. This separation is really unnecessary as the presence of titanic acid and iron can be detected with certainty in the potassa precipi- tate by means of borax and S. Ph., vide titanic acid. The undissolved oxalates are ignited and treated ad before, p. Iti'J, and the bases in the ammoniacal solution are also separated by the methods previously made known. MANGANESE. 171 2. Manganese, Mn. Its occHrre7ice in the mineral Icingdom and in metallurgical products. Manganese forms an essential constituent of several minerals, differing considerably in chemical composition; it is found in the following combinations: fl. With arsenic in Kaneite, — Mn^ As. I. With sulphur in Alabandite (mangan blende), — Mn S; Hauerite, — Mn S^ c. As oxide, either /r«e, or combined with water of hydration in Hausmannite (black manganese), Mn' 0', sometimes containing a little Ba 0, Si 0\ and H= 0. Braunite,— Mn' 0^ and often Ba 0, Si 0", and H" 0; Manganite,— Mn' 0= + ff O ; Psilomelane, — a compound of Mu 0' with Mn 0, Ba 0, K" 0, and H' ; also sometimes Co 0, Cu 0, Li' 0. In the variety con- taining Li' (so-called lithiophorite) are also Al' 0' and Fe' 0=; Wad (groroilite), probably a decomposition residue of various man- ganese ores. It consists especially of Mn 0", Mn 0, and H' 0, but generally contains more or less of other bodies, especially Fe' 0', Ba 0, AP 0=, Si 0', etc. ; Polianite,— Mn 0', with a very little A? 0', Fe' 0% and IP 0; Pyrolusite, — Mn 0', often containing a little Ba and H' 0; also Tl and V; Varvioite,— Mn' 0' + 2 Mu 0' + H» O ; Pyroohroite,— Mn + H' 0, and some Mg O, Ca 0, and C 0». d. Combined with other metallic oxides : • a. With protoxide of cobalt in Asbolite (earthy cobalt), — Mn 0', CoO, Cu 0, H'O; sometimes mixed with Fe' 0', Co" As' 0', and silicates of alumina; that from Canisdorf contains 19.4 per cent. Co; Eabdionite,— Mn' O', MnO, Fe' 0', Cu 0, Co O, H' 0. /J. With oxides of zi7iG and iron in Franklinite,-(Zn, Fe, Mn) + (Fe, Mn)' 0'. y. With oxide of copper in Crednerite,— 3 Cu + 2 Mn' 0', and some Ba O and Ca O. Cu = 33.7 per cent. I^mpadlte (cupreous manganese),— (Cu, Mn) 0, 2 MnO' + 3 H' 0, and a, UttleCoO, Oa O, Ba 0, Mg 0, K' ; about 12 per cent. Cu. 173 FLATTJSTEE'S BLOWPIPE ANALYSIS. e. Combined with acids : a. With sulphuric acid in Apjohnite (manganese alum),— Mn 0, AP 0', 4 8 O' + 24 H> 0. /?. With phosphoric acid in Hureaulite,— 5 Mn 0, 3 P' 0' + 5 H' 0; part of the Mn replaced byFeO; Heterosite, similar to hureaulite, but containing Mn' 0', Fe' 0' ; Triplite,— Mn 0, 3 Fe 0, P" 0' + Mn F^; zwieselite is similar. Triphylite, tetraphylin, vide lithia. y. With loracic acid in Sussexite,— 2 Mn 0, B' 0' + H' 0. Mg O replaces some Mn O. 6. With carbonic acid in Ehodochrosite (dialogite), — Mn C 0'; generally some Mn replaced by Fe 0, Ca 0, and Mg 0. Mangano-calcite is similar. e. With tnngstic acid in Huebnerite, — Mn W 0*, with 33.1 per cent. Mn 0; Wolframite, vide iron. C. With titanic acid in Pyrophanite,— Mn O, Ti 0', with some Si 0' and Fe O. rj. With antimonic acid in Haematostibiite,— 7 Mn O, Fe 0, Sb' 0' ; ferrostibian, containing H' O, is similar. ^. With arsenic acid in Chondrarsenlte, xantharsenite, hemaflbrite (aimafibrit), — 6 K O, As' 0' + 3 - 6 H' ; R chiefly Mn O, with a little Ca and Mg O. 1. With tantalic and niobic acids in Tantalite and oolumbite, vide iron. K. With silicic acid in Ehodonite (bustamite, palsbergite), I, 3, — Mn 0, Si 0' prevailing, with a little Fe 0, Ca 0, and Mg 0. Cummingtonite is similar. Fowlerite is a zinciferous rhodonite with 5 per cent. Zn 0. Tephroite, I-II, 1 G, — the variety from Sparta, N. J., essentially 3 Mn 0, Si 0^ with very little Fe 0. In other varieties the corresponding magnesia silicate is present. The reported zinc present is said to arise from a mixture of zincite; Knebelite, III, 1 G,— 2 Fe O, Si 0' + 2 Mn O, Si 0' ; Manganese, black silicate {Mangankiesel, schwarzer), I A, — Mn' 0', 3 Si 0' + 3 H' ; with a little Fe' 0', Al' 0', Mg O, Ca 0. Stratopeite, neotocite, wittinglte, are similar. Klipsteinite,— 3 Mn 0, 2 Mn' 0», 3 Si 0' + 4 H' 0, with some Fe' 0', Al' 0», Mg (homogeneous ?) ; Helvite, vidp Rlucina; Carpholite, ride alumina; Troostite, vide zinc. EXAIIINATIOK FOR MANGANESE. 173 The numerous other silicates containing manganese have been already partly enumerated under the alkalies and earths, and the remainder will be mentioned under the following metals, etc. Manganese also forms a frequent constituent of various metallur- gical products, occurring in the metallic state in raw iron and stetl ; with sulphur in the vai-ious matt-like products from the smelting of •certain silver, lead, and copper ores, and especially also as protoxide ■with silicic acid in the different slags. Examination for Manganese Jncluding the blowpipe characteristics of the minerals above enu' merated. a. General examination for manganese. Manganese can be very easily detected in substances containing, besides oxide of manganese, no other metallic oxides which give ■colored glasses with borax and S. Ph., by simply dissolving them in those fluxes on platinum wire in the 0. P. and then treating the bead with the E. P. The hot beads appear amethyst-red, but on ■cooling are red inclining to violet, and lose their color when treated foi some lime in the E. F., especially on coal. S. Ph. is far less intensely colored than borax and the color disappears much more readily in the E. P., in this flux also. Should a small proportion ■of other coloring oxides be present they alter the amethyst color obtained in 0. P. slightly or not at all, but occasionally show their own peculiar color after the manganese coloration has disappeared under the E. P., e. g., sesquioxide of iron. Should the amount of fiesquioxide of iron be large, the bead appears blood-red in the 0. F. and yellow after short treatment in the E. P. When the amount of Oxides and manganese is considerable the assay should be quickly Salts. pinched together a little after the reduction, or else shaken ofi' from the wire, so that it may cool immediately and not give the protoxide of manganese an opportunity to color the bead again by becoming more highly oxidized. If there is not manganese enough to color the S. Ph. bead, the latter, after a sufficient quantity of the substance has been dissolved in it, is brought in contact with a little crystal of nitre, which causes it to froth up and assume on cooling an amethyst, or feeble rose color, according to the amount of man- ganese present. The small fragment of nitre is placed near by on a porcelain dish, and the bead after being strongly heated on the wire in the 0. P. is quickly brought against it, when the two salts unite 174 plattxek's blowpipe analysis. and permanganate of potassa is formed by the resulting oxidation. The evolution of gas causes the glass to froth up, and it may show the red color only when cold. On treating it again in the flame the reaction produced by the nitre entirely disappears. Another method must be employed to detect manganese in com- pounds containing more than a small proportion of distinctly coloring oxides. The best reagent is soda, which in all cases gives the most characteristic reaction for manganese. If there is not less than 0. 1 per cent, of oxide of manganese present the powdered substance is mingled with two or three volumes of soda and fused on platinum foil in the 0. F. The oxide of manganese dissolves in the soda to a transparent, green mass, consisting of manganate of soda, which flows around the undissolved portion and on cooling is distinctly bluish-green. If there is less than 0. 1 per cent, of manganese this green color is not so easily obtained, but by employing two parts of soda and one of nitre all of the oxide of manganese is more highly oxidized and the least trace of it colors the soda distinctly bluish- green, after the assay is perfectly cold. To obtain a certain manganese reaction from garnets, Fischer (Leonh. Jaliri. 1861, 653) has recommended to dissolve not too little of the mineral in a borax bead and then to fuse this with soda on platinum foil, when the manganese reaction is more distinct tlian with soda alone. (Chapman proposed this method for limestone, etc., as early as 1852.— Transl.) The presence of sesquioxide of chromium gives rise to yellow alkaline chromates when soda and nitre are used, but this in no way conceals the green color of the alkaline manganate, since when 3XJde of chromium is fused on platinum foil with equal parts of soda and nitre a very trifling quantity of manganese may be detected by the green color of the perfectly cold, fused mass. This green is^ however, no longer bluish, but yellowish-green. Minerals containing any oxide of manganese, higher than the protoxide, evolve chlorine when heated with hydrochloric acid, and this can be detected by its odor.* Metallic compounds must be dissolved in nitric acid, evaporated to dryness, the salts decomposed by ignition, and the resulting oxides, tested for manganese with soda and nitr^, as above. Meuiuc Areenide* If the substance consists of, or contains sulphides *'"' saipWdcB. * Traces of manganese can be detected by fusing not too little potassium chlorat.j in a matrass and adding a little of the substant^e to be tested, when the rose color of the cooled mass shows manganese with certainty. (Boettger.) MAKGANESE — ARSENIDE — SULPHIDE — OXIDES. 175 or arsenides of the metals, it must be roasted on coal, p. 78, before' the above tests for manganese can be applied. When the substance contains silica and protoxide of cobalt at the same time, e. g., an ore dressed in the large "'""'"^ °'^' way, the above treatment with soda yields a blue mass, consisting of oxide of cobalt dissolved in silicate of soda, by which the green of the manganese is entirely concealed. After separating the silica and other injurious ingredients, however, by fusion with soda and borax and subsequent treatment in the wet way, as directed for silicates under lime, p. 128, the manganese can be found with certainty. h. Blowpipe characteristics of the minerals enumerated aiove. AESENIDE OF MANGANESE. Kaneite burns on coal with a blue flame and yields a coat of arsenous acid (Kane). The residue undoubtedly gives manganese reactions. SULPHIDE OP MANGANESE. a. Alaiandite is unchanged in the closed tube. In the open tube yields sulphurous acid and turns grayish-green on the surface. When thoroughly roasted on coal, which occurs very slowly, it reacts like pure oxide of manganese. Very slightly fusible on the edges. b. Hauerite yields sulphur in the closed tube and becomes green. In the open tube yields much sulphurous acid and becomes green on the surface. When well roasted reacts like oxide of manganese with the fluxes. OXIDES OF MANGANESE. Most of the oxides, viz., hausmannite, braunite, manganite, vsilomelnne, varvicite, and wad yield more or less water in the matrass, and such as contain a higher proportion of oxygen, espe- cially ^f'^iff;?2Ve,j»«/ro^2(SiYe, and groroilite, when heated to redness give off oxygen, which may be recognized by means of a little fragment of charcoal placed in the matrass. They dissolve in borax and S. Ph., some of them with efferves- cence, produced by escaping oxygen, and either behave like pure oxide of manganese, or after reduction show iron, p. 173. They frequently contain a small amount of alkalies, baryta, or lime, which may be detected by igniting them thoroughly in the 0. F., laying them on platinum foil, moistening them with a few drops of water, and after some time testing this water with red litmus paper. On, . 176 PLATTXER'S blowpipe AITALYSIS. dissolving such an oxide of manganese in hydrochloric acid chlorine is evolved and any silica present remains behind. The solution may then be further examined as directed under baryta and lime. Pyrochroite yields much water in the matrass, becomes green, then greenish-gray, and finally brownish-black. Dissolves in hydro- chloric acid, giving carbon dioxide. Litliiopliorite gives a distinct lithium flame, the tip of it sometimes colored green by copper. OXIDES OF MANGANESE COMBINED WITH OTHER METALLIC OXIDES. Black earthy cobalt from Saalfeld yields water, which has a burnt odor. B. B. in the forceps and on coal is infusible; frequently it colors the flame green from copper, and on coal evolves a feeble odor of arsenic. With borax in 0. F. a dark violet glass, smalt- blue in R. F. In S. Ph. only the cobalt color, but the saturated bead treated on coal with tin becomes opaque-red on cooling, vide copper. Is not dissolved by soda, but gives a strong manganese reaction with soda and nitre. The same mineral from Schneeberg yields water in the matrass. With borax and soda like the above ; but with S. Ph. shows only the cobalt reaction. Many so-called earthy cobalts contain so little Co and so much Mn that a very large amount must be dissolved in the borax bead and this treated for a long time in a good R. F. in order to produce a blue color. Babdionite yields water, fuses on coal to a gray magnetic button; with the glass fluxes shows especially cobalt; with soda and nitre a strong manganese reaction. Franklinite alone is infusible ; the moistened powder treated some time on coal in a strong R. F. yields a very distinct zinc coat. With borax and S. Ph. shows manganese; but the somewhat strongly saturated borax bead is rather red, and on coal in the R. F. becomes bottle-green from proto-sesquioxide of iron. With soda on platinum foil shows manganese, and on coal a slight zinc coat, becoming stronger when some borax is added. Crednerite fuses only on the edges of very thin scales. With borax a dark violet glass ; with S. Ph. a green glass, blue when cold, and becoming copper-red in R. F. Dissolves to a green solution in hydrochloric acid, with evolution of clilorine. (Rammelsberg.) Lampadite or cupreous manganese yields much water in the matrass and then decrepitates somewhat. In R. F. on coal becomes brown, but is infusible. With the fluxes afibrds reactions for coppei MAHTGANESB — COMBINATIONS WITH ACIDS — SILICATES. 177 and manganese, and with soda and borax in R. F. on coal yields a little button of copper. COMBINATIONS OF PROTOXIDE OF MANGANESE WITH ACIDS. Tbe phosphates of manganese, including hureaulUe, tripUie, twieselite, lieterosite, and tripliylite, yield more or less water. B. R fuse very easily to a globule and color the flame. Those free from lithia give a bluish-green, phosphoric acid flame ; the others produce a red coloration at the same time. With the fluxes react for man- ganese and iron. Huebnerite. — In the forceps less fusible than wolframite ; with the fluxes gives manganese and tungstic acid reactions. (Dana.) Rhodochrosite and manganocalcite occasionally yield some water and often decrepitate very violently. Thoroughly ignited on coal and moistened with water, they generally have an alkaline reaction on red litmus paper, owing to the presence of lime. They dissolve in the fluxes with efiervescence, owing to escaping carbonic acid, and react like oxide of manganese containing iron- Sussexite behaves, according to Brush, as follows : — In the closed tube darkens slightly and yields water, containing at least a trace of boracic acid. Fuses in the candle flame. B. B. in O. F yields a black crystalline mass, a.nd colors the flame intensely yellowish -green. With the fluxes afibrds the manganese reactions. SILICATES. Part of the silicates enumerated on p. 173, yield some water in the matrass, which occasionally has a burnt odor. Their fusibility is indicated by the annexed figures. With borax dissolve easily to a clear glass, showing manganese and more or less iron. With S. Ph. yield a silica skeleton and a manganese glass, generally colorless in the R F., but sometimes opalescent on cooling. They fuse with little soda to a black bead, with more yield a diflBcultly fusible slag, and an excess of soda goes into the coal. When it is necessary to determine any earthy admixtures the method described for silicates under lime, p. 138, is followed. 178 plattnek's blowpipe analysis. 3. Iron, Fe. Its occurrence in the mineral kingdom and in 7netallurgical products. Iron is very widely spread throughout nature, occurring in most minerals, although sometimes only in traces. It is found under various conditions in the following minerals: a. Metallic, as Native iron, — Fe, in grains and scales, frequently containing carbon (graphite) ; Meteoric iron, — Fe, with more or less Ni and small quantities of Co, Mn, Cu, Or, Sn, Mg, Si, C, CI, S, and P; Iron-platinum (Eisenplatin), vide platinum. b. Combined with arsenic in Leucopyrite, — Fe As" (with 27.2 Fe), but other atomic proportions occur: Fe'As', etc.; some sulphur almost always present (0.7-6 per cent.), which possibly in part belongs to admixture of arsenopyrite; sometimes some Sb, Co, and Cu (glaucopyrite). c. Combined with arsenic and sulphur in Arsenopyrite (mispickel), — Fe S" + Fe As", with 34.3 per cent. Fe; in danaite and Kolaltarsenhies (part), belonging here, some of the Fe is replaced by Co (6.4 per cent, in the former, and in the latter from 6.4 to 18.6 per cent.) ; Glaucodot, vide cobalt. d. Combined with sulphur in Pyrrhotite {magnetic pyrites), — Fe" S" + ^* Most varieties con- tain a little nickel; Pyrite, — Fe S' with 46.6 per cent. Fe; often with a little As, traces of gold, and sometimes thallium; Marcaslte {radiated, spear, etc., pyrites), — Fe S^ in orthorhombic form ; Lonchldite, — Fe S', with 1.4 per cent. As, perhaps an isomorphous mixture of the two preceding; Kyrosite, probably raarcasite containing some Cu and As. The various sulphides of iron also form more or less essential constituents of many minerals, which will be mentioned under Co, Ni, Zn, Sn, Cu, Ag, and 8b. e. As oxide, frequently with water of hydration, in Magnetite,— Fe 0, Fe' 0', with 72.4 per cent. Fe, often with a little Mn and Si 0'; * Fe S occurs only disseminated in meteoric iron, and has been called troilite by Haidinger. IKOK. 179 Hematite {red iron ore, specular iron), — Fe' 0', with 70 Fe, and sometimes a little Cr or Ti; Turgite,— 2 Fe' 0' + H" 0, with 66.3 Fe ; Gothite (needle-ironstone, pyrrhosiderite), — Fe' 0" + H" 0, with 63.9 Fe, and mostly containing some Mu" 0' and Si 0' ; similar are lepidocrocite and stilpnosiderite (which contains some Limonite {brown iron ore), — 2 Fe" 0" -\- oW 0, with 59.9 Fe, some- times Si 0', Mn' 0', Al" 0=, as well as F 0' and traces of Cu and Co 0; Xanthosiderite {ijelloiu ochre),— Fe' 0^ + 2 ir 0, with 57.1 Fe, besides Si 0", Al' 0=, Mn= 0=, Ca C 0^ and Mg C 0'; Clay-ironstone, a mixture ol limonite and clay; here belong the shelly yellow clay- ironstone (Hisenniere), and the granular yellow clay-ironstone pisolitic ore (Bohnerz); Bog ore (^Saseneisenstein, Sumpferz, Quellerz), ferric hydrate with Mn' O', quartz sand and admixtures ot phosphate, silicate and organic salts {humic acid} of • Fe' 03 and Fe O ; OchrOj^deposited from chalybeate springs and essentially Fe' 0' -l-nH' 0, but con- taining small quantities of other metallic o^des and earths. /. As oxide, with other oxides in Magnesioferrite,— Mg 0, Fe' 0', with 56 Fe ; Hercynite,— Fe 0, AP 0', with 27.7 Fe; a little Fe replaced by MgO; Jaoobsite,— (Mn, Mg) + (Fe, Mn)' O', with 4.2 per cent. Mn' O' and 6.4 Mg j Plumboferrite,— (Pb, Fe) O, Fe' 0'; Franltlinite, vide manganese; Chromite (chromic iron) — (Fe, Mg, Cr) -f (Cr, Al, Fe)' 0' ; here belong 2}icotite (8 per cent. Al' 0^), and chrompicotite. g. Combined with acids : a. With sulphuric acid in Melanterite {copperas),— Fe S 0* -f 7 H' 0; 25.9 Fe 0; Pisanite,— (Cu, Fe) S 0* + 7 H= 0; 11 per cent. Fe 0; Eoemerite, ferric and ferrous sulphate, a little Zn and 28 per cent, water. Botry- ogen contains, besides the oxides of iron, magnesia, while voltaite contains a few per cent, of K' O and Al' 0» ; Halotrichite,— Fe O, AP 0», 4 S 0' + 24 H' 0, with a little Mg and K' ; Glookerite, apatelite, raimondite, misy (perhaps only a variety of copiapite, Nau- mann-Zirkel), ttbroferrite, all hydrous ferric sulphates of varying composition ; Copiapite,— 2 Fe' 0=, 5 S 0' -f- 13 H' 0, and a little A? 0^ Ca 0, Mg 0, Si 0'; CJoquimbite, — Fe' 0', 3 S 0' -f- 9 H' 0, and often some gypsum and epsomite intermixed; 180 plattxer's blowpipe analysis. Jarosite, vide potassa ; Gelbeisenerz, vide potassa and soda ; pissophanite — the brown Tariety very nearly 2 Fe^ 0', S O' + 15 H^ O— in the green variety much Fe' 03 is replaced by AP OK /?. ^'ith phospJioiic acid in Dufrenite (kraurite) — 3 Fe' 0% P' 0' + 3 H' 0, but mostly with some ferrous phosphate; Strengite — Fe'' 0% P= 0' + 4 H' 0; Vivianite, — 3 Fe 0, P° 0' + 8 H° ; with varying amounts of ferric phosphate in the colored varieties; Delvauxite,— Ca 0, 2 Fe' 0', P^ O' + 8 W 0. In ealcioferrite, belonging here, i» more Ca ; Pseudotriplite,— 3 (Fe, Jtn)' O', 2 P' 0* + 2 H^ 0, a deoompoaition product of tri- pbylite. AUuaudite belongs here, a phosphate rich in Mn and containing alkali also ; Cacoxenite,— 2 Fe' 0', P'' 0' + 12 H' 0, with admixture of Si 0', Ca 0, Mg 0, AF 0', and some F; Childrenite,— 6 Pe 0, 2 Mn 0, 2 Al» O', 3 P" O', 4 H' O; Andrewsite, chalcosiderite— contain Fe» O', Fe O, Cu 0, Mn O, AP 0», F" 0=, and a little As2 0' ; Diadochite — 5 Fe' 0', 4 S 0% 2 P' 0' + 32 H' 0; Beudantite — 2 Pb 0, 4 Fe' 0% 3 S 0=, FO* +H'0; some P' 0' almost always replaced by As' 0'; Triphylite, tetraphylin, vide lithia; Heterosite, triplite, hureaulite, vide manganese. y. With carlonic acid in Siderite {spathic iron), — Fe C 0", with 48.2 Fe, but generally con- taining more or less Mn 0, Ca 0, Mg 0. 8. With oxalic acid in Humboldtine (oxalite),— 2 Fe C 0* + 3 H' 0. e. With loracic acid in Lagonite,— Fe' O', 3 B= O' + 3 H' O; Ludwigite,— Fe 0, 3-5 Mg 0, Fe' 0', B' O'j C. With arsenic acid in Arseniosiderite,— 6 Ca 0, 4 Fe' 0', 6 As' 0', 9 H' 0; Pharmacosiderite — 4 Fe' 0', 3 As' 0', 15 H' 0; Scorodite,— Pe' 0% As' 0' + 4 H' 0; Carminite,— 3 Pb 0, As' O' + 5 Fe' 0», As' 0>; Symplesite,— 3 Fe O, As' 0» + 9 H' O; Pitticite, Eisensinler (part), Arseneisensinter, are mixtures of hydrous basic iron sulphates and arsenates in varying propor- tions. IRON. 181 77. With tungstic acid in Wolframite, — isomorphous mixtures of Mn WO' and Fe W 0*; in ferberite, richest in iron, the Mn sinks to 3 per cent. ^. With titanic acid in Menaccanite {titanic iron), according to Mosander and Eammels- berg, the general formula is Fe Ti 0' -f x¥e' 0% with the value of X varying between and 5; a little of the Fe is almost always replaced by Mg and frequently by Mn 0. The varieties from Hofgastein (kibdelophane) and Bourg d'Oisans (criclitonite) correspond very nearly to the formula Fe Ti 0= (52.6 Ti 0^ and 47.4 Fe O ; then follow those from Krageroe and Egersund, Miask {ilmenite), Iserwlese (^iserite), Eisenach, Aschaff^nburg, Snarum, 5innenthal ; and lastly the so-called Eisenrose (basanomelan) of St. Gothard with only 8-9 per cent. Ti O^ to 84 Fe" O'. t. With tantahc acid in Tantalite, essentially Fe Ta" 0', with more or less Mn Fe'' 0*; some- times a not unimportant part of Ta^ 0' replaced by 'S\f 0'. Tantalites often contain also some Sn 0% and occasionally a little Ca and Cu 0. K. With niobic acid in Columbite (nioMte), — Fe Nb' 0', but this normal composition is rare (Greenland) ; Fe is almost always partly replaced by Mn 0, and an important part of the Nb" 0° by IV 0'. In certain varieties a little W 0' and Sn 0'. A. With silicic acid: Less important silicates are Ckamoisite, I, 1 G ; Cronstedtite, II, 1 G ; Thuringite (owenite), I-II, 1 G; (metachlorite) Hisingerite (thraulite), II-III, 1 ; (gillingite, degeroite) Stilpnomelane, I, 1; Nontronite, III, 1-2; (chloropal, unghvarite) Gelberde, part. III, 2 ; Umbra (hypoxanthite) III, 3 ; Pinguite, II, 1; (gramenite); ChlorophsBite, I ; Celadonite (Qrunerde) I, 3; Glauoonite, II, 1 ; Xylotile (Bergholz), 1, 1; Sordavalite, I, 2 ; Grunerite,— Fe O, Si 0», incl. a little Ca 0, Mg 0, Al» 0' ; Stirllngite, II, 1 G,— 2 (Fe, Mn, Zn, Mg) 0, Si 0^ Fayalite, I, 2,-2 Fe 0, Si 0', with little Mn, Mg, Ca, Al, Cu, and Pb; Anthosiderite, II, 1,-2 Fe2 0=, 9 Si 0"-|-2 H^ 0. All contain, besides Si OS Fe and Fe= 0=, also H2 O, and frequently some kV 0», Ca 0, Mg 0; rarely alkalies. 182 PLATTiTEK'S BLOWPIPE ANALYSIS. Almaudite (iron-alumina garnet), I, 2, — 3 Fe 0, Al' 0', 3 Si 0' as chief constituent, with more or less Ca 0, Mg 0, Mn 0, Fe' 0'; Pyrosmalite, I, 1 (in nitric acid) ; hydrated ferrous and manganous silicate, with Fe GV, or Mn G\\ Friedelite, of similar composition, but almost free from iron. Iron is found under various conditions in the products obtained by smelting ores : a. Metallic in Raw iron and steel, in combination with more or less C and a little S, P, Si, Mn, Al, Ca, Mg, etc. ; Bears {Eisensauen), which sometimes form in the shaft furnacea when smelting iron, copper, tin, and lead ores, owing either to some mistake in charging or to other causes, and which usually consist of a mixture of iron (carburet, siliciuret) and other metals, but very frequently contain an admixture of metallic sulphides and arsenides. Blach copper produced on the large scale, containing Cu as the chief ingredient, with more or less Pb, Ni, Co, As, Zn, Mo, Sb, Ag, is seldom free from Fe. Finally, a little iron is found in unrefined tin, lead, and zinc. t. Combined with arsenic in the various speisses produced in smelting lead, silver, and copper ores containing Fe, Ni, and Co combined with As. The speisses vary greatly in composition, but generally consist of (Fe, Ni, Co)' As, and more rarely of E° As, with very variable proportions of the basic metals, and mixed, or com- bined, with more or less Fe S, Pb S, Cu' S, Ag' S. c. Combined with sulphur in the various matt-like products from tlie smelting of gold, silver, lead, and copper ores, viz., in RoUstein, (Fe' S)", Fe S; In lead matt,—{Fe' S, Pb S, Cu' S)", Fe S; In copper matt, consisting of Cu' S, Fe' S, Fe S, in varying pro- portions, or combined with other metallic sulphides and arsenides, Pb S, Co S, Ni S, Zn S, Ag' S, Sb' S'. The same is true of other similar products (Leche, etc.). Here belong also the scaffolding, tutty or cadmia, formed in the furnace by sublimation, as: Rohofenbruch, consisting chiefly of Zn S, but often combined with more or less FeS, Pb S, and a little of other sulphides; Cadmia from lead furnaces (BleiofenbrucJi), the chief constituent being Pb S, which often contains some Fe S, Zn S, Sb' S', Ag'S. EXAMINATION FOR IRON. 183 d. A.S protoxide with silica in the various slags. «. As proio-sesquiozide in hammer-scales, forge-scales, etc. f. As protoxide with sulphuric acid in copperas or green vitrioL Examination for Iron, Including the blotopipe characteristics of the minerals and metallur' gical products above named. a. Examination for iron in general. This is very easy, since iron in combination with oxygen imparts a characteristic color to borax and S. Ph. and cannot be separated from these fluxes in the metallic state by the blowpipe flame alone. It is only necessary to consider whether the substances treated are com- pounds of metals, or are metallic arsenides or sulphides, or finally metallic oxides. If they are alloys consisting only of difficultly fusible metals, °^''' they are fused beside borax on coal in 0. F., until the glass is sufficiently colored with the oxides of the easily oxidizable metals. Should' lead, tin, bismuth, antimony, or zinc, be present, however, and the compound be easily fusible, the E. F. is employed, and is directed chiefly upon the glass, in order not to oxidize and dissolve too much of these metals. In both cases the still soft glass is removed from the metallic button and treated in K. F. on another spot, when the easily reducible metals are separated, leaving the borax colored bottle-green by proto-sesquioxide of iron, provided oxide of cobalt does not prevent this reaction. If the compound contained tin, or the green glass is treated for a moment in E. F. with a bit of tin on a fresh spot of the coal, all the iron is reduced to protoxide and appears pure vitriol-green. Should it, however, appear blue, protoxide of cobalt is present, wliich conceals the iron color. In this case the glass must be again .softened in the E. F., mostly removed from the coal without any adhering metal, and fused on platinum wire in a pure 0. F. In case it should then become so dark as to be nearly opaque, the soft glass is pinched out, some of it broken off upon the anvil, and the remainder diluted with more borax. It is then again treated in the O. F. until all the iron is changed to sesquioxide, when it will color the borax yellow to brownish-red, according to the amount present. Should there be, besides the cobalt, only a trace of iron, the hot glass will be green, but when cold pure blue. 184 plattxee's blowpipk analysis. A larger amount of iron colors the hot glass dark green and tlie cold glass fine green, since the sesquioxide, if not in excess, imparts a yellow color to the cold borax glass, and this with the blue of the cobalt produces green. The metals remaining after the treatment of the compound with borax in the E. F. may sometimes consist almost entirely of copper and nickel, since the volatile metals are mostly driven off and coat the coal with oxides, and they may be easily recognized by further treatment with borax or S. Ph., as will be directed under the exam- inations for the respective metals. If quite infusible compounds are to be treated, in which, besides iron and some of the above nietalsj nickel is also present, the safest way is to dissolve a little of the Bubstance in nitric acid and continue the process as will be described under native iron. Metallic ^niphidea Compounds of metallic sulphides and arsenides may '"* arBenides. be examined for iron in two ways. In the first the assay is roasted on coal, p. 78, and then small portions of it are gradually dissolved in borax on platinum wire in the 0. F. and the color of the glass examined, both when hot and cold. With many such compounds, containing only metals which do not color very intensely when oxidized, the iron is immediately obtained; with many others, however, as when they contain copper, for instance, a green color is obtained, which becomes lighter on cooling, and results from the yellow of the sesquioxide of iron and the blue of the oxide of copper. In this case the glass must be shaken off, p. 79, and treated on coal in the K. F., until all the copper is reduced out and the bottle-green color of the proto-sesquioxide of iron is obtained.* After.pinching out this glass, a bit of it may again be treated with the 0. F. on platinum wire and the iron recognized by the yellow color. The second method consists in pulverizing the substance, mixing it with test-lead and borax and fusing it on coal in the E. F., until the glass is colored by the easily oxidizable, non-volatile mctuls present. At first the whole is covered with the R. F., but as soon as the borax has united to one globule, the flame is directed upon this alone, allowing the air free access to the fusing metal. After com- pleting the fusion the glass is quickly raised with the forceps from the fluid lead and, after being treated alone on coal in the E. F. t(i reduce any trifling oxide of lead in it, is tested on platinum wire in the 0. F. Should it appear too dark it is diluted with borax until it is transparent. After sepai-atiiig the lead by means of boracic • The separation of the reduced copper is made easier by adding a very small piece of metallic lead. EXAMINATION^ FOR IKON. 18S acid, vide copper, the other metals combined with it cau easily be fect)gnized by the glass fluxes. Compounds which fuse easily alone on coal can be treated in the R. P. with borax, omitting the test-lead. Thus, for example, a very- trifling amount of iron can be found in many galenas, especially if the glass is further treated with tin. Should the glass not show a Titriol-green color, but be blue, it is treated as described above under Compounds of ^HoyS- oxides, etc. jjj compounds of oxides of iron with other metallic oxides, or with earths and acids, the iron is likewise best found by fusing the substance with borax or S. Ph. To determine whether the iron is present as sesquioxide or protoxide, the assay is added to a borax bead containing oxide of copper. In case of sesquioxide the bead becomes bluish-green ; with protoxide, red spots of suboxide of copper become distinctly visible in it. (Chapman ; Erdmann'a Journal fur pract. Chem, vol. xlvi. p. 119.) Compounds of metallic oxides not suspected of containing oxidea .of copper, nickel, chromium, or uranium, are dissolved in borax on platinum wire with the 0. F., and the colored bead held against the daylight and watched until it has so far cooled that its color remains unchanged. The bead requires no further treatment if it shows only iron, or the color of iron and cobalt together, as described before ; should it, however, show some other color, as possibly violet with much red, it must be treated some time in the E. F., which causes the violet color, resulting from manganese, to disappear, and leaves the bottle-green iron color. When much manganese is present the bead from the 0. P. appears quite dark-red while hot, and red, inclining to violet on cooling, in which case all the manganese can- not be reduced to protoxide on the wire, but the glass must be shaken ofi" and treated on coal with tin ; the manganese color then disap- pears and the vitriol-green of protoxide of iron becomes evident,, provided no protoxide of cobalt is present. In case the manganese predominatee a little iron may also easily be found by means of S. Ph., which is not colored very intensely by manganese, and readily becomes colorless in the E. P., while the color of the dissolved oxide of iron remains after treating the glass in the E. P. ; the glass usually appears reddish on cooling. When a substance contains protoxide of cobalt, in addition to th& oxides of iron and manganese, the glass obtained with borax on platinum wire in the 0. P. is colored more or less dark violet, and after a short treatment in the K. F. becomes green, and on cooling blue. In a compound containing much oxide of manganese and cobalt 18G platxxek's blowpipe analysis, with little oxide of iron, the latter may be readily found by dissolving the substance in hydrochloric acid and precipitating the sesquioxide of iron by means of ammonia from the diluted solution, or if the substance is not perfectly soluble, it is fused with bisulphate of potassa, the mass dissolved in water, a few drops of hydrochloric acid added and then a slight excess of ammonia. The precipitated oxide of iron, although not quite free from manganese, is filtered out and tested with borax or S. Ph. on platinum wire. When in addition to oxide of iron the oxides of copper and nickel are present, it is better to dissolve the substance on coal in borax with the 0. F. and then treat it with the E. F.; copper and nickel are separated as metals and the iron color alone remains. It is well to add a bit of lead, which furthers the separation of the metals; the glass can afterwards be pinched out and treated on platinum wire in the 0. F., to obtain the pure cojor of sesquioxide of iron. Should the presence of cobalt render the glass blue, it must, in fact, be oxidized on the wire, as above directed. To discover tho copper the substance is dissolved in S. Ph. and the glass treated with tin on coal, when it becomes opaque and red. When oxide of chromium is present with oxide of iron the color of the hot borax glass shows iron, but on cooling only chromium. Since, however, borax glass saturated with sesquioxide of chromium after treatment in the 0. F. likewise has, while still hot, a dark-red color, the presence of iron cannot with certainty be assumed. In such cases the substance is mixed with three parts of nitre and one of soda, and fused by degrees on platinum wire, the resulting chromate of the alkali dissolved in water, and the residue, after being washed with water, dissolved in borax on platinum wire. The iron color ia then obtained, if all the sesquioxide of chromium has been sep- a,rated and no other coloring metallic oxides are present. The iron may also be reduced with soda on coal and obtained as metal after washing away the portions not reduced. When uranium is present with iron, the borax, indeed, shows the iron color ; this, however, is not produced by the iron alone, Ijut also by the similarly coloring uranium. To obtain the pure iron color the fiubstance, if not completely soluble in acids, must be fused with bisulphate of potassa, the mass dissolved in water, and then an excess of carbonate of ammonia in solution added. The sesquioxide of nranmm, which is at first thrown down with the sesquioxide of ii'on, dissolves again, so that the iron may be separated by filtration and tested with borax, after being washed. By boiling the ammoniac.il filtrate the sesquioxide of uranium is thrown down as a yellow EXAMINATION' FOK IRON. 187 powder, and may likewise easily be recognized by testing it B. B. with S. Ph. An easier method of precipitating the uranium consists in slightly acidifying the solution with hydrochloric acid and then adding potassa. Finally, when oxides of tungsten or titanium are present with the iron, only yellow iron beads are obtained with borax and S. Ph. in the 0. P., because when combined with a maximum of oxygen the other metals (tungstic and titanic acids) only produce a feeble yellow ; in the K. P., on the other hand, the S. Ph. glass assumes a blood-red color, especially on cooling. h. Bloiupipe characteristics of the minerals containing iron enumerated above. Native iron and meteoric iron are infusible before the blowpipe. The glasses obtained with borax or S. Ph. on coal in the R. P. show only iron, and the bottle-green glass re-fused on platinum wire also shows iron alone. After dissolving the iron in nitric acid, dilutiiig and then precipitating the sesquioxide of iron with excess of am- monia, nickel, cobalt, manganese, and copper can be thrown down by Bulphide of ammonium from the ammoniacal solution, which contains the greater part of these metals present, and after settling they can be filtered out and recognized by means of borax; vide general examination for metallic sulphides, under cobalt. COMPOUNDS OF IKON WITH ARSENIC AND SULPHUR. Leucopyrite {arsenical iron, pt.) yields in the closed tube metallic arsenic. Carefully heated in the open tube much arsenous acid ia sublimed, and with moistened litmus-paper sulphurous acid can be detected. On coal copious arsenical fumes are eyolved and in the E. P. a magnetic globule remains. Roasted and treated with the fluxes it reacts only for iron. By treating the mineral on coal with borax, after being first fused alone, as will be directed under nickel for substances containing arsenides, some nickel and cobalt are found. Copper is best found by the flame test after moistening the roasted mineral with hydrochloric acid. Mispickel {arsenopyrite, arsenical pyrites) yields at first in the closed tube a red sublimate of sulphide of arsenic, but later a black, crystalline sublimate of arsenic, having a metallic lustre; in the open tube gives off arsenous and sulphurour acids. Too strong a 188 plattxee's blowpipe analysis. beat is apt to produce sublimates of suboxide of arsenic and metallic arsenic, p. 63. On coal, at first yields copious arsciiic fumes and a coat of arsenoug acid, then fuses, especially in the R. F., to a globule, which reacta like pyrrhotite, g. v. In the roasted mineral any cobalt present is readily detected with borax, p. 183. Danaiie behareslike arsenopyrite, but reacts strongly for Co when roasted. COMPOUKDS OF lEOK WITH SXILPHUE. Pyrrhotite strongly heated in the closed tube yields a little sulphur ; in the open tube only sulphurous acid. Fuses in E. F. on coal to a button, covered with an uneven black mass on cooling, magnetic and showing a yellowish, crystalline, metallic fracture. It is converted into red oxide by roasting and reacts with fluxes for iron only. Should it contain but little nickel this is best found by treating the roasted assay with gold and borax in R. F. on coal, vide nickel. Pyrite in the closed tube generally evolves an odor of sulphuretted hydrogen and gives a sulphur sublimate. If it contains arsenic a sublimate of sulphide of arsenic forms later, which appears darker or lighter, according to the amount of arsenic. The weU-ignited residue is metallic and porous, and reacts like pyrrhotite. On coal the sulphur burns with a blue flame and the residue reacts like pyrrhotite. Mftrcasite behaves like pyrite, but yields sulphur at a lower heat, and moisture is frequently perceptible. Lonehidite from the Churprinz mine, Freiberg, yields at first a sublimate of sulphur, in the closed tube, then a little sulphide of arsenic, which is reddish-yellow on cooling ; in the open tube sul- phurous and arsenous acids, at a high temperature sulphide of arsenic. On coal in the E. F. sulphur and arsenic volatilize and an arsenic coat is formed; the assay then fuses quietly to a magnetic globule and ft foeble lead coat is produced The roasted mineral dissolved in borax shows iron, cobalt, and copper with the fluxes. By a reduction assay with a gold button, which is afterwards treated with S. Ph., a little copper and cobalt can also be found. JTyrusite from the Bricciusstolln, near Annaberg, reacts like lon- ehidite in the closed tube and the open tube. On coal the sulphur bums and the mineral fuse.- to a magnetic globule without producing a notici^able coiit of arsenous acid. The EXAMINATION FOR IRON". 189 roasted powder is reddisli-brown and treated with borax shows iron and copper, p. 188. The same metals are detected by means of S. Ph. By a reduction assay with soda on coal metallic iron with an admixture of copper particles is produced. OXIDES OF IRON AND HTDRATED SESQUIOXIDES. The oxides, viz. : magnetite, ochreous magnetite, specular iron and hematite, behave in general like sesquioxide of iron, p. 103. Trifling admixtures of other metallic oxides, viz., of chromium, manganese, copper, etc., may be either found at the same time by treating the respective oxides with glass fluxes, or by special assays, as directed in the corresponding passages. The hydrates of sesquioxide of iron, viz., turgite, limonite, gSthite, xanihosiderite, etc., with clay-ironstone, bog ore, and ochre, yield water in the matrass and change to sesquioxide, the red color of which depends on the purity of the assay-piece. They fuse more or less easily on the edges in the forceps, particularly in the blue flame, while such as contain phosphoric acid tinge the outer flame bluish- green, this being observed with most certainty after moistening them with sulphuric acid. With borax and S. Ph. they all react for iron and sometimes for copper and cobalt. Clay-ironstone leaves a silica skeleton with S. Ph. A manganese reaction is obtained from nearly all of them, when fused with soda and nitre on platinum foil. SESQUIOXIDE OF IRON COMBINED WITH OTHER OXIDES. Magnesioferrite behaves like hematite (Dana). Hercynite is infusible; the ignited powder becomes brick-red and yields iron reactions with the glass fluxes. Jacoisite is infusible and with S. Ph. in K. F. gives a greenish- yellow, in 0. F. with addition of nitre, a violet- brown glass. Chromite. — B. B. in 0. F. is infusible, in E. F. can sometimes be rounded on the edges, and is then magnetic. Dissolves slowly in borax and S. Ph. to a clear glass, showing iron while hot, with borax becoming yellowish-green on cooling, and emerald-green in E. F. With S. Ph. only the chromium color in 0. F. and E. F. It is not attacked by soda, nor can a manganese reaction be obtained on platinum; but if some nitre is added the fused mass appears yellow from the formation of chromates of the alkalies. By a re- duction assay metallic iron is obtained. OXIDES OF IRON COMBINED WITH ACIDS. The sulphates of iron, viz., vielanterite or green vitriol, lotryogetit glockerite, apatelite, copiapite, jarosite, coquimbite, etc., yield more or 190 plattnee's blowpipe analysis. less water iu the matrass, which with a strong heat takes up some of the acid escaping from the assay and then has an acid reaction oc litmus-paper. The salts containing protoxide of iron at first yield only sulphurous acid. On coal in O.F. they yield their acid and are converted into sesquioxide. The other characteristic ingredients, as copper in pisanite, zinc in roemerite, and the alkalies in gelbeiseneri and jarosite, may he found by the tests described under the respec- tive substances. With soda they all give the sulphur reaction. Halotrichite fuses in the matrass in its water of crystallization, swells up and yields much water. The residue heated to redness yields sulphurous acid and turns brown. With the fluxes it shows iron, and with soda a sulphur reaction. If it is dissolved in water and the protoxide converted into sesqui- oxide of iron by boiling with a little nitric acid, a precipitate of alumina and sesquioxide of iron is obtained by adding ammonia, and these may then be separated by means of potassa, vide alumina, p. 145. Pissophanite in the matrass yields water, which has, according to Erdmann, an acid reaction. The diy mass heated to redness yields acid vapors and becomes brownish-yellow on cooling. With the fluxes, shows iron ; with soda on coal, gives an infusible, hepatic mass. Cobalt solution only produces a distinct blue when the amount of iron is not too important. If the alumina cannot thus be found ii may be detected by dissolving the powdered mineral in hydrochloric acid and proceeding according to p. 9.3. The phosphates of iron dufrenite, vivianite, and delvauxite, yield in the matrass water, which has not an acid reaction. In the forceps they swell and fuse in the blue flame to a steel-gray, metallic globule, producing a bluish-green, phosphoric acid flame. With the fluxes they show iron, and by a reduction assay with soda, or neutral oxalate of potassa, on coal magnetic iron buttons are obtained. Pseudotriplite behaves similarly, but shows a manganese reaction with soda. In alluaudite the soda conceals the phosphoric acid flame, so that the latter must be shown in some other way, vide phosphoric acid. As regards calcioferrite, it is only known that it yields water and fuses very easily to a black, lustrous, magnetic globule. Diadochite yields much water in the matrass, increases in volume,, and changes from brownish-red to yellow, losing its lustre and becoming opaque. Heated to redness it evolves sulphurous acid. In. the forceps it ex^^^ands very much and crumbles almost to powder EXAMINATION' FOR IRON. 191 A. fragment ignited in the matrass fuses in the forceps with intu- mescence to a globule and colors the flame bluish-green (phosphoric acid). On coal it intumesces very strongly and then fuses to a globule, which glows while cooling. The cold globule is steel-gray and magnetic. With soda, nearly all goes into the coal ; the fused mass yields a strong sulphur reaction, and by washing, magnetic, metallic particles are obtained. With the fluxes, shows iron. Cacoxenite yields water, the latter portions of which have an acid reaction on Brazil-wood paper; the liberated hydrofluoric acid attacks the glass, and rings of silica are seen after driving the water from the matrass. B. B., it fuses on the edges to a black, metallic slag, and gives a distinct phosphoric acid flame. Dissolves easily in borax and S. Ph., showing iron. With soda it at first fuses with effervescence, but afterwards the phosphate of soda sinks into the coal, leaving a black, infusible mass. It dissolves in hydrochloric acid and leaves only a very slight amount of silica. If the mineral is treated as directed for' lazulite, p. 135, the oxide of iron, alumina, lime, and silica can be found. Childrenite yields much water. B. B., swells and ramifies, giving a distinctly bluish-green flame and forming a fissured, partly black and partly brownish-red mass, rounded on the edges. With the fluxes, shows iron and manganese (Eammelsberg). Beudantite. — The variety from Dernbach decrepitates a little when heated, yields water and turns bronze-color. B. B. fuses on the edges; with sulphuric acid a bluish-green flame coloration. On coal swells; fuses, gives a lead coat, leaving a black, magnetic slag, which has a hepatic reaction on silver. The variety from Ireland is infusible; with the fluxes reacts for iron and copper. That from Horhausen yields on coal an arsenic odor. The carbonate of iron, siderite, spathic iron, sometimes decrepitates in the matrass, gives ofi' carbonic acid and oxide, blackens and is con- verted into magnetic oxide. With the fluxes, hke sesquioxide of iron. Soda sometimes produces a manganese reaction. Any lime or mag- nesia that may replace some of the iron can only be found in the wet way, vide carbonates, under magnesia, p. 136. Humboldtine yields water and blackens in the matrass. On coal it blackens, but in 0. F. soon becomes red. With the fluxes, shows iron. Ludxvigite in the matrass in part becomes brown. In the forceps thin splinters fuse at the tip to a black, slaggy, magnetic mass, while the rest of the piece becomes reddish-brown; no flame color- ation. Powdered, with sulphuric acid on wire gives a green flame. 192 plattner's blowpipe akalysis. Glass fluxes show iron ; the magnesia can only be detected in the wet way. The arsenides of iron, including arf:eniosiderite,2}harmacoBiderite, and scorodite, yield neutral water in the matrass. B. B., in the blue flame fuse to a gray slag, with a metallic lustre, and color the outer flame light blue. On coal, giye off arsenical fumes and fuse in R. F. to a gray, metallic, magnetic slag, which gives the iron reactions with the fluxes. Pitticite yields water and at a high temperature sulphurous acid. In the forceps and on coal, like scorodite. With soda, yields arsenical fumes and sinks mostly into the coal, giving a strong sulphur reaction on silver. Carminite fuses on coal with evolution of arsenical fumes to a gi-ay slag, and at the same time a lead coat is formed, or may certainly be obtained with the addition of soda. With the fluxes the iron reactions are produced. Symplesite from Lobenstein heated to 100° 0. is unchanged; abova this heat it yields water (246 per cent.) and becomes brown ; at a red heat a notable amount of arsenous acid is evolved, and a moist- ened slip of litmus-paper introduced into the neck of the matrass ia feebly reddened. B. B., it is infusible in 0. P. ; touched with the tip of the blue flame it fuses on the edges and colors the outer flame light blue. On coal in R. F. gives a strong arsenic odor and blackens, but fuses only on the edges and then is magnetic. After ignition in the matrass or on coal a fragment dissolves in the glass fluxes, showing iron, but in borax a good 0. P. affords a somewhat brownish-yellow glass. If enough is dissolved on coal to make the borax glass quite opaque, subsequent reduction will produce fusible globules of a metallic arsenide, which may be collected by means of a gold button and tested in 0. F. for nickel with S. Ph., vide nickel. With soda on coal, gives a strong arsenical odor and the absorbed mass reacts feebly for sulphur. With soda and nitre, a slight man- ganese reaction. Beiidantite yields water. B. B., alone, the Cork crystals are infusible, but yield on charcoal fumes of sulphurous acid and afford a yellow slag, and with soda a kei'nel of lead ; the Dernbach fuse easily on charcoal with intumescence to a globule of lead, mixed •with a black hepatic slag; the Horhausen fuse easily, affording a gray slaggy globule, and after long blowing the odor of arsenic (Dana). Durangite, p. 139, blackens transiently in the matrass; strongly heated gives a feeble, white, etching sublimate, and melts to a yellow glass. In the forceps fuses very easily, with intense soda flame. On coal a white coat and strong arsenic odor. With the glass fluxes shows iron and manganese. EXAMINATION FOR IKOH. 193 COMPOUIfDS OF PROTOXIDES OF IRON AND MANGANESE WITH TUlfGSTIC ACID. Wolframite sometimes decrepitates in the matrass and often yields traces of water. In forceps and on coal, fuses without diflBculty to a, globule, the surface of which consists of accumulated lamellar, iron-gray crystals, haying a metallic lustre. It is thus distinguished from titanic iron, which is infusible in the 0. P. Dissolves rather easily in borax in 0. F. to a clear glass, in which the iron or manganese reaction predominates, according to the com- position of the specimen, so that with a certain addition the varieties poor in iron can be distinguished from the richer ones ; in the former the glass is rather reddish-yellow on cooling. In E. P. only the iron reaction. With S. Ph. in 0. P. shows only iron and manganese, but in R, P becomes dark red and opaque, even with a moderate addition of the mineral. By treating the not too highly saturated glass on coal with tin in the E. P. for a very short time, it becomes green on cooling, but by then employing a good E. P. the green color disap- pears, leaving a pale reddish-yellow, which remains unchanged With soda and nitre it gives a strong manganese reaction. Por the detection of the tungstic acid, vide tungsten. COMPOUND OF PROTOXIDE OF IRON, ETC., WITH TITANIC ACID. Menaccanite {titatiic iron). Infusible in 0. P., but can be some- what rounded on the edges in E. P.' With borax and S. Ph, in 0. P like sesquioxide of iron, but the S. Ph. bead treated a while in R. P. assumes on cooling a more or less intense brownish-red color ; by the depth of the red the relative amount of titanium can be estimated. On coal with tin this glass becomes violet-red, unless too little titanium is present. By fusion with bisulphate of potassa the mineral is decomposed, vide titanium. With soda and nitre it frequently gives a feeble manganese reaction. COMPOUNDS OF PROTOXIDE OF IRON, ETC., WITH TANTALIO ACID. Tantalite from Tammela, as well as Pin bo, free from tungstic acid, behaves as follows: — B. B. on coal and in the forceps it is infusible. Dissolves slowly in borax to a glass colored by iron, which at a certain saturation becomes grayish-white by flaming, •especially after previous treatment in E. P., owing to the tantalic 194 plattnek's blowpipe analtsis. acid. When fully saturated it becomes cloudy of itself on cooling In S. Ph. dissolves also slowly to a bead colored with iron, which treated in R. F. becomes pale yellow on cooling, but not red, showing that no tungstic acid is present. "With coal on tin the glass becomes green. "With soda and nitre manganese is detected, and by a reduction assay with soda and a little borax, the latter serving to dissolve the tantalic acid compound and prevent the reduction of the iron, some tin can be obtained. If further evidence of the tantalic acid ig desired it may be obtained by proceeding as directed under tan- talum. Tantalite from Broddbo, containing tungstic acid, behaves like the above, except that the S. Ph. bead treated in R. P. becomes dark-red on cooling, and retains this color when treated with tin on coaL Also gives a strong manganese reaction. Tantalite from Kimito, having a cinnamon-brown powder, behaves, according to Berzelius, like a tantalite free from tungstic. acid and containing manganese and some tin. Tapiolite. — B. B. like tantalite, but no manganese reaction (Dana). COMPOUlfD OF PROTOXIDE OF IROX, ETC., WITH NIOBIC ACID. Columhite is infusible. Dissolves easily in borax to a bead, colored by iron, which can only be made opaque by flaming after strong saturation, and especially when first treated in R. F. With S. Ph. like tantalite free from tungstic acid. With soda and nitre it shows manganese, and by reduction on coal with borax and soda traces of tin are obtained, which with S. Ph. on coal frequently react for copper. The manner of detecting niobic acid will be given under niobium. SILICATES. Most of the silicates enumerated on p. 181 et seq., yield more or less water in the matrass. Pyrosmalite at a high temperature also gives off yellow sesquichloride of iron, which dissolves in the latter portions of water, and causes an acid reaction on litmus-paper ; a suffocating odor is also perceptible at the mouth of the matrass. Their relative fusibility is indicated by the aflBxed numbers. Generally, if the blue flame has been used, the fased assay is mag- netic. Some of them dissolve easily in borax, others with diflOiculty, and antJwsiderite only very imperfectly, even in powder. The glass usually shows only iron; with S. Ph. they behave similarly, but those which have perfectly soluble bases leave a skeleton of silica. . EXAMINATION FOK IRON. 195 "With a little soda they fuse mostly to a bead, but with more tl ose that have a low ratio of silica fuse to a slag-like mass. Several yield a manganese reaction with soda and nitre. To detect the earthy constituents in certain of these silicates, the method described under lime, p. 128, is to be followed. e. Examination for iron in metallurgical products, with the iloivpipe characteristics of the latter. Raw iron and steel are usually only examined for accessory in- gredients, viz., manganese, p. 174, carbon, silica, sulphur, and phos- phorus {vide the respective examinations). The method of testing tears, llach copper, and impure lead and tin, for iron and other accessory ingredients, is evident from what was said about metallic compounds containing iron, p. 183. The various speisses are very easily examined. They behave as follows: — In the open tube most of them yield sulphurous and arsenous acids, although certain of them must be first pulverized. On coal in E. P. they fuse to a globule and yield up their excess of arsenic, if the latter exceeds the propor- tion (Ni, Co, Fe)' As. Volatile metallic sulphides present, as Pb S, Sb" S', form a coat of oxides of lead and antimony, these being mixed with sulphate of lead. Should there be so much iron that the coat forms with difficulty, the iron must first be mostly removed by treatment with borax on coal, and the remaining button will then yield a distinct coat when treated alone. If the speiss contains bis- muth, as is the case with cobalt speiss, a bismuth coat is obtained {vide p. 66, et seq). When the fused button of speiss is treated with borax on coal, iron oxidizes first, then cobalt and the resulting oxides dissolve at once, while arsenic volatilizes and is perceived by the odor. As soon as the button shows a bright surface the blast is stopped, the button quickly lifted out, and a portion of the soft glass withdrawn with the forceps, and if quite opaque, treated on platinum wire in the 0. P. with borax. It will show either iron alone, or cobalt likewise, p. 183. The button is to be treated on coal with fresh borax, when, if all tlie iron and cobalt were removed before, the glass will show only nickel, but if some cobalt still remained the glass Avill be colored by it also, and if there is much cobalt will be, indeed, pure smalt-blue. In this case still a third, or even a fourth treatment with borax may be necessary, and then only the nickel color will be observed. Should the speiss contain copper, this metal would not be detected 196 plattner's blowpipe analysis. by means of borax, being less easily oxidized than nickel, but may be very readily found if the button, freed from iron and cobalt and now containing only ISI^i' As and more or less Cu'' S, is treated on coal in the 0. F. with S. Ph. Copper and nickel are then oxidized, and the glass bead is yellowish-green, retaining this color on cooling, owing to the yellow of the nickel and the blue of the copper. Treated with tin on coal, this bead becomes red and opa([ue from suboxide of copper, when cold. It is assumed that all the antimony has been previously removed by treating the speiss alone on coal, so that the bead shall not become black on cooling. When there is so much sulphide of lead in the speiss that the coat of oxide of antimony cannot well be distinguished from the simul- taneously formed sulphate of lead, it is only necessary to treat the powdered speiss with soda in the K. F. The sulphur is separated by the soda and the lead then forms only a yellow coat, allowing the oxide of antimony to form a pure coat. When there is a considerable amount of sulphide of zinc a slight zinc coat is also formed, but if the amount of zinc is trifling it cannot always be shown with jertainty. In treating a very impure speiss, containing many sulphides, a little of it may, after the presence of volatile metal has been ascer- tained by treatment on coal, be well roasted and then treated with the fluxes as described on p. 184. The various matt-like products, p. 182, evolve in the suipwdls. open tube sulphurous acid and, if they contain sulphide of antimony, deposit near the assay a thin, fixed sublimate of oxide of antimony and antimonic acid. On coal in K. F. they fuse to a globule, with the exception of Rohofenbrucli rich in zinc, and coat the_ coal with oxides of lead, antimony, and zinc, and sulphate of lead, when they contain volatile sulphides of these metals, and have not very little sulphide of zinc. Occasionally also the odor of arsenic is perceptible; otherwise a special test may be made for it, vide arsenic. To detect the other ingredients, a suflBcient amount is roasted on coal and tested first "with borax and S. Ph., as directed for the com- pounds of oxides of iron with other metallic oxides, p. 184 et seq. Another roasted portion is treated in the R. F. with soda, so as to produce metallic iron and copper, and to recognize any small amount of zinc by the coat which is formed in the immediate neighborhood of the assay. Slags vary so much that it is not possible to establish any general blowpipe characteristics for them, but it is very easy to find, by means of their behavior alone on coal and with the glass flaxes, what metallic bases they contain, and :'egard must be had to these when COBALT. 197 effecting their decomposition, partly in the dry way and partly in the wet way, according to p. 138. 4. Cobalt, Co. Its occtirrence in the mineral kingdom- and in metalhirgical products. Cobalt occurs under different conditions' in the following minerals : a. Combined with arsenic in Smaltite {cMoanthite, part). The minerals included under this name contain arsenides of cobalt, iron, and nickel, in various combinations. R AsS x^R As= + R S', xR' As' + R S', xR As + R S', etc. X is always a large figure; R = Co (Ni, Fe). The Co varies from a few to 23 per cent. Spathiopyrite {safflorite) contains Co, Fe, (Cu), As, (S), with 14.9 Co ; Skutterudite,— Co As', with 20.8 Co. There is also a little Co in Nicoolite, | . , . , , T. > 1. -J. tf'Me nickel. Bammelsbergite, \ i. With arsenic and sulphur in Cobaltite, — Co S'' + Co As", with 35. 5 Co, of which, however, a few per cent, are replaced by Fe; Glaucodot,— (Co, Fe) S'' + (Co, Fe) As"; Danaite, KobaUarsenkies, vide iron. Gersdorfflte, vide nickel, also contains a little Co. c. With sulphur in Syepoorite,— Co S, with 64.4 Co ; Linnaeite {cobalt pyrites) from Siegen, — 2 R S, 3 R" S' ; R = • Co, Ni, Fe; with 14.6 to 43.6 Ni and 11 to 40.7 Co; CarrolUte,— Co' S' + Cu S. d. With seleniiim in Tilkerodite {cobaltic clausthalite, Dana), — Co Se' + 6 Pb Se, with 64.2 Pb and 3 Co. e. As oxide, with other oxides in Asbolite {earthy cobalt), vide manganese. /. Combined with acids : a. With sulphuric acid in Bieberite, — Co S 0* + 7 H" 0; with 20 Co when pure, but usually with mixture of Ca 0, Mg 0, and Cu 0. The variety from Bieber, near Hanau, contains almost 4 per cent. Mg 0. /?. With carbonic acid in Sphaerocobaltite, — Co C 0", with 50.4 Co, but containing trifling admixture of Ca 0. 198 plattnek's blowpipe analysis. y. With arsenic acid in Erythrite,— Co= As'' 0= + 8 H" 0, with 29.5 Co, of which a small part is sometimes replaced by Ni and Fe; Earthy cobalt bloom {Kobaltheschlag), probably a mixture of erythrite and arsenous acid; Lavendulau contains Co 0, Ni 0, Cu 0, As' 0', H' 0; Kottigite, vide zinc; roselite, vide lime. Annabergite, vide nickel, also contains a little Co 0, Among cobaltiferous metallurgical products the speisses need mention; for their composition vide iron. Raffinatspeise (refined speiss) approaches the formula (Ni, Co)'' As. In matts also, vide iron, cobalt is often found, and in slags from smelting cobaltiferous ores and products, as well as in refining black copper containing cobalt and nickel. Examination for Cobalt. Including the blowpipe characteristics of the above minerals and products. a. General examination for cobalt. Cobalt is very easily detected, since it oxidizes quite readily and then imparts a smalt-blue color to the borax and S. Ph. beads, which remains the same in both 0. E. and E. F. Cobalt must be oxidized for the bead colorations. The metal oxidizes rather easily. It is reduced from the beads only by a long and strongly reducing blast, very gradually separating as metal, nfckei*^ Metallic nickel, which is infusible, is converted into arsenide before testing it for cobalt, by mixing it in thin scales, or filings, with a little metallic arsenic, fusing them together in a cavity on coal with the R. F. and treating the fused button .a short time with borax directly with the tip of the blue flame; if any cobalt is present the glass becomes blue, and if the amount is not too trifling the cleansed button will impart a blue color to a fresh portion of borax also. ^°^meMa'°^ The manner of finding cobalt in alloys has been described under iron, p. 183. Compounds of cobalt with arsenic and other metallic arsenides are fused on coal until they cease to evolve arsenic, and then borax •reeSdes. ^^ added and fused with the metallic compound, now con- taining less arsenic, until the glass is colored. It will be pure smalt-blue, unless iron is present, which oxidizes sooner than cobalt, and produces, at the same time, the color of its proto-see- EXAMINATION FOE COBALT. 199 quioxide. The cleansed tutton treated with fresh borax will, however, show the pure cobalt blue. Any nickel and copper present will be combined with arsenic or sulphur, and do not oxidize until all the cobalt has been separated by repeated fusions with borax in 0. F. When the fresh borax no longer assumes a blue color, but is brown from nickel, the remaining button is treated with S. Ph. in 0. F. and the glass becomes green, both when hot and cold, if copper as well as nickel is present. On coal with tin it becomes opaque and red from suboxide of copper. Any bismuth is immediately recognized by the coat formed while removing the excess of arsenic by treating the substance alone on coal. If no antimony is present the coat may be tested with S. Ph. and tin, vide bismuth. Metallic arsenides in which cobalt forms a chief constituent may be roasted and tested with the fluxes aa directed for sulphides, but the above method is always the shortest. Sulphides, sometimes containing arsenides, are first treated alone on coal in R. F. until they cease to yield anything volatile. The coats then formed will indicate any admixture of lead gJip^Jje^ or bismuth. The fused compound is powdered, well roasted, and a part of it at once tested on coal with borax in 0. F. If no coloring oxides except cobalt are present the glass will be blue and remain so when diluted with borax and tested on platinum wire in 0. F. A trifling amount of iron will, however, then render the glass green while hot. If copper or nickel are present their oxides will likewise dissolve and sometimes entirely conceal the cobalt color. By treating such a glass on coal, however, in the E. F., until it appears transparent while fused and few or no bubbles escape from it, the copper and nickel are reduced to metal, and either the pure cobalt will appear, or the cobalt color mingled with the bottle-green of iron. The separation of the metals is promoted by adding a little test-lea'd, p. 81, but then the metallic compound obtained should be freed from the excesS of lead by treating it alone on coal, after which it is fused in 0. F. with S. Ph. to detect nickel and copper, which will give a green bead. Gold may be used in place of the lead, vide nickel. Metallic selenides are first treated alone and then with ^^1^™^ borax on coal in E. F., until the glass is colored by the easily oxidized, fixed metals. Should the glass not show a pure cobalt color, it is treated as above described. , In treating metallic oxides or their salts, in which protoxide of cobalt forms a chief, or accessory ingredient, a small quantity is fused with borax on coal in E. F., until all the °*stitef°^ non-reducible oxides are dissolved, while the others are 200 plattij^er's blowpipe analysis. reduced to metal, and such as are volatile have been volatilized. If oxides of cobalt, iron, and manganese are. present, the iron dissolves as proto-sesquioxide, and the manganese as colorless protoxide, so that the glass has a mixed blue and bottle-green color, very easily distinguished from the green produced by iron alone in E. F., even if little cobalt is present. This glass in 0. F. on platinum wire only shows cobalt and iron distinctly when manganese is absent ; otherwise the manganese becomes more highly oxidized and, coloring the glasa intensely, conceals the cobalt. The metals separated by treating the glass in E. P. may form a button, e. g., when much arsenate of nickel is present, and they can be further tested with borax and S. Ph. b. Blowpipe characteristics of the minerals containing cobalt above indicated. COMPOUNDS OF COBALT WITH ARSENIC. Smaltite usually yields in the closed tube metallic arsenic. Care- fully heated in the open tube an abundant crystalline sublimate of arsenous acid is obtained, and sometimes sulphurous acid. In powder it is converted into basic arsenate of cobalt. It fuses on coal, with evolution of arsenic fumes to a grayish-black, magnetic, metallic button, which is brittle, and with borax, p. 198, behaves like arsenide of cobalt containing a little iron and nickel. Skutterudite gives a strong sublimate of arsenic in the closed tube, otherwise like smaltite. Safflorite behaves like smaltite; also shows copper by the S. Ph. treatment, after slagging off iron and cobalt. COMPOUNDS OF COBALT WITH AESENIC AND SULPHUK. Cohaltite (glance cobalt) yields in the closed tube only a very little arsenous acid formed by the air in the tube. In the open tube at a red-heat it yields arsenous acid and sulphurous acid. On coal it yields sulphur and arsenic and fuses to a button, which reacts with borax like arsenide of cobalt containing iron. By treating it further with borax, p. 198, adding gold to increase its volume, any nickel present may be detected- Olaucodot loses its lustre in the closed tube ; otherwise Uke cobalt- ite in the closed and open tubes. It fuses quietly on coal in the E. F., yielding sulphur and arsenic to a button, which on cooling has a black, rough surface, but a fine- grained, speiss-like fracture, and is slightly magnetic. EXAMINATION^ FOE COBALT. 301 This button, treated with borax, according to p. 199, first shows a strong iron reaction; with fresh borax only pure smalt-blue, and if finally gold is added to increase the volume of the little button remaining, and the treatment with borax continued, the last traces of the metallic arsenides oxidize and show a feeble nickel reaction. S. Ph. serves yet better than borax to detect the nickel. COMPOUNDS OF COBALT WITH SULPHUE. Syepooriie. — The blowpipe characteristics of the natural minora] are not known. The artificial yields sulphurous acid in the open tube ; nothing in the closed. On coal it fuses to a globule, which even after long treatment with the K. P, still shows a bright surface on cooling, and is magnetic. The roasted powder shows pure cobalt reactions with the fluxes. Lmnmite from Siegen yields a slight sulphur sublimate in the closed tube; and much sulphurous acid in the open tube, with a very little arsenous acid. If used in powder it becomes black on cooling. On coal, small fragments of crystal fuse in the E. P., with some evolution of sulphur, to a globule, -which can be kept fluid for some time with the surface free from oxide, and forms no coat. When cold it is covered with a black, rough oxide film, probably magnetic oxide of iron, and both the whole globule and fragments free from oxide follow the magnet. The roasted powder affords reactions for cobalt, iron, and nickel. By reducing some of the roasted powder with neutral oxalate of potassa, a magnetic, metallic powder is obtained. (Had tlie metals been combined partly or entirely with arsenic, the roasting would have formed basic arsenates, and by reduction globules of metallie arsenides would be produced.) Carrollite behaves like niccoliferous linnaeite, but the roasted mineral also reacts for copper with the fluxes. (Dana.) COMPOUND OF COBALT WITH SELENIUM. Tilkerodite yields in the closed tube a sublimate of selenium. On coal, evolves the odor of selenium, coats the coal with selenium and oxide of lead and tinges the flanle azure-blue. The assay decreases in volume, without fusing perfectly, and leaves finally an unalterable scoria, which gives iron and cobalt reactions with borax, COMPOUNDS OF PKOTOXIDB OF COBALT WITH ACIDS. Bieberite yields in the matrass water and on continued heating sulphurous acid. With the fluxes it reacts like oxide of cobalt. The 202 plattner's blowpipe analysis. magnesia can only be found by dissolving the salt in water and then separating the bases according to p. 139. Sphmrocohaltite in the matrass blackens below red heat. Little attacked by cold acid, but soluble on heating, with lively evolution of carbon dioxide. With the glass fluxes gives pure cobalt colors. Erythrite yields in the matrass only water. The red crystals from Schneeberg glow, and on cooling are dark, dirty violet. (At a higher heat, gives off arsenous acid and becomes gray or black. Dana.) B. li. in the forceps the crystals fuse and color the flame light blue On coal it evolves arsenical fumes and fuses in K. F. i» a blackish- gray globule of arsenide of cobalt, which with the fluxes reacts only for cobalt. Earthy colalt bloom yields in the matrass water and arsenous acid. On coal and with fluxes, like erythrite. Lavendulan yields only water. The assay becomes lamellar and is bluish-gray when cold. In the forceps fuses easily and colors the flame light blue. The fused assay crystallizes with large faces on cooling, hke phosphate of lead. The crystals are generally black and opaque, but some have a dark hyacinth-red color. On coal in K. F. it fuses and seems to be reduced, while a strong arsenical odor is perceptible. With the fluxes, shows cobalt, nickel, and copper, p. 199. c. Examination for cobalt in metallurgical products. The method of proceeding may be deduced from the examinatioQ for iron in general, p. 183, and in case of products, p. 195. 5. Nickel, Ni. Its occurrence in the mineral kingdom and in metallurgical products. Nickel occurs under different conditions in the following minerals : a. Combined with other metals in Breithauptite, — Ni Sb, with 32.3 Ni, but frequently rendered im- pure by a little Fe, As, and disseminated galena. Meteoric iron, vide iron. Melonite, Ni" Te', with 23.5 Ni, deducting some Ag= Te and Pb Te. 6. Combined with arsenic in Niccolite {copper nickel), — Ni As, with 43.6 Ni, but seldom free from a little Co, Fe, Sb, and S; some varieties correspond to Ni (Sb, As); NICKEL. 203 Eammelsbergite and chloanthite, — Ni As", with 28.3 Ni, having a part of the Ni frequently replaced by Co and Fe, and contain- ing occasionally some S; vide also cobalt.' Smaltite, vide cobalt. c. With antimony, arsenic, and sulphur in Ullmannite,— Ni S' + Ni Sb', with 27.6 Ni, and sometimes a 1-ttle Co and Pe; As is often present ; Gersdorffite and amoibite, approximately Ni S" + Ni As', with 30 to 35.2 Ni, sometimes partly replaced by Co and Fe; Antimon-Arsennickelglanz (corynite, wolfachite), is a variety of ullmannite with the formula Ni S" + Ni (Sb, As)", containing 25.3 to 39.8 Ni; d. Combined with sulphicr in Millerite,— Ni S, with 64.4 Ni; Beyriohite, — 3 Ni S + 2 Ni S', with 56.4 Ni, but containing some Fe ; Pentlandite,— 2 Po S + Ni S, with 21.8 Ni ; Horbaoliite,— 4 Fe'' S' + Ni' S, witli 12 Ni ; Polydymite,— E« S' ; E = Ni, Fe ; witii 43.2 Ni ; Griinauite (bismuth nickel), pertiaps a mixture of polydymite with bismuth ; Llnnseite, mde cobalt. e. In the oxidized state in Bunsenite,— Ni from Johann-Georgenstadt, accompanied by bis- muth and annabergite, and containing 78.3 Ni ; /. Combined with acids : a. With carbonic acid in Zaratite {emerald nickel),— 3 Ni C 0= + 6 H' 0, with 46.5 Ni. /?. With sulphuric acid in Morenosite {nickel vitriol),— iii S 0< + 7 H'' O, with 20.3 Ni. y. With arsenic acid in Arsenate of nickel (anhydrous), from Johann-Georgenstadt. According to Berg- mann, the yellow variety is Ni' As'' O", with 38.5 Ni ; the green variety Ni' As" 0'" with 48.6 Ni ; both contain a little Co 0, Cu 0, and Bi' 0' ; Annabergite {nickel ochre),— m- As^ 0' + 8 H" 0, with 29.2 Ni, sometimes a little Co 0, Fe 0, and S 0'. S, With silicic acid in Eottisite II-III, — perhaps Ni 0, Si 0' -f- H' ; contains also a little CoO, CuO (Fe, Al)" 0=; P' 0° and As" 0», with 39.1 Ni. Couarite is similar. 204 plattneb's blowpipe analysis. Garnierite, nickel gymnite, pimelite, genthite, numeite, alipite. These, possibly mixtures, consist of Si 0^ Fe O, Ni, 0, Mg 0, H= O, and in some of them some Zu ; Ni = 3 to 33 per cent. Small quantities of nickel are also found in Chrysolite and olivine, vide magnesia; Magnetite, vide iron ; Chrysoprase, vide quartz and silicic acid. Several metallurgical products contain nickel, when obtained from niccoliferous ores. It is usually concentrated in combination with arsenic and arsenides of cobalt and iron, either in the sulphide com- pounds, (matts, regulus) obtained from smelting certain silver, lead, and copper ores, and then forms only an admixture, vide iron, p 183; or it settles in combination with arsenic and other arsenides, as well as with metallic sulphides, as a special product, viz., speiss, lead speiss, vide cobalt, p. 198. It further forms the chief ingredient of the speiss obtained by smelting cobaltiferous nickel ores, to concen- trate the arsenides of cobalt and nickel in the ores, as well as of refined speiss and cobalt speiss, p. 198. Occasionally also it forms an accessory ingredient of black copper, obtained in the large way, and of certain slags. Ezasunation for Nickel, Including the blowpipe characteristics of the minerals above mentioned, a. General examination for nickel. Nickel can be detected with certainty and comparative ease, etan -when in yery trifling quantities. For its reactions with the fluxes, vide p. 82. It can be reduced by E. F. from borax in the form of scales or powder ; from S. Ph. reducible only in part and very .slowly. Fusible alloys containing nickel are melted for some time with borax on coal in R F. and the glass tested on platinum wire °^'' in 0. F., vide p. 183; notice being also taken of any coat formed on the coal. The remaining metallic button is again tested with borax in K. F., to ascertain whether the glass still takes up any oxides of the non-reducible metals, or whether it remains colorless. In the latter case the button is treated with S. Ph. in 0. F., to dis- cover whether only the nickel coloration results, or whether copper is likewise present, in which case a green, or yellowish-green glass is formed, which remains green on cooling, and with tin on coal iecomes opaque and red. Should antimony or bismuth, however, be JSiAMINATION FOR NICKEL. 205 jilso present, the glass bead becomes black on cooling and the copper reaction is thus concealed. It is then necessary to employ a new piece, and before using the fluxes, to treat it alone on coal in R. F., until it ceases to yield anything volatile. When the alloy is infusible and consists especially of iron, the process indicated for native iron may be followed, p. 187; but when it seems to consist chiefly of nickel and cobalt, these may be con? verted into arsenides, as described on p. 198, for testing metallic nickel for cobalt. Compounds of nickel with arsenic and arsenides, or sulphides, which sometimes contain arsenides, are treated sna^SphWes. just like the corresponding cobalt compounds, p. 198, and p. 199. In metallic oxides and their salts, the nickel, if not in too small quantity, can be found by the method given for the cor- responding cobalt compounds, p. 199, but a very trifling ^*^'d sa^fs.**' amount cannot always be thus detected with certainty. It is then safer to proceed as follows. Suppose it is desired to test a combination of oxides of cobalt, manganese, and iron for a trifling amount of oxide of nickel ; a sufficient quantity should be dissolved in borax on platinum wire in 0. P., the very dark, or quite opaque bead shaken ofi', and two or three such beads prepared. These are treated in a cavity on coal, or in a coal crucible, with a pure gold button of fifty to eighty milligr. weight, in a strong, active E. F., until it is certain that all of the nickel is reduced from the bead and •collected in the gold button, which has been brought into contact with every portion of the fluid glass by carefully turning the coal. "When the button has solidified it is lifted from the glass and freed from any adherent glass between paper on the anvil. A trifling -amount of nickel suffices to render the button more or less gray and harder under the hammer than pure gold. If the borax-glass was not supersaturated with oxides, so that none of the cobalt could be reduced, the gold button treated for some time in 0. P. on coal with S. Ph. will impart to this only the nickel color ; reddish to brownish- red while hot, and yellow to reddish-yellow after cooling, according to the amount dissolved. If, however, cobalt had been reduced, it will oxidize sooner than the nickel, and either produce a blue cobalt bead only, or a bead which will be dark-violet when hot and dirty green on cooling, if some nickel had been oxidized. In either case the button, freed from glass, is treated with fresh S. Ph. in 0. P., until the hot glass seems colored, when, if the original borax beads ihad not been too highly supersaturated, the glass will show only the 206 PLArrNERS blowpipe analysis. nickel coloration; if the metallic oxides were, however, free from nickel, the glass will be colorless. When the oxides or salts contain other coloring oxides which are likewise reduced in the metallic state from the borax beads, as oxides of copper, the gold button will contain both nickel and copper, and, after being freed from any trifling amount of cobalt by means of S. Ph., will yield with a fresh portion of that salt a glass which is green while hot, even if the copper predominates considerably, and remains green on cooling, but treated with tin becomes red and opaque. If the assay was perfectly free from nickel the hot S. Ph. bead will, indeed, be green, but it becomes blue on cooling.* i. Behavior of the above-mentioned niccoliferous minerals before the COMPOUNDS OF NICKEL WITH ANTIMONY, AESENIC, AND STJLPHUE. Melonite, vide under tellurium. Breithauptite in the open tube evolves copious antimonial fumes, without fusing ; the assay is grayish-green on cooling. It fuses on coal in E. E., and after the blast is stopped continues to emit fumea for a short time, like antimony, but without becoming covered with oxide of antimony. On renewing the blast a coat of oxide of anti- mony is formed, near which a yellow lead coat may be produced by disseminated galena. Should the mineral alone give no arsenic odor, ithis becomes perceptible on adding soda, and the soda will also afford a sulphur reaction in case the assay was not quite free from galena. The glass obtained with borax on coal in E. F. shows only iron, and also when this glass is afterward treated on platinum wire in 0. P. only an iron coloration is produced, but by treating the remaining button with fresh borax in 0. F., the nickel reaction is obtained. Niccolite, free from antimony, yields a very little arsenous acid in the closed tube, but in the open tube it yields arsenous acid abun- dantly and sometimes sulphurous acid ; the assay becomes yellowish- green and crumbles to powder. On coal it yields arsenical fumes and fuses to a button, which treated a short time with borax shows cobalt and iron, and these are very distinctly seen when the glass is remelted on platinum wire in 0. F. A feeble lead or bismuth coat • A gold button containing nickel or copper is pnrified by fnsing it with a suitable %moiint of test lead, cupelling it on bone-ash, and, if necessary, treating it with boracic tcid on coal. NICKEL WITH ANTIMONT, ARSENIC, AKD SUL1*UUR. 207' is sometimes formed and the remaining button shows nickel re- actions. The blowpipe characteristics of the antimonial niccolite from AUemont and Balen are not known, but the various constituents- might be found as in breithauptite, while the mineral probably alsa shows a behavior similar to that of uUmannite below. Bammelsierffite and chloantJnte behave like niccolite, but yield metallic arsenic in the closed tube ; the residue then corresponds to niccolite. "With the fluxes a little cobalt and iron can generally also be detected, while a trifling bismuth coat is occasionally formed. UUmannite {niccoliferous gray antimony) yields a trifling white sublimate in the closed tube, and in the open tube copious antimo- nial fumes and sulphurous acid. On coal in E. P. fuses to a globule and evolves antimonial fumes, which partly coat the coal. Some times arsenic replaces part of the antimony and may be detected by its odor, which is most perceptible when the assay is fased in 0. P. with test lead, vide arsenic. "With the fluxes, iron, cobalt, and nickel are detected as described under niccolite. Gersdorffite {nickel glance) decrepitates in the closed tube and yields a yellowish-brown sublimate of sulphide of arsenic. In the open tube avsenous and sulphurous acids. On coal yields sulphurous and arsenical fumes and fuses to a globule, which gives with the fluxes iron, cobalt, and nickel reactions, vide niccolite. Antimon-ArsennicTcelglanz gives the reactions of both uUmannite and gersdorffite. Millerite yields sulphurous acid in the open tube. On coal fuses rather easily to a globule which spirts strongly and diminishes somewhat in volume, but remains fluid, lloasted and then treated with a good E. P., it yields a coherent, somewhat malleable, metallic, and magnetic mass. Well-roasted millerite gives the nickel reactions with the fluxes, but frequently a little iron and copper can be detected. Beyrichite decrepitates in the matrass, giving a sulphur sublimate and becoming yellow and harder. On coal melts easily to a mag- netic globule. Horbachite, unaltered in the matrass, melts easily on coal to a magnetic globule. Polydymite decrepitates strongly in the matrass ; on strong heating yields a sulphur sublimate and a very trifling yellow- ish-brown one of arsenic sulphide. The residue, on coal, melts easily (yielding an extremely small antimony reaction) to a 208 plattner's blowpipe analysis. blackish -green^ magnetic button, crystalline and speiss-yellow on the fracture. Pentlandite in the open tube yields sulphurous acid, On coal fuses to a globule, having a yellowish, metallic fracture. Roasted and tested with borax, shows chiefly nickel and iron, with a little copper from disseminated chalcopyrite. PROTOXIDE OE NICKEL. For its reactions with the glass fluxes vide p. 83; with soda on coal in E. F., yields metallic nickel. PROTOXIDE OF NICKEL COMBINED WITH ACIDS. Zaratite at 100'^ C. yields much water in the matrass and assumes a black color. It dissolves with efEervescence in the fluxes and behaves like protoxide of nickel. Effervesces with hydrochloric acid. Annabergite in the matrass yields water and becomes darker. B. B. fuses in the tip of the blue flame and tinges the outer flame light blue (arsenic). On coal in E. F. yields arsenical fumes and fuses to a blackish-gray globule of arsenide, which usually with borax in 0. F. shows nickel only. A borax bead highly charged on wire and then reduced beside lead on coal, when flattened is blue (Co) or violet (Go + Ni). With soda on coal occasionally yields the sulphur reaction. Arsenate of nickel. — Both varieties react like annabergite; the green variety is said to be infusible, B. B. The silicates above named generally yield much water and be- come black or dark green in the matrass. B. B. fuse only on thin edges. Dissolve rather easily in borax and S. Ph. showing nickel and silica. Imperfectly dissolved by soda; if the E. F. is employed, magnetic, metallic nickel is obtained upon washing away the slag. To detect the magnesia, lime, alumina, and trifling amount of iron in these minerals, they must be powdered and fused with soda, borax, and silver on coal in E. F. and further treated according to p. 128. Morennsite yields acid water in the matrass, swells up and hardens, becoming yellow and opaque. AVith borax and S. Ph. a distinct nickel reaction. The Eiechclsdorf mineral colors the outer fliime hlue, from the presence of arsefiic (Dana). A sulphur reaction is obtained with soda in E. F. On coal glows very etrongly and evolves much sulphur dioxide. ZINC. 209 c. Examination for nickel in metallurgical products. The mefliod of examining products for nickel has been given partly under the general examination for iron, p. 183, and partly under the description of products containing iron, p. 195. 6. Ziuc, Zn. Its occurrence in the mineral hingdom and in metallurgical products. Zinc occurs in nature under the following conditions: a. Combined with sulphur in Sphalerite {zinc Uende), yellow, green, red, brown, and black, very rarely colorless. The purest, colorless variety, Zn S, with 66.9 Zn. The colored varieties contain more or less sulphide of iron; the blackish-brown variety, from various localities, Fe S, 4 Zn S, with 54.5 Zn ; marmatite, or black blende, Fe S, 3 Zn S, with 51.5 Zn ; christophite, Fe S, 3 Zn S, with 46.1 Zn. A fre- quent constituent of sphalerite is Cd S; Mn S occasionally occurs, especially in the black variety, which not unfrequently contains tin; finally, sphalerite (the blackish-brown or brown variety) seems, thus far, to be the mineral in which indium especially.occurs. Von Kobell found thallium in some blendes. Huasoolite,— 3 Zn S + 2 Pb S (Domeyko). Wurtzite,— Zn S. Zinofahlerz (Kupferblende), vide copper. Stannite, vide tin. I. In a combination of sulphide with oxide. ' Voltzite,— Zn + 4 Zn S, with 69.2 Zn. c. As oxide in Zincite,— Zn 0, with 80.2 Zn; generally mixed with more or less Mn' 0', franklinite, or magnetite. d. As oxide combined with other metallic oxides in Franklinite, vide manganese. e. Combined with sulphuric acid in , Goslarite {zl7ic vitriol),— Zn S 0* + 7 H' 0, with 32.6 Zn, but 210 plattner's blowpipe analysis. often containing oxides of Mn, Fe, and Cu, with earthy mat- ters, as impurities ; Zincosite, Zn S 0' ; Gloekerite, vide iron. /. Combined with carbonic acid in Smithsonite, — Zn C 0% with 52 Zn, but in most varieties some Zn replaced by other oxides and by earths, viz., Fe 0, Mn 0, Cd 0, Cu 0, Pb 0, Ca 0, and Mg 0, so that the Zn C 0' may sink to 40 per cent. ; many varieties also contain intermixed calamine. Hydrozincite {zinc Uoom),—^ Zn 0, C 0" + 2 H' 0, with 57.1 Zn; Aurichalcite (huratite),—^ (Cu, Zn) O, 2 C 0' + 3 H^ O ; with 35.8 Zn and 23.2 Cu. Buratite contains a little Ca ; Iglesiasite {Zi7icUeispath},—G Pb C 0= + Zn C 0=, with 3.7 Zn and 71.8 Pb. g. Combined with arsenic acid in Kottigite from Schneeberg,— 3 Zn 0, As' 0' + 8 H' 0, with part of the Zn replaced by Co (6.9 per cent.) and Ni (3 per cent.). Adamite,— 4 Zn 0, As'' 0' + H' 0; usually some Co and Cu 0. h. With silicic acid in ATillemite, III, 1 G,— 3 Zn 0, Si 0% with 58. 1 Zn, but often con- taining a little Mn' 0', Fe' 0', Ca 0, and Mg 0; Troostite, II-III, 1 G, — willemite with part of the Zn replaced by Mn 0, and Mg 0; 46.5-53.7 Zn; Calamine (hydrous silicate of zinc) II-III, 1 G, — 2 Zn 0, Si 0' + ir 0, with 53.7 Zn ; Moresnetite,— 8 Zn C'Al^ Qs, 7 Si 0" + 9 H' 0, with 36.2 Zn, and containing 1.1 Ni ; Danalito, vidi- glucina; Stirlingite, vide iron. Oxide of zinc also forms a trifling ingredient in Jeffersonite, vide lime. i. Combined with alumina in Gahnite {automolite) III,— (Zn, Mg, Fe) 0, (Fe, Al)' 0', with 19.4 to 27.9 Zn; allied to it are kreittouite and dysluite (the latter richer in Fe' 0' and Mn 0). Zinc occurs in various metallurgical products: a. Metallic in Raio zinc, containing usually a little Pb, Fe, Cd; sometimes Sn, In, EXAMINATION- FOB ZINC. 211 The first portions distilled from cadmiferous ores are particularly rich in cadmium. i. Combined with sulphur in various products consisting of metallic sulphides, riz., iZoAsfetw, lead and copper matta, cadmia from the Mohofen and lead furnaces, when these products result from silver, lead or copper ores containing blende. c. As oxide, which collects at the commencement of the zinc distillation in the condensers, together with metallic zinc, as well aa during the further progress of the operation; the first portions are usually very rich in cadmium ; the oxide also is found in the slags and flue rakings produced by smelting roasted silver ores containing blende in shaft and reverberatory furnaces. Here is included also the cadmia (Gichtenschwamm) of the iron blast-furnaces, which sometimes consists of pure crystallized oxide ■of zinc, but frequently forms only a compact mass of oxides of zinc and iron mixed with earthy particles. Examination for Zinc, Including the blowpipe characteristics of the minerals mentioned above. a. General examination for zinc. The examination for zinc is very simple, as the metal is volatile, ■while its oxide is fixed in the 0. F., and is very certain in case the substance contains much zinc, or if containing little zinc is free from other metals or oxides, which are reduced on coal and form a coat. When, however, a very small amount of zinc is present with much lead, antimony, or bismuth, for example, it cannot always be ■certainly detected by the blowpipe. Substances containing much zinc, either as sulphide or oxiHe, are treated alone, but those containing only oxito" etc. *'* a little may be powdered and fused with suflBcient soda on coal in E. F.; generally, however, the latter will also afford a distinct zinc coat with a good E. F. alone. When the substance ia a combination of metallic oxides, or contains possibly some earths :n addition, a mixture of two parts of soda with one to one-and-a-half •of borax is employed. The zinc is thus volatilized as metal, but immediately oxidizes again and deposits on the coal a coat, which is yellow while hot and white when perfectly cold. This coat is espe- ■cially characterized by the green color which it assumes when moistened with cobalt solution, and ignited in 0. F., p. 91. If 212 PLATOrUEK'S BLOAVPIPE ANALYSIS. the substance contains much lead, the zinc coat, although not so far fi'om the assay as the lead coat, is usually rendered impure by oxide of lead. On moistening such a coat with cobalt solution and care- fully igniting it in 0. F., the oxide of lead is reduced by the glowing coal and volatilizes, leaving the oxide of zinc, which assumes a greeu color on cooling. Should the zinc coat be so thin that it is liable to be blown away after being moistened with cobalt solution, a decisive result may not always be obtained, and it is then better to moisten the coal where the zinc coat generally forms with the solution before treating the substance with the flame. A single drop spread out with a glass rod is suflBcient for detecting a little zinc. Since it m necessary to treat the substance for some time with the blowpipe flame the moistened spot is ignited at the same time, any oxide of lead or bismuth mixed with the oxide of zinc is removed, and the deposited zinc coat appears distinctly green when cold. A similar process may be used in case of a feeble coat already formed by moistening the latter, and then directing the flame not upon it, but directing the E. P. again upon the assay on the coal, whereby more zinc is volatilized, while the already moistened coat is ignited throughout. It must be borne in mind, however, that when the substance contains little or no zinc, but much antimony, and the coal is moist- ened before employing the blowpipe, a combination of cobalt with one of the acids of antimony will be formed, which likewise has a green color and cannot be driven off with the 0. F, p. 92. In this case a little zinc can only be found with difficulty before the blowpipe. With many compounds, however, as in antimonial tetrahedrite, it is possible first to volatilize nearly all of the antimony with the 0. F. and to remove the oxide of antimony from the coal by directing the flame upon it, after which the zinc may be detected by treating the residue in the E. F. as above. When tin is present zinc cannot be recognized by the coat formed on coal, as its oxide is then mingled with binoxide of tin, which assumes a bluish-green color with cobalt solution, p. 92. i. Behavior of the above-named zinciferous minerals before the blowpipe. COMPOUNDS OF ZIXC WITH SULPHUR. Sphalerite in the closed tube sometimes decrepitates with gi-eat violence, but yields nothing volatile and generally retains its color. EXAMIN^ATION FOR ZINC. 313 The ignited assay being strongly heated in the open tube evolves sulphnrous acid, and if heated for a sufBcient time appears yellowish or brownisb-red, according as it contains little or much iron. Treated alone in E. F. on coal it first yields a feeble, reddish - brown coat of oxide of cadmium, unless too little cadmium is present, but afterward a distinct zinc coat ; it is infusible. In 0. F. it roasts completely, but rather slowly, and then with borax readily shows whether much or little iron is present. With soda on coal it affords zinc and cadmium coats. Manganese, if present, is detected by testing the roasted powder with soda and nitre. Sometimes the coat from the mineral alone on coal shows, after a long and strong blast, a faint rose color {vide silver). THE COMPOUND OF SULPHIDE WITH OXIDE OF ZINC. VoUzite behaves like sphalerite containing only traces of iron. OXIDE OF ZINC. Zinciie {red-oxide of zinc) is infusible. With borax in 0. F. dissolves easily and shows manganese. The strongly saturated glass treated a short time in R. F. loses the manganese color and generally shows a yellow, or bottle-green, iron color. The glass on coal in E. F. affords a zinc coat. Treated on coal alone, or with soda, it affords a strong zinc coat; on platinum foil a manganese reaction. OXIDE OF ZINC COMBINED WITH ACIDS. Goslarite alone in the matrass yields water; with charcoal dust^ sulphurous acid. With the fluxes behaves like oxide of zinc and sometimes shows reactions for manganese, iron, and tjopper. It is decomposed with soda on coal, yielding a strong zinc coat and sulphide' of sodium, which sinks into the coal. Smitlisonite in the matrass yields carbonic acid and, if nearly free from other metallic oxides, is yellow while hob and white on cooling. The white mass reacts with the fluxes either for zinc alone, or also for iron. If considerable protoxide of iron and manganese are present the ignited mineral becomes quite dark, is magnetic and reacts strongly for iron and manganese with the fluxes. Cupriferous smithsonite imparts a lasting green tinge to the flame, even if very little copper is present. The copper can be detected readily with S. Ph. and tin. The unignited mineral dissolves readily with 214 plattneb's blowpipe analysis. effervescence in the fluxes. Alone, or with soda, on coal in K. F. it is decomposed, and with a sulSEiciently strong blast may even afford a zinc flame. At first only a cadmium coat is perceptible, but afterward zinc alone. Effervesces with hydrochloric acid, Hydrozincite yields water in the matrass, loses its carbonic acid and then behaves like oxide of zinc. Alone on coal in K. F. most of it is gradually volatilized, forming a strong zinc coat and leaving generally a trifling scoria, which, with borax, shows the iron reactions. Aurichalcite (buratite) yields water in the matrass, and the green (with buratite blue) color changes to black. Dissolves with effer- Tescence in the fluxes to a clear glass and shows copper. The glass on coal with tin becomes red and opaque on cooling, while a feeble zinc coat is obtained. With soda on coal in E. F. a strong zinc coat and a residue in which metallic copper can be detected by washing. The trifling amount of Ca in buratite is found by reducing the Cu and Zu on coal with soda and borax and a gold or silver button; most of the Zn volatilizes and the glass is then treated according to p. 138. Iglesiasite fuses in 0. F. on platinum foil to a clear yellow glass. With the fluxes it dissolves with effervescence to a yellowish glass, colorless on cooling, which affords a lead coat in K. F. on coal. Alone, or with soda, on coal it is reduced with effervescence to metallic lead and forms a lead coat, with a second white coat, near the assay, which assumes a green color with cobalt solution (zinc). Kottigite in the matrass yields much water. Fuses on coal in O. F. to a globule, which in R. F. evolves an arsenical odor, coats the coal with oxide of zinc, and is black when cold. In the forceps fuses easily to a bead, giving a strong, light-blue flame. Dissolves largely in the "fluxes, showing cobalt; the strongly saturated glass on coal in K. F. affords a zinc coat. With soda, or neutral oxalate of potassa, on coal in E. F. much zinc is reduced, forming a very strong zinc coat. Adamite, according to Dana, decrepitates feebly in the closed tube, yields a little water, and becomes white and porcelanous. On coal a zinc coat and feeble arsenic odor, and in the closed tube with soda and charcoal a ring of arsenic. With borax in 0. F. a pearl-yellow bead, colorless on cooling. EXAMIXATIOiNT FOR ZINC. 215 SILICATES OF ZINC. The hydrous silicate, calamine yields water and becomes milk- white in the matrass. B. B. the silicates of zinc are infusible. (According to Dana, willemite glows in the forceps and fuses with difficulty to a white enamel; the New Jersey varieties fuse from 3.5 to 4.) They dissolve in borax to a clear glass, that cannot be made opaque by flaming ; the clear S. Ph. glass becomes cloudy on cooling ; and when strongly saturated the still warm glass shows a little separated silica. They are not dissolved by soda alone on coal, but swell and afford a zinc coat with difBculty. With two parts soda and one borax, however, all of the zinc is reduced and volatilized, while the silica fuses with the flux to a glass, which with borax in 0. P. sometimes shows iron. Any lead present will cause a slight lead coat behind the coat of oxide of zinc. Silica and the earths present may be found by treating the glass in the wet way. With Boda and nitre a manganeSe reaction is occasionally obtained. COMPOUNDS OF OXIDE OF ZINC WITH ALUMINA. Galmite {auiomoliie) is unchanged in the matrass and forceps. Even the fine powder dissolves with extreme difficulty in borax and S. Ph., without showing iron distinctly. It only forms a dark slag with soda, but dissolves readily in a mixture of equal parts of borax =ind soda, yielding a vitriol-green glass and a distinct zinc coat, if the E. P. is strong enough. With soda and nitre gives a manganese reaction. Kreittonite behaves like gahnite, but with the glass fluxes dissolves with difficulty and shows a notable amount of iron. To detect alumina and magnesia the glass obtained by treating the mineral with soda and borax is pulverized in the steel mortar and further treated in the wet way. c. Examination for zinc in furnace products. The method of testing the products above mentioned, both for zinc and other constituents, may be deduced partly from the general examination for zinc, p. 211, et seq., and partly from the remarks on products containing iron and zinc, p. 196. 216 plattnek's blowpipe axalysis. 7. Cadmium, Cd. Its occurrence in the mineral kingdom and in metallurgical products. Cadmium belongs to the rarer metals and occurs : a. Combined with sulphur in Greenockite, — Cd S with 77.6 Cd. Sulphide of cadmium occurs as an accessory ingredient in certain Tarieties of sphalerite. S. As oxide combined with carbonic acid in Smithsonite, in which it forms only a minor, accidental ingredient, vide zinc. In metallurgical products cadmium occurs particularly in the oxide of zinc and dust {Zinkstaui) which pass oyer first during the distillation of zinc from ores. Examination for Cadmium, Including the blowpipe characteristics of cadmiferous minerals, a. General examination for cadmium. Cadmium can only be detected as oxide by the blowpipe, owing to its volatility. The substance is treated for some time with the R. F. on coal, when the cadmium is volatilized as metal, but oxidizes at once in contact with the air. The oxide is mostly deposited on the ooal and when cold may be recognized by its brown color, which, however, is only orange-yellow in thin layers, p. 68. When there is very little cadmium and the coat cannot be easily obtained the powdered substance should be mixed with soda and treated a very short time in R. F.; a more distinct cadmium coat is then obtained. Zinc ores containing cadmium give a white coat with a brown edge, cadmium being more volatile. In blowing too long some zinc is also volatilized and its oxide some- times renders the cadmium coat less distinct. b. Blowpipe characteristics of cadmium minerals. GreenocMte feebly heated in the closed tube assumes a transient carmine-red color. In the open tube it yields sulphurous acid. Alone on coal it affords a distinct coat of oxide, and with soda a very abundant reddish-brown coat, while most of the soda sinks into the coal, and evolves an odor of sulphuretted hydrogen whoij moistened. For sphalerite and smithsonite, vide zinc. LEAD. 217 8. Lead, Pb. Its occurrence in the mineral hingdom and in metallurgicai products. Lead is quite widely distributed in nature ; it occurs : a. Metallic in Native lead, — Pb. i. Combined with tellurium in Altaite, — Pb Te, usually mixed with Ag' Te and containing G1.7 Pb; varieties from California and Colorado contain also gold telluride. Nagyagite (and Weisstellur), vide gold. c. Combined with selenium in Clausthalite, — Pb Se, with 72.3 Pb, sometimes containing some Ag,. or a little Co, Cu, Hg, and Fe ; Tilkerodite,— Co Se^ + 6 Pb Se, with 64.2 Pb and 3.1 Co, but not quite free from Fe; it is retained under clausthalite by Dana ; Zorgite {Seleribleikupfer and SelenkupferWei] ; compounds of Cu" Se and Cu Se with Pb Se in varying proportions ; the lead varies from 16.5 to 65.1 per cent, and the copper from i to 46.4 ; Lehrbaohite, — a mixture of Hg Se and Pb Se in very variable proportions, with 55.5 to 62.1 Pb ; Selenquecksilberkupferblei, questionable compounds of Pb Se, Cu' Se, Cu Sb, Hg Se, with 16.1 to 43 Pb. d. Combined with sulphur in Galenite {galena), — Pb S with 86.6 Pb, but frequently containing a little Ag' S, Sb' S', Fe S, and Zn S; Bleischiveif, or compact galena, frequently contains Sb" S', and perhaps Zn S; Steinmannite is impure galena ; so-called Johnstonite contains admixture of sulphur; Geocronite, — 5 Pb S + Sb" S'. A little Cu and Fe is present; Kilbrickenite,— 6 Pb S + Sb" S', with 70 Pb, and a little Fe; Meneghinite,— 4 Pb S + Sb' S', with 64 Pb; but some Cu' S and Fe S seems to be mixed with it; Boulangerite {embrithite, plumbostib)*, — 3 Pb S, Sb' S', with 53.9 Pb and a little Fe, Cu, and Zn; Epiboulangerite,— 12 Pb S + Sb' S= + 3 Sb' S\ with 55.5 Pb and a little Fe, Ki, and Zn ; Dufrenoysite,— 2 Pb S + As' S', with 57.1 Pb and a little Ag, Cu, and Fe ; the combination Pb S + As' S' also occurs, called shleroMas {sartorite, Dana) ; * Embrithite and plumbostib are perhaps 10 Pb S + Sb" S», with 60.7 Pb. 218 plattner's blowpipe analysis. Jiimesonite {feather ore, heteromorphite, plumosite), — 3 Pb S + Sb' S% with 50.6 Pb; almost always some Cu, Fe, or Ag replacing Pb, and some Bi replacing Sb; Plagionite,— 9 Pb S + 7 Sb= S' (?), with 41.9 Pb; Ziukenite,— Pb S + Sb" S', with 35.7 Pb and traces of Cu; Ziindererz, probably a mixture oijamesonite {feather ore), dufren- oysite, arsenopyrite and red silver ore ; Jordanite — 4 Pb S + As" S', with 68.8 Pb; Clayite, probably a mixture of tetrahedrite with other minerals (Naumann-Zirkel), contains S, As, Sb, Pb (68.51), Cu, Ag (trace), Dana. Cuproplumbite,— 3 Pb S + Cu'' S, with 64.9 Pb and 19.9 Cu; Alisonite,— 3 Pb S + 3 Cu'' S, with 38.9 Pb and 53.3 Cu; Bournonite,-3 Pb S + Cu' S + Sb'' S', with 43.3 Pb and 13 Cu; Cosalite,— 3 Pb S + Bi= S', with 41.6 Pb and 43.3 Bi; Kobellite,— 3 Pb S + (Bi, Sb)= S=, with 54.3 Pb and 18.1 Bi, also admixture of Cu and Fe ; Aikinite (acicular iismuth),— 2 V\> 8 + Ca' 8 + Bi' S>, with 3fi.l Pb, 36.2 Biand 11 Cu; Chiviatite,— 2 Pb S 4- 3 Bi' 8', with 17.2 Pb, 61.3 Bi and 2.4 Cu which replaces some Pb ; Freieslebenite, Weissgiltigerz (part), brongniardite, vide silver. e. Combined with chlorine in Cotunnite, — Pb CF, with 74.5 Pb; laurionite contains also Pb and IP 0; Mendipite,— Pb QY + 3 Pb 0, with 85.8 Pb and sometimes a little Pb C CandH" 0; Matlockite,— Pb CP + Pb 0, with 83 Pb; Phosgenite {corneous lead),—Fh CP + Pb C 0', with 73.8 Pb; Nadorite,— Pb GV + Pb 0, Sb' 0'; Percylite,— Pb CP, Cu CP, Pb 0, Cu 0, H' 0. /. With chlorine and iodine in Sleioxwodch.lorid,—2 Pb 01" + Pb 1= + 5 Pb ; Schwartzembergite is probably similar. g. As oxide in Massicot, — Pb 0, with 93.8 Pb, but often mixed with more or less Pb C 0' and Fe' 0'; Minium,— Pb» 0', with 90.6 Pb ; Plattnerite,— Pb O^ with 86.6 Pb and occasionally traces of 8 0>. h. Combined with acids : a. With sulphuric acid in Anglesite,— Pb S 0*, with 68.3 Pb ; Linarite,— Pb 8 0* + Pb + Cu 8 0' + Cu O + 2 H" ; with 51.7 Pb and 15.7 Cu ; Caledonite, perhaps E 8 0' + E ; B = Pb and Cu, with 63.5 Pb and 5.8 Cu ; LEAD, 219 Lanarkite,— Pb S 0« + Pb 0, with 78.7 Pb ; LeadhiUite,— 7 Pb O, 4 C 0=, 2 S 0' + 2 H" O, with T5 Pb. 13. With phosphoric acid in Pyromorphite,— 3 Pb= P' 0» + Pb CF, with 76.3 Pb; occasionally some P' 0' is replaced by As' 0"; part of the Pb by Ca 0, and some Pb CP by Ca ¥'; such varieties are polysphcerite, miesite, and nussierite; Plumbogumraite, varying proportions of Pb 0, Al'' 0", P" 0", and H' ; Beudantite, vide iron. y. With arsenic acid in Mimetite,— 3 Pb= As' 0" + Pb or, with 69.5 Pb. Isomorphous mixtures of this combination with the corresponding phos- phates and analogous lime compounds also occur. Hedyphane is such a variety containing 49 Pb. Gampylite contains a little lead chromate. Carminite, vide iron. 6. With carbonic acid in Cerussite,— Pb C 0\ with 77.6 Pb; Earthy carbonate ot lead (erdiges Weisshleierz), with a little Ca and H» ; Plumbooaleite, tarnoTieite, vide lime ; iglesiasite, vide zinc. e. With selenoiis acid in Kerstenite— Pb 0, Se 0^ (Cu and Pe'' 0=). C. With chromic acid in Phcenicochroite ,— 2 Pb Cr 0* + Pb 0, with 70.8 Pb; Crocoite,— Pb Cr 0\ with 63.3 Pb ; Vauquelinite,— 3 Pb 0, Cu 0, 3 Cr 0=, with 56.4 Pb and 8.6 Cu; Laxmannite,— 2 E Cr 0* + E' P'' O" ; E = Pb and Cu. Phosphochromite is proDably identical with this mineral. 1]. With vanadic acid in Descloizite {vanadite), — 4 Pb 0, V 0", with 63 Pb, but containing some Zn 0, Cu 0, Mn 0, Fe 0, CI, and H' 0; Dechenite,— Pb 0, V 0=, with 50.7 Pb; Vanadinite,— Pb CP + 3 Pb' V 0', with 73 Pb. The varieties from Windischkappel and Beresof contain P' 0' and may be regarded as isomorphous mixtures of pyromorphite with the above ; Eusynchite,— 4 Pb^ T^ 0^ + 3 Zn' V O", with 53.5 Pb ; some Cu is present, and a little ¥2 0= is replaced by As" 0' and P^ 0= ; tritochorite is similar ; Arseoxene,— 3 (Pb, Zn) 0, V^ 0» + 3 (Pb, Zn) 0, As= Qs, with 47.4 Pb. d. With molyMic acid in Wulfenite,— Pb Mo 0*, with 57 Pb, and occasionally a little Cr 0' and V 0\ In the red variety from Phcenixville, as well as in the so-called eosife, are larger quantities of the latter acid. According to Domeyko there is a variety — 3 Pb Mo 0* -(- Ca Mo 0*. 220 plattnek's blowpipe analysis. I. With tungstic acid in Stolzite,— Pb W 0* with 44.9 Pb, sometimes with Ca 0, Fe 0, and Mn 0. K. With antimonic acid in Bindheimite (Bleiniere) from Nertschinsk, — 3 Pb 0, Sb' 0° + 4 H^ 0, with 57.3 Pb. The Horhausen variety— 3 Pb 0, Sb' 0' + 3 H= 0. Similar varieties are monimolite, partzUe, coronguite, OehroUte,— 3 Pb O, Sb" 0» + Pb O + 2 Pb CV. A. With antimonous acid in Nadorite, cf. lead chlorides. . Lead occurs under various conditions in metallurgical products obtained in the treatment of plumbiferous ores: a. Metallic in Various sorts of lead which are met in commerce, but occasionally contain more or less Cu, Sb, As, Ag, Bi, Sn, Zn, Ni, Fe, and S. Slack copper, which is extracted from plumbiferous copper mails and frequently contains several metals besides Cu and Pb, vide iron. b. Combined with sulphur in the various matt-like products obtained in smelting lead ores, or plumbiferous silver ores; also in lead speiss and in plumbiferous cadmia, vide these products, under iron, p. 182. " c. In the state of oxide in Litharge— Pb 0, sometimes containing a little Bi' 0', Cu 0, Ag' 0, 5 0^ and disseminated portions of the mass of the furnace; Abstrich, — Pb 0, mixed with basic stannate, antimonate, and arsenate of lead ; Lead smoke, or fumes, containing Pb 0, Pb C 0', Pb S 0*, Pb' As' 0°, Pb' Sb' 0', Pb, Pb Si 0', etc.; d. As oxide, usually combined with silicic add, in the variooa ilags produced in smelting plumbiferous charges. Ezammation for Lead, Including the blowpipe characteristics of the minerals and metal- lurgical products above mentioned. a. Examination for lead in general. Id alloys, as they occur in nature and metallurgical products, lead is recognized by the coat which it aflfords when the ^'' substance is treated on coal in 0. F. Any easily volatilizable EXAMINATION FOE LEAD. 221 metals present either pass oflf entirely in fumes, or collect also in a coat as oxides. The oxide of lead coat is dark lemon-yellow while hot and straw-yellow when quite cold, p. 68, and being also nearer the assay than that formed by some other oxides, as those of tellu- rium, antimony, and arsenic, is therefore readily distinguishable ; it must be remarked, however, that in presence of antimony the oxide of lead coat is darker yellow, like the bismuth coat, probably ia consequence of the formation of antimonate of lead, vide sulphide^ on the following page. If zinc and lead are present in an alloy the coat produced is, indeed, mingled with oxide of zinc, but the lead may be recognized by the sulphur-yellow color of the cold coat as well as by the azure- blue tinge imparted by it to the E. F. When the lead predominatea in an alloy of lead and bismuth, the coat appears rather darker than a pure lead coat, but not so dark as a bismuth coat. By testing with S. Ph. the presence of bismuth can be ascertained, vide bismuth, provided no antimony is present. Should there be so little lead that it cannot be recognized by the color of the coat, the latter is treated with the E. F., in order to ascertain whether it disappears with an azure-blue flame, which, in the absence of selenium, indicates lead. If selenium has been found by testing in the open tube, it can be driven off by a feeble blast on coal before the lead volatil- izes. Combinations of lead with sulphur and other metallic sulphides may be variously examined for lead. The simplest way is to treat a small portion in E. F. on coal, either alone or with a slight amount of borax to separate any iron present, and to recognize the lead by the coat. Unless a large amount of antimony is present it could not be simultaneously detected with certainty, because adjoining the yellow oxide of lead coat there is formed a white coat of sulphate of lead, which very closely resembles oxide of antimony, p. 69. It is safer in this case to mingle the powdered substance with a sufficient amount of soda and treat it for a short time in E. F. Sulphide of sodium is formed and in the absence of antimony only a yellow lead coat with a bluish-white border ia produced; but if antimony is present a white coat of oxide of antimony is obtained beyond the yellow lead coat. Should the amount of antimony be very trifling, as in many galenas, this method does not afford a perfectly reliable result, because by a prolonged blast some sulphide of sodium is volatilized and also affords a white coat of sulphate of soda, p. 69. A little antimony can, however, be detected with absolute certainty whea 223 plattnee's blowpipe analysis. present in galenas and other sulpiides consisting mainly of sulphide of lead, by the following process. About fifty milligr. of the pow- dered substance are placed, with a bit of iron wire as stout as a coarse knitting needle, in a cylindrical cavity bored in the cross section of a good coal, or in a charcoal crucible, and both are covered with a mixture of soda and borax, the volume of soda being Uvici and that of borax once the volume of the substance employed. The whole is then treated in E. F., until all the sulphur is separated, part being combined with the iron and part with the slag. The lead is nearly all reduced and unites to a button with the antimony, while but little of them is volatilized. The cold lead button is then separated from the slag and the iron sanoanded by sulphide of iron, and is treated with a little soda in 'R.V. on another 3oal, when the antimony volatilizes first, producing a coat of oxide, and the lead aftervviird vields a lead coat. If the anvinovj coat if touched with the E. F., before a distinct lead eoat has formed, it disappears with a greenish-blue flame. The coat of oxide of lead can also be entirely prevented by adding vitrified boracic acid to the antimonial lead, when the acid takes up the oxide of lead and the volatilizing antimony coats the coal with oxide of antimony. This assay is easy, but the following points should be carefully observed. The separation of the sulphur from the lead and antimony must be conducted in a rather deep cavity, so that the antimonial lead may be protected from the air and as little antimony as possible volatilized- The flame must not be directed immediately upon the separating metallic button, which would then be too strongly heated and might lose antimony by volatilization, but must be directed only upon the slag of soda and borax, which should be made to cover the button. If carefully conducted quite a trifling amount of antimony may be detected by the coat formed on coal. When the amount of antimony in a substance containing sulphide of lead is very large, the treatment with soda alone, as well as of the antimonial lead reduced by iron, yields not only an unmistakable antimony coat, but the lead coat is observed to have a darker yellow color than usual. It appears orange-yellow while hot, and almost lemon-yellow on cooling, quite like a coat of oxide of bismuth.. Antimonate of lead seems to be formed, for if this coat is scraped off, dissolved in S. Ph. on platinum wire in 0. F., and the bead shaken off and treated with tin on coal, it assumes on cooling a. black color and becomes quite opaque, which, in the absence of bismuth, indicates antimony. Lead may also be detected in metallic sulphides by roasting them. EXAMINATION FOB LEAD. 233 in fine powder, p. 78, and then treating them with soda in E. F. Either globules of lead result, or an alloy of lead with other metals, in presence of other easily reducible oxides. A lead coat is likewise formed, to which regard must be had, especially if but little lead is present. If the roasted substance contains much copper the reduction with soda affords an alloy, in wliich the lead cannot be recognized oy the color, but after washing the alloy and keeping it fused for some time alone in a strong 0. P. on coal, most of the lead vola- tilizes and affords a coat. The copper can be found by S. Ph, The behavior of chloride of lead has been given on p. 69. Substances containing oxide of lead with other metallic oxides or earths usually yield a distinct lead coat when treated alone on ,. -n -A ■,-,•,• n 1 T T ■, Oxides. coal in K. F.; addition of soda, however, renders it more distinct. The same remark applies to all salts of lead except the phosphate, which treated alone on coal fuses to a globule and affords no lead coat, or only a slight one. i. Blowpipe characteristics of the above-named plumbiferous minerals. Native lead behaves B. B. like pure lead, p. 67. Altaite yields in the open tube tellurous fumes, wliich fuse B. B. to clear drops, (G. Eose.) On coal it fuses, tinges the fiame greenish-blue and Tolatilizes, leaving a smaU silver button. Clausthalite in the closed tube decrepitates occasionally, but suffers no further change. In the open tube yields a selenium sublimate, red at a distance from the assay and steel-gray nearer to it ; a distinct selenium odor is perceptible. On coal it fumes, dif- fuses a strong selenium odor and fuses only imperfectly in E. P., coating the coal at first with a gray coat of selenium, having a feeble metallic lustre, but appearing reddish further from the assay. A distinct lead coat forms afterward. It gradually volatilizes, leaving ft very trifiing scoria, which sometimes affords iron, cobalt, or copper reactions with the fluxes. With soda, or, better still, neutral oxalate of potassa, in E. P. on coal, metallic lead is obtained, which sometimes yields a small silver button on the cupel. Tilkerodite behaves like clausthalite, -but the remaining scoria reacts very strongly for cobalt. Zorgite. — SelenkupferUei behaves like clausthalite, and the remain- ing scoria reacts very strongly for copper with borax, while with 224 plattnek's blowpipe analysis. soda it yields a copper button. SehnUeikupfer fases easily, spreads over the coal and forms a gray mass, with a metallic lustre, which after thorough roastiag yields a copper button with borax and soda, (Berzelius.) Lehriachite alone in the matrass yields a lustrous, metallic, crys- talline, gray sublimate of selenide of mercury, before which a few globules of mercury sometimes collect. With much soda it yields only mercury. In the open tube yields some selenium and a sub< limato of selenide of mercury, which fuses to drops. On coal, like claustbalite. Selenquecksilberkupferblei (Hg, Cu, Pb, and Se) yields in the matrass selenide of mercury. On coal aflfords a lead coat and a residue which reacts strongly for copper. Lead in combination with sulphur and wiih other metallic sulphides. Galena and Bleischweif usually decrepitate strongly in the closed tube, while a trifling white sublimate is not unfrequently formed, which, however, appears to be only sulphur. In the open tube yield sul- phurous acid and at a higher heat a white sublimate of sulphate of lead, gray just above the assay. Fuse with difficulty on coal, until most of the sulphur is expelled, when metallic lead separates. The coal is strongly coated with salphate and oxide of lead. In presence of antimony the sulphate coat is mingled with oxide of antimony, p. 222. Iron and zinc in galena are found according to pp. 184 and 212. More or less silver may be detected in most galena by cupel- ling the lead reduced on coal, vide quantitative silver assay. Joliiistonite behaves like galena, but gives a considerable sulphur sublimate. Geocronite, kilbrickenite, menegliinite, boulangerite, jamesonite, feather ore, plagionite, zinkenite, etc., are compounds of Pb S with Pb S, Sb° S' in different proportions. The general behavior of these minerals is as follows : — In the closed tube they decrepitate more or less and are distin- guished by their fusibility when the tube is treated B. B. Those containing most sulphide of antimony, are the most fusible, and they, afford a red sublimate of amorphous tersulphide of antimony, con- taining oxide of antimony. In the open tube they yield antimonial fumes, partly volatile and partly fixed. The former consist of oxide of antimony; the latter partly of oxide with antimonic add, partly of sulphate of lead and partly of antimonate of lead, near the assay. Much sulphurous acid is also evolved. LEAD WITH SULPHUR AND METALLIC SULPHIDES. 225 On coal they fuse and deposit thick coats; the farthest removed are white and consist of oxide of antimony with sulphate of lead, while near the assay the coat is chiefly oxide of lead, but dark-yellow and mixed witK antimonate of lead. Any trifling amount of iron and copper usually remains as a scoria and can be tested after expelling the Pb and Sb. *. "With soda in R. P. they are decomposed and yield metallic glob- ules and coats of lead and antimony. To determine whether the white coat consists only of Sb' 0' or whether it also contains lead sulphate, vide p. 321. Arsenic, if not in too small quantity, can frequently be detected in the tubes and on coal by its characteristic behavior. Dufrenoysite {Binnit) decrepitates feebly in the closed tube, and then yields a red sublimate of sulphide of arsenic; in the open tube a smell of sulphur, with a coat of lead sulphate, and a sublimate of arsenous acid. On charcoal fuses very easily, evolves sulphurous and arsenous fumes, and finally yields a lead button. Sartorite, nearly like dufrenoysite; jordanite, similar, but fuses less easily and does not decrepitate. The behavior of Zundererz may be easily inferred from that of similar compounds. Clayite. — As regards the blowpipe characteristics it is only known that is fuses readily, yields reactions for lead, arsenic, and antimony, and leaves with soda a lustrous metallic globule; dull on cooling. Ko doubt after treatment with boracic acid, vide copper assay, the remaining button would afford copper reactions. Cuproplunibite. B. B. in the open tube swells up and fuses, aflbrd- ing sulphurous acid and a trifling sublimate of sulphate of lead. Alone on coal in E. F. yields coats of oxide and sulphate of lead ; with soda a button of metal, somewhat harder than pure lead, which after treatment with boracic acid, vide copper, leaves a copper button. This cupelled with test lead affords some silver also. Alisoniie; like cuproplumbite. NagyagiU, vide gold. — This mineral strongly heated in the open tube fumes and deposits a coat, which is gray close above the assay and seems to consist of tellurate, antimonate, and perhaps sulphate of lead. The coat further removed consists partly of volatile oxide of antimony, and partly of tellurous acid, which can be fused to clear drops. Alone on coal it fumes and deposits a white, volatile coat of mingled oxide of antimony, tellurous acid and sulphate of lead, and 226 plattjstbe's blowpipe analysis. a less Tolatile, yellow coat, consisting chiefly of oxide of lead, with perhaps some antimonate. The first coat disappears under the R F. with a bluish-green, the latter with a blue flame. When all the volatile ingredients are expelled a malleable gold button remains, which assumes a pure gold color when cupelled with test lead. K the flame test does not show tellurous acid distinctly in the white coat on coal it is only necessary to treat the powdered mineral with boracic acid, p. 309, when a coat of oxide of antimony and tellurous acid will be obtained, which will disappear with a bluish- green flame in R. F. Bournonite in the closed tube, when it is quite strongly heated, yields a slight dark-red sublimate of sulphide with oxide of antimony. In the open tube evolves sulphurous acid and copious, white, antimony fames. The coat condensing on the upper side of the tube is' volatile oxide of antimony ; that on the lower part is a non-volatile com- pound of antimonate of antimony with considerable antimonate of lead. Alone on coal fuses very easily, afibrding a coat of oxide of antimony, quickly followed by lead antimonate, sulphate and oxide, so that nearest the assay the coat is dark-yellow. Finally only a lead coat is afforded. The remaining globule tested with borax or S. Ph. shows copper and sometimes antimony, p. 221. It is rendered somewhat brittle by sulphur and antimony, and after cupellation occasionally affords a little silver. Kdbellite fased in the closed tube B. B. yields a slight sublimate of sulphur. In the open tube yields copious antimonial fames and sulphurous acid ; it is not fused, but is covered with yellow oxide. On coal fuses easily, yielding a white coat of oxide of antimony with sulphates of lead and bismuth, and a yellow coat, which is dark pomegranate-yellow on cooling and disappears with a feeble blue flame in E. F. Small, somewhat malleable, metallic buttons remain, which after being fused together for some time in 0. F., show copper, with S. Ph., vide copper. Freed from most of its sulphide of antimony on coal in 0. F., the mineral shows iron when treated with borax in E. F. and the glass remelted in 0. F. on platinum wire. The bismuth is found by roasting the mineral on coal and fusing the fine powder with potas- sium iodide and sulphur, vide bismuth. Aikinite in the open tube yields white fumes, partly fusible to clear drops, white on cooling; sulphurous acid is evolved. The remaining button is surrounded by black, fused oxide, which is transparent and greenish-yellow on cooling. LEAD — WITH CHLOEIlirE — OXIDES. 227 On coal fuses, fumes and deposits a white coat, the inner edge of which is yellow. The resulting button resembles bismuth (Ber- zelius). The coat is reduced in the inner flame without flame color- ation. Chiviatite. — Like aikinite, LEAD COMBINED WITH CHLOKINB. Gotunnite fuses to a yellow fluid and partially sublimes in the matrass. On coal fuses yery easily, spreads out and TOlatilizes, form- ing a white coat of chloride of lead. This disappears with an azure- blue flame in E. F. and leayes a yellow spot of oxide of lead. With soda yields lead and with oxide of copper afibrds the chlorine reaction, vide chlorine. Mendipite decrepitates, becomes yellow, and when strongly heated behares like cotunnite. On coal fuses easily, emits acid vapors and is reduced to metal, affording also a white coat of chloride and a yellow coat of oxide of lead. A special test shows chlorine. Matlockite. — Like mendipite. Phosgenite behaYCS like mendipite, but eflerresces with nitric acid. Nadorite decrepitates in the matrass and gives a white sublimate. On coal at first a lead chloride coat, then lead oxide and antimonate, finally metallic lead. The chlorine is detected by a bead of S. Ph. containing copper oxide, vide chlorine. Percylite decrepitates in the matrass; the blue color by gentle heating changes transiently to green; yields little water; finally melts to a brown fluid mass. In the forceps gives a green flame with a blue tip; on coal in inner flame yields buttons of copper and lead; the same with soda. OXIDES OF LEAD. Massicot {plumbic ochre), minium, and plattnerite fuse on coal and are reduced to lead ; color the flame blue when touched by it. OXIDE OF LEAD COMBIITED WITH ACIDS. Anglesite decrepitates in the matrass and usually yields a little water. On coal in 0. F. fuses to a clear bead, opaque on cooling, and in E. F. is reduced with effervescence to a lead button. Eeduced with soda yields lead, and a strong sulphur reaction is afforded by cutting out the coal and laying it on moistened silver foil. Trifling 228 plattn'er's blowpipe analysis. admixtures of oxide of iron or manganese may be easily detected by the tests with borax on soda and nitre. Linarite yields some water and loses its blue color in the matrass, On coal fuses in 0. F. to a bead; in E. F. is reduced with efferres- cence to lead, which then affords a lead coat. The lead button treated with boracic acid yields a button of copper, p. 251. Reduced with soda it yields copper and lead, while the alkaline mass that rinks into the coal gives a sulphur reaction. Caledonite. — B. B. on coal easily reduced. Partially soluble with effervescence in nitric acid, leaving a residue of sulphate of lead. Dana. The copper and also the sulphuric ac;d may be detected as in linarite above. Lanarkite. — Like caledonite, but no copper. In 0. F. fuses to a bead, white on cooling and containing reduced lead. Leadhillite swells a little on coal in a feeble flame, and assumes a transient yellow color ; in a stronger flame is easily reduced. (Fuses at 1.5. Dana.) Effervesces with nitric acid and leaves a residue of Pb S 0*. PyromorpMte sometimes decrepitates in the matrass, and strongly heated affords a trifling, volatile sublimate of Pb CI'. In the forceps fases very easily to a globule and affords a blue flame with a green tip (phosphoric acid), especially when the blast is gentle. The fused portion has a crystalline surface. On coal at first yields a slight coat of Pb Cr and the fused button is not reduced, but on cooling glows again and shows quite lustrous facets. The Pb 01' coat meanwhile increases and a pale yellow oxide of lead coat can be seen around the assay. If, however, arsenate of lead is present, it is reduced with effervescence and emission of arsenical fumes to lead, which remains with the crystalline phos- phate. The powdered mineral fused with oxide of copper on coal gives an azure-blue chloride of copper flame. By reduction with soda it affords lead, which sometimes yields a trace of silver when cupelled. Fused in the platinum spoon with three to four parts of bisulphate of potassa, it forms a clear mass, white on cooling. (Vanadate of lead affords a pomegranate-yellow mass, and chromate of lead a mass, which is violet while hot and greenish-white on cooling.) Mimetite fuses on coal somewhat less easily than pyromorphite, but is then reduced, with effervescence and a strong arsenic odor, to lead. At first affords only a chloride of lead coat, but later arsenous acid and oxide of lead. The presence of phosphate causes the LEAD — OXIDES AVITH ACIDS. 229 appearance of one or more of the crystalline beads aboye mentioned. Chlorine is detected as under pyromorphite. Lime (as in hedyphane) is found by decomposing the mineral with soda. The lead separates as metal, part of the soda sinks into the coal, and part forms with the lime an infusible mass. Plumlogummite decrepitates and yields much water in the matrass. Tested afterwards in the forceps it swells like a zeolite, and colors the flame azure-blue, but fuses only imperfectly. On coal cannot be melted, but gives a faint white coat of Pb CI.* In the fluxes dissolves easily to a clear glass ; the S. Ph. bead is opaque with a large addition. With soda yields lead globules and with cobalt solution turns blue. With boracic acid and iron gives a phosphide of iron, vide phosphoric acid. Cerussite decrepitates in the matrass, loses carbonic acid and turns yellow, with a stronger heat dark-red, but the yellow color returns on cooling. Alone on coal is easily reduced ; in the fluxes it dissolves with efiervescence and gives the reactions of oxide of lead. Dilute nitric acid also dissolves it with effervescence. Earthy carionate of lead. Like cerussite, but leaves on reduction a trifling scoria, which reacts for iron with borax. Kerstenite decrepitates slightly in the closed tube, fuses at redness to a black fluid mass and gives off a very little selenium ; at a higher heat some selenous acid. On coal fuses very readily to a black slag, evolves a strong selenium odor and affords lead buttons. The assay is surrounded by a lead coat and beyond this a selenium coat. With the fluxes gives reactions for iron and copper. Kersten. Phmnicochroite (melanochroiie) fuses readily in 0. F. to a dark mass, assuming a crystalline structure on cooling. In E. P. gives off lead fumes and is decomposed into sesquioxide of chromium and metallic lead. With the fluxes gives chromium reactions. Crocoite decrepitates and flies into small bits, assuming tran- siently a darker color. On coal fuses, spreads out and is suddenly reduced with deflagration to lead, affording also a lead coat, while grayish-green sesquioxide of chromium remains with the lead. Dissolves easily in the fluxes in 0. P. to yellowish glasses, becom- ing green on cooling. In E. P the green is darker. Eeduced with soda yields lead, and when fused on platinum foil with soda affords a dark-yellow mass, becoming hght-yellow when cold. Fused in the platinum spoon with three to four parts of bisulphate of potassa, a quite dark-violet mass results, which ig reddish on solidifying and when cold is greenish-white. (Vanadate of lead imparts a yellow color to the salt.) 230 plattnee's blowpipe analysis. Vauquelinite. — B. B. on coal swells a little and then fuses with frothing to a gray, lustrous, metallic globule, showing reduced but- tons of metal where it is in contact with the coal; a distinct lead coat is formed. With the fluxes gives in 0. F. green beads, both hot and cold; the borax bead on coal in R. F. gives an alloy of copper and lead, and a glass showing chromium. With tin on coal the S. Ph. bead is opaque red. Dissolves with eflfervescence in soda on platinum wire in 0. F., giving a clear green glass, yeUow and opaque on cooHng. This forms a yellow solution with water, in which chromic acid can be detected, vide chronium. It is completely reduced with soda on coal, and by treating the lead buttons, after washing away the coal, etc., with boracic acid, copper is obtained, vide copper. Descloizite in the matrass yields some water. B. B. fuses, is par- tially reduced to lead, surrounded by a black slag, and gives a lead coat. With borax in R. F. a green glass; in 0. F. a yellowish-red glass. With S. Ph. in 0. F. a yellow, in R. F. a chrome-green glass. With soda and nitre shows manganese. Dechenite fuses easily to a yellow glass in the forceps, and also in the matrass, without decrepitating. On coal fuses readily to a yellowish-green bead, and gives the usual lead globules and coat. In several assays a distinct arsenical odor was observed, but not in othera made with pure, transparent fragments. Phosphoric acid cannot be detected. The glass fluxes afford only vanadic acid reactions. Soda causes a white enamel, showing lead globules. Bergmann. Vanadinife from Zimapan decrepitates in the matrass, and at a high heat gives a trifling white sublimate. On coal in 0. F. the powder fuses easily to a black, somewhat lustrous mass, which yields lead in R. F. At first a slight Pb CV coat is formed, later of oxide of lead. Sometimes an arsenic odor. Dissolves readily in the glass fluxes, showing vanadic acid reac- tions, pp. 83 and 85. With soda in 0. F. on platinum wire fuses to a yellow mass, crystalliae and lighter in color when cold. On coal a lead button separates. Chlorine is detected by the S. Ph. bead con- taining oxide of copper. Fused in the platinum spoon with three to four parts of bisulphate of potassa, it forms a clear, yellow, fluid salt, assuming a red and finally a pomegranate yellow color on cooling, thus differing at once from crocoite and pyromorphite. LBAD IN METALLURGICAL PRODUCTS. 231 Wulfenite decrepitates in the matrass and transiently assumes a darker color. On coal fuses to a slaggy mass and from this lead separates and a lead coat is formed. Dissolves readily in borax in 0. F. to a clear yellow bead, colorless on cooling, which becomes opaque black in R. F. This, if presseu flat, appears dirty-green, with black flocks of binoxide of molybde- num, especially on coal. In S. Ph. on wire dissolves readily to a yellowish-green glass, losing much of its color on cooling, and becoming dark-green in E. P. "With soda on coal affords lead. When fused with bisulphate of potassa in the platinum spoon it forms a yellowish mass, becoming white on cooling, and this dis- solved by treating it in distiUed water, a£fords a solution which very quickly becomes dark-blue on adding a bit of zinc or tin. The varieties from Phoenixville and Ruksberg give a mass which is colored very pale yellowish-green (chromium). Stolzite decrepitates in the matrass. On coal fuses, with forma- tion of a lead coat, to a globule that crystallizes in cooling and has a dark metallic surface, 'while it shows a grayish-white, vitreous fracture. Dissolves easily in tho glass fluxes in 0. F. to a clear col- orless bead. (The borax bead in R. F. becomes yellowish, and some- times on cooling is gray and opaque.) The S. Ph. bead in R. F. after short treatment assumes a blue color, but sometimes not so pure aa from tungstic acid alone. Too large a quantity, or too long blowing, renders the glass greenish and finally quite opaque. Reduced with soda yields lead. When fused like the preceding mineral with bi- sulphate of potassa and dissolved, the solution gradually becomes grayish-blue on adding zinc or tin. To detect tungstic acid readily in the wet way, see the examination for tungstic acid. Bindheimite yields water and becomes darker in the matrass. On coal is reduced to a metallic button, which volatilizes gradually, coating the coal with oxides of lead and antimony. c Examination for lead in metallurgical products, together with their blowpipe characteristics. The various samples of commercial lead sometimes contain more or less copper, antimony, and arsenic. If such lead is fused and kept in rotary motion, B. B. on coal, arsenic can be detected by the odor, and antimony by the coat deposited beside the lead coat. A very trifling amount of antimony can be found by using boracic acid, vide antimony. 232 plattnek's blowpipe analysis. To detect any copper present, a bit of the lead is treated with vitrified boracic acid on coal, until nearly all of the lead is slagged off, when the remaining metal button is fused with S. Ph. in 0. F., vide copper. SilTer is found by cupelling the lead, vide silver assay. Plumbif- erous Hack copper varies in character, but always yields a distinct lead coat. Other ingredients are found according to the directions under the general examination for iron in alloys, p. 183. The behavior of speisses and matts is also given under iron. Litharge behaves B. B. like oxide of lead. If containing arsenate or antimonate of lead it affords, on reduction, an arsenic odor, or an antimony coat. Copper is found by reducing some litharge to metallic lead and treating the button with boracic acid and after- ward with S. Ph., using tin if necessary, vide copper. Aistrich from the cupellation for silver when treated alone on coal is reduced to metallic lead, emits a strong arsenic odor and yields coats of lead and antimony. Copper is found as in litharge. To detect iron a larger piece of abstrich is reduced beside a small borax bead on coal, keeping the glass constantly covered with a good R. P., and shaking off the reduced lead upon the anvil from time to time. By remelting this glass on platinum wire in 0. P. the iron can be raised to the state of sesquioxide and recognized. To detect sulphuric acid, not too small a quantity of the abstrich is powdered and reduced with soda on coal, the resulting fused mass cut out from the coal and laid on moistened silver foil, vide sul- phuric acid. Alzug behaves in general quite like abstrich, but if much of the hearth mass is mixed with it the metallic oxides can only be reduced by adding borax, or soda and borax. Cupel bottoms or hearths, from the cupellation for silver, as well as the flue rakings and lead smoke from lead smelting, cupelling and roasting processes, at once yield a lead coat when treated alone on coal in R F. The manner of detecting the other ingredients may be inferred from what has preceded. Slags containing oxide of lead yield a lead coat either alone on coal in E. P., or when fused to a globule with soda. The othei ingredients are found by the method given under lime. TIN. 233 9. TiK, SiL Its occurrence in the mineral kingdom and in metallurgicdl products. Tin occurs, in nature, in the following minerals : — a. Combined with sulphur in Stannite (tin pyrites) —Ou" S + E S + Sn S', E = Cu, Fe and Zn, with 24.1 to 31.6 Sn and 29 Cu; Franokeite,— (3 Pb 8 + Sb' S=) + 2 (Pb S + Sn S'), with 13.5 Sn and some Ag and Ge. Cylindrite,— (3 Pb 8 + 8b» 8=) + 3 (Pb 8 + 3 Sn S^), witli 17 Sn. b. As oxide in Cassiterite (tin-stone), — Sn 0°, with 78.6 Sn, but generally contain- ing trifling quantities of Fe' 0', Mn" 0', and occasionally some Ta' 0' or Nb' 0'- Stannit from Cornwall,— Si 0', Sn 0' and a little Al" 0' and Fe" 0' with 30.5 Sn. Tin is likewise found as an unessential ingredient in several other minerals, viz., meteoric iron, titanic iron, tantalite, columbite, fergusonite, monazite, thorite, olivine, euclase, and cerstedite. This metal is rarely to be sought for among metallurgical products except in the especial products of the tin works, including : — a. The varieties of tin in commerce, most of which not un fre- quently contain more or less Fe, Cu, and As, and occasionally W, Mo, and Bi ; i. The scraps obtained in smelting tin ores and refining tin, usually containing a notable amount of Fe and As, also occasionally showiug Cu, Bi, W, and Mo; c. Deposits which form on the soles of the shaft furnaces when smelting tin ores, and consist chiefly of Fe and Sn, but not unfre- quently contain some As, Cu, W, Mo, and Bi ; d. Tin slags. EKamination for Tin. Including the blowpipe characteristics of the minerals mentioned above. a. General examination for tin. The behavior of metallic tin and the coat of oxide on charcoal have been given on p. 68. If the tin contains lead or bismuth it 234 plattkek's blowpipe analysis. is scarcely possible to keep a globule of the alloy in fusion, even in the best R F., without having it covered with a crust of oxide. By adding borax, however, and treating this with the E. P., an admix- ture of lead or bismuth may be recognized by the yellow coat de- posited on the coaL Should it be doubtful whether lead or bismuth is present, the coat is carefully scraped off, dissolved in S. Ph. on platinum wire, and the bead treated on coal with tin. Bismuth ia indicated by the gray or black appearance of the cold bead. It is easy to confound the S. Ph, reaction with that of antimony, and another method, more certain, is given under bismuth. The presence of arsenic is ascertained by the odor, while treating the alloy with the borax, which afterwards oxidized on platinum wire will also show a yellow color in presence of iron. Tin is tested for copper by fusing it on coal with a mixture of one hundred parts by weight of soda, fifty borax, and thirty silica, as described in the separation of tin from copper under the quantitative copper assay. The remaining button of copper, containing only a little tin, is treated with S. Ph. on coal in 0. P., until the glass is colored. The S. Ph. glass may then be further tested with tin, to ascertain whether copper is actually present or not. Tungsten, which usually is present only in trifling quantities, cannot always be detected with certainty by the fluxes, because the tin is seldom quite free from iron ; but on dissolving enough of the tin by warming it with aqua regia, diluting with water, decanting the clear solution after the residue has settled, and digesting the latter with fresh aqua regia» yellowish-green tungstic acid remains, if the tin contained tungsten. The acid solution, usually yellow from iron, is again decanted, the residue of tungstic acid washed with water, and tested with S. Ph. on platinum wire, when after a short treatment in K. P. it affords a blue bead. Tin, when present in alloys, is almost always detected on fusing them upon coal, since the globule cannot be kept bright even in the E. P., but quickly becomes covered with an increasing crust of oxide, which can only be removed with difBculty after adding borax. Metallic sulphides containing tin, but yielding no coat of oxide of tin near the assay when treated alone on coal, must be roasted and treated in E. F. with soda and borax, when metallic tin is obtained, which may be tested alone on coal. If other redu- cible metals are present they afford an alloy, in which the othei metals can be recognized by means of the fluxes. In metallic oxides, or substances generally, which are composed of oxides, tin may be best detected by a re- EXAMIN-ATIOIT FOR TIK. 335 duction assay on coal with soda, or neutral oxalate of potasea ; it m, however, necessary in certain cases, to add borax, so as to slag off the considerable amount of iron present. i. Blowpipe characteristics of the above minerals. Stannite alone on coal in R. F. fuses tb a globule. In 0. F. it eyolves sulphurous acid and is covered with oxide, which is also deposited on the coal near the assay and can be immediately recog- nized by its well-known properties, p, 68. In the open tube it yields sulphurous acid and some oxide, which collects quite near the assay and cannot be volatilized again. Well roasted with alternate 0. F. and R. F., it shows iron and copper with borax. A little zinc, which may be found in the wet way, cannot be detect- ed B. B., since the coat which it forms is concealed by the oxide of tin. Cassiterite is unaltered in the matrass. In the forceps is infus- ible. On coal some specimens, especially in E. F., give a white coat of binoxide of tin and metallic tin ; others are not altered and only yield tin globules on fusion with soda or oxalate of potassa. With borax sometimes gives a feeble iron color; with soda and nitre often a feeble manganese reaction, A small quantity of tan- talic or niobic acid can be found by the method to be given under tantalum and niobium. Gylindrite yields sulphur in the matrass, and near the assay a slight reddish sublimate (antimony oxysulphide). In the open tube yields sulphurous and anti- monouB acids and a sublimate which settles at the bottom of the tube near the assay, is yellowish-white and for the most part not volatile. On coal it fuses and gives a yellowish-white coat near the assay and a white coat of oxide of antimony farther away. The yellowish-white coat is a mixture of Pb O, Sb' O', Sn 0=, and Sb^ 0''; with cobalt solution it becomes bluish-green. With soda on coal yields an alloy (Sn, Pb and Sb), which in O. P. does not fuse with a bright surface, but is quiclily covered with an infusible layer, rapidly in- creasing in volume (Sn 0'). Franckeite, containing a little Ge, behaves similarly. Stannit is infusible on coal and in the forceps. It dissolves slowly to a colorless glass in borax and S. Ph. giving a silica skele- ton with the latter. With little soda fuses to a slag-like mass, with more in E. F. affords metallic tin. e. Examination for tin in metallurgical products, including their llowpipe characteristics. The behavior of commercial tin may be deduced from the remarks under a, on tin in general. 236 plattitee's blowpipe analysis. The different sorts of tin scraps from smelting and refining tin behave variously, but their constituents may be quickly detected by testing tliem on coal and with the fluxes, observing all that was said under a. The deposits on the sole of the furnace, treated on coal with borax in K, F., sometimes yield an unmistakable coat of oxide of tin. The manner of detecting the remaining ingredients may be deduced from the general remarks on metallic compounds under iron, p. 183. Should there be so little tin, however, as to yield no distinct coat, it is only necessary to dissolve the product in nitric acid and test the residue of binoxide of tin with soda on coal. Tin slags fuse in E. F. alone on coal, without producing a notice- able coat, but by a reduction assay with soda and borax, metallic tin is obtained. The other ingredients are detected as given under lime, p. 128, but some silver must be added when it is proposed to reduce all the oxide of tin. If the slag cc atains tungstic acid the whole of the tungsten is found in the separated silica, vide tin slags, under tungsten. 10. Bismuth, Bi Its occurrence in the mineral kingdom and in metallurgicaJ products. Bismuth belongs to the rarer metals ; it is found: a. Metallic in Native bismuth, — Bi. Chilenite, vide silver; maldonite, vide gold. i. Combined with tellurium and selenium in Tetradymite. 1. Free from sulphur {Tellurwismuth), — Bi' Te', with 52 Bi. 2. Sulphurous. Bi" Te' S, with 59 Bi. Guanajuatite (frenzelite), — Bi" Se', with 67.3 Bi; a part of the Se probably replaced by S. Joseite,— 2 Bi" Te' + Bi" S", with 79.1 Bi; -^ of the Te is replaced by Se. c. With sulphur in Bismuthinite {bismuth glance), — Bi" S', with 81.2 Bi, occasionally some Fe and Cu; Emplectite,— Ou' 8 + BP 8«, with 62 Bi and 18.9 Cu ; Wittiohenite,— 3 Cu" 8 + Bi» 8', with 42 Bi and 38.4 Cu ; Klaprothollte,— 3 CuJ 8 + 2 Bi" 8», with 55.4 Bi, but mostly mixed with some ohal- oopyrite and native Bi ; BISMUTH. 237 Matildite,— Agi! S + Bi" S', with 54.7 Bl and 28.3 Ag ; Sohirmerite,— 2 Ag' S + Pb 8 + 2 Bi^ S=, with 47.3 Bi ; Galenobismutite,— Pb S + Bi» S', with 55.6 Bi and 27.4 Pb j Ailcinite, chiviatite, Icobellite, oosalite, vide lead ; Annivite, tetrahedrite, vide copper. d. As sulphide combined with oxide in Kareliuite,— 3 Bl 0, Bl S, with 91.2 Bi. e. As oxide in Bismite (bismuth ochre), — Bi" 0', with 89.6 Bi, but always contain- ing a little Fe" 0', 0", H' 0, and occasionally As" 0'- /. Combined with arsenic acid in Ehagite,— 3 Bi" 0', As" 0', 2 H" 0, with 82.1 Bi, but containing a little Co, Fe, Al, and Ca; Ateleshte is similar. "Walpurgite,— 5 Bi" 0\ 3 (U 0") 0, 2 As" 0' + 12 H" 0, with 60 Bi. ff. Combined with carbonic acid in Bismutosphserite,— Bi" 0", C 0", with 81.8 Bi; Bismutite ( Wismuthspath), basic carbonate of bismuth, of varying composition, with 86.9-95.9 Bi. h. Combined with telluric acid in Montanite,— Bi!" 0», Te O' + 1 or 2 H» O, and with a Uttle Fe' 0», Pb O, Cu 0. i. With vanadic acid in Pucherite,— Bi' 0', V" 0°, with 71.7 Bi; contains some As" 0' and P"0'. k. With silicic acid in Eulyti*e, 1 A, 1 G; chiefly 2 Bi" 0', 3 Si 0", with 83.75 Bi, and also some ferric phosphate ; agricolite is similar. Blsmutoterrlte, from Sohueeberg,— Bi« 0', 2 Fe" 0', 4 Si O". Hypochlorite, from the same place, is a mixture of Si 0", Fe» 0% and Bl' 0' (4.7 per cent.). Bismuth is also found in certain metallurgical products, viz. : in various speisses and matts from smelting cobalt and nickel ores containing bismuth; also in Blicksilber (from cupellation) and in some tin. 238 PLATTNEES BLOWPIPE ANALYSIS. Examination for Bismuth. Including the blotopipe characteristics of the above-named minerals. a. General examination for bismuth. Bismuth in alloys, as they occur in nature and among metallur- gical products, may be recognized by the coat afforded by the sub- stance alone on coal, and which is best obtained in R F. It is dark orange-yellow while hot, lemon-yellow on cooling, and changes its place under the E. F., without coloring the flame, p. 68. When easily volatilizable metals are present they partly pass off, partly in fumes and partly afford a coat, adjoining the bismuth coat, e. g., tellurium, arsenic, etc. Bismuthiferous lead is treated alone on coal, until a distinct coat is produced, which is carefully scraped off, dissolved in S. Ph. on platinum wire in 0. F., and the colorless bead treated with tin on coal in E. F. If bismuth was present the cold bead is dark-gray or nearly black. Acids of antimony, howeyer, produce a similar reaction, and the metallic compound must first be freed from antimony, if present, by treating it for some time on coal in 0. F., and then keeping it melted on a fresh coal, until a coat is formed, which will suflace for the S. Ph. test. To very infusible alloys, containing nickel, for Instance, some pure Bilver must be added, and the whole treated in E. F. When the bismuth is combined with sulphur a white coat of sulphate of bismuth forms beyond the yellow coai^ but this ** **' may be prevented by adding soda. The presence of much lead causes a mixed coat of oxides of lead and bismuth, which can hardly be distinguished from a pure lead coat, and a trifling amount of bismuth can then only be detected by a special test, as above, with S. Ph. Any antimony sulphide pres- ent must first be completely removed by fusing the assay on an- other part of the coal, as before described, before forming the bis- muth and lead coat. When substances containing oxide of bismuth are treated alone, or with soda, on coal, they yield an unmis- takable bismuth coat. Should there be any doubt, the coat may be scraped off and tested with S. Ph., provided the substances are free from oxide of antimony. Merz (Journ. f. prakt. Chem., vol. 101, p. 269) recommended the change of the oxide coats into iodides to distinguish between lead EXAMTNATIOX FOR BISMUTH. 239 and bismuth oxides, which had already been used in another way for this purpose by Bunsen in his flame reactions. The lead iodide coat is lemon-yellow when heavy, and almost greenish when thin; the bismuth iodide coat is intense scarlet-red. According to v. Kobell {Journ. f. prakt. Chem. JV. F. vol. 3, p. 469) this very characteristic and suitable test for bismuth is most surely made by fusing the compound, even when already con- taining sulphur, with sulphur on coal and then strewing the assay, with enough powdered potassium iodide to cover it on melting. After a short blast a white to yellowish coat appears nearest the assay, fringed by the brilliant red coat, whose color gradually bleaches, so that after a time the coat appears lighter. It is well to keep on hand a mixture ol equal volumes ol powdered potassium iodide and sulphur which can be fused with the powdered assay. (Moses and Parsons recommend a mixture of 1 part of potassium iodide, 2 of sulphur and 1 of potassium bisulphate.) A few other volatile metals, Hg| Sb, Cd, Sn, Tl, also give in this way peculiar coats, but these can hardly be mistaken for the bismuth coat. According to Cornwall's experiments {B. u. h. Zeit., 1872, p. 438) this reaction for bismuth fails or becomes indistinct in case of lead oxide with a trifling amount of bismuth. He then recommends that the test be made in an open glass tube about 10 centim. long and at least 8-10 millim. in diameter over an alcohol lamp or Bunsen burner, using a mixture of 5 parts of sulphur with 1 of potassium iodide, in quantity equal to that of the assay substance. On the edge of the yellow sublimate, which also forms, there will be obtained a ring of the bismuth iodide, distinctly red, or with very small quantities of bismuth, orange-red. Farther from the assay there may be formed a sublimate of iodine, not to be con- founded with the bismuth sublimate. In presence of much oxide of antimony the white antimony coat completely hides the bismuth reac,tion.. Cornwall then recom- mends that the oxides be fused with an equal volume of sulphur in a shallow cavity on coal, treating them alternately with 0. P. and K. F. until the antimony fumes nearly cease. The powdered residue is then treated in the open tube as above; and the same test can be applied to native sulphides after volatilizing the excess of antimony on coal. 240 plattner's blowpipe AJS'ALYSIS. b. Blowpipe characteristics of the minerals containing bismuth above mentioned. Native bismuth behaves like pure bismutli, p. 68. COMPOUKDS OP BISMUTH WITH TELLUEIUM, SULPHUE, AXD SELENIUM, SEPAEATELT ASTD TOGETHEE. Tetradymite, free from sulphur, fuses easily and yields in the open tube white fumes, which partly stream through the tube and partly condense near the assay; when selenium is present a strong heat causes a red spot due to the admixture of selenium, which also imparts a strong odor of selenium to the escaping gas. The white coat fuses B. B. to clear, colorless drops, and is thus recognized as itellurous acid, but the reddish film volatilizes. After the volatile constituents are mostly expelled the metallic globule is surrounded by brown fused oxide of bismuth, which is opaque and yellow when cold. On coal fuses very easily to a metallic globule, colors the Jame bluish-green, diffuses, if seleniferous, a distinct selenium odor, -and deposits a white coat, with a dark orange-yellow one still nearer the assay. The former disappears under the E. P. with a bluish- green flame, the latter becomes lemon-yeUow on cooling. The remaining button can be entirely volatilized, furnishing an abundant bismutli coat. To test with potassium iodide and sulphur, selenium is first re- moved B. B. on coal, and the residue is then tested as described. The sulphurous varieties also yield sulphurous acid in the tube. Guanajuatiie in the closed tube yields a yellowish-red sublimate (S and Se), in the open tube, S 0' and Se. Fuses easily on coal, gives the selenium odor and an azure-blue flame. The coat is first gray, then white (bismuth, sulphate and selenite), with a reddish «dge; B. B. this disappears, coloring the flame blue; the coal near the assay has a coat of bismuth oxide. The small amount of slag near the button reacts for iron, perhaps due to admixture of pyrite. Joseite. — Its behavior follows from what has been above stated. BISMUTH COMBIlfED WITH SULPHUE AKD OTHEB METALLIC SULPHIDES. Bismuthinite fuses in the closed tube, yielding a little sulphur. Carefully heated in the open tube it fuses, yielding sulphurous acid EXAMINATION rOR BISMUTH. 241 and a coat of sulphate of bismutli, which fuses B. B. to brown drops, yellowish and opaque on cooling. Strongly heated the assay boils, and oxide of bismuth is deposited in the surrounding glass. On coal it first yields some sulphur, then fuses, spirts out glowing drops, and deposits coats of oxide and sulphate of bismuth. When all the bismuth is removed a trifling scoria usually remains, which fre- quently %ffords iron reactions and sometimes copper with the lluxes. Emplectite and wittichenite behave similarly. The residue ou coal yields a copper button with soda or neutral oxalate of potassa. Klaprotholite behaves similarly. Matildite fuses easily, B. B. evolves S 0', gives on coal a yellow- ish-white coat and finally leaves a somewhat malleable silver button. SULPHIDE WITH OXIDE OF BISMUTH. Karelinite yields some s.ulphurous acid, but no sulphur, in the matrass; metallic globules of bismuth separate from the fused mass. In the open tube sulphurous acid and a button of metal, surrounded by easily fusible oxide of bismuth. Hermann. OXIDE OF BISMUTH. Bistnite generally yields water, and upon addition of hydrochlorio acid frequently shows a little carbonic acid. With fluxes and on coal, like oxide of bismuth. SALTS OF BISMUTH. Rhagite decrepitates in the matrass, yields water and forms an isabel-yellow powder. On coal fuses, yielding an arsenic odor and a bismuth coat and button. Walpurgite decrepitates in the matrass, grows darker and gives little water. In the forceps colors the flame pale blue and melts very easily. With borax and S. Ph. gives uranium reactions, and the S. Ph. bead with tin shows bismuth. On coal, a bismuth coat and arsenic odor. Bismutite in the matrass decrepitates, yields water, becomes brown, and fuses readily on the glass. On coal is quic'kly reduced to bismuth. In S. Ph., a dark yellow bead, colorless on cooling and showing flakes of silica. Dissolves in nitric acid with effervescence, leaving a yellow, clayey residue. (Rammelsberg.) Montanite yields water in the closed tube. B. B. gives reactions 343 plattner's blowpipe analysis. for bismuth and tellurium. With hydrochloric acid yields chlorine and dissolves. Pucherite decrepitates violently in the matrass, fuses B. B. on coal, gives a bismuth coat and a slaggy mass. With soda, metallic bismuth. With boraz and S. Ph., vanadium reactions. The S. Ph. bead on coal with tin becomes black. Eulytite is unaltered in the closed tube. (According to Dana decrepitates and affords a trace of water.) In the forceps fuses very readily with intumescence, and if pure, tinges the flame bluish- green (phosphoric acid). On coal swells and fuses easily to a brown bead, deposits a bismuth coat and sometimes emits an arsenical odor. With soda yields metallic bismuth. The S. Ph. glass shows silica, is yellowish while hot, colorless on cooling, and with tin on coal shows bismuth. Hypochlorite is infusible in the forceps, but assumes a dark-brown color. With sulphuric acid the powder yields a distinct phosphoric acid flame, p. 76. On coal in E. F. yields a trifling bismuth coat, without fusing. Dissolves slowly in borax, showing iron, and the saturated glass in K. P. on coal becomes somewhat cloudy and then assumes a yellowish-green color, while a slight bismuth coat is formed. The S. Ph. bead is yellow and shows silica ; on coal with tin becomes dark gray. With soda on coal it fuses with effervescence to a globule, and produces a distinct bismuth coat, while a slight manganese reaction is obtained with soda and nitre. c. Metallurgical products. ■ The remarks under the general examination for bismuth applj here. 11, Ueakium, TJ. Its occurrence in the mineral kingdom. Uranium is found in the following minerals : a. As oxide in tlrauiuite {pitchllende), — probably U' 0'. Massive varieties are geueiiiljy impure, from sulphides, arsenides, carbonates, etc., and so contain Pb, Bi, Cu, Zn, Fe, Mn, Ca, Mg, As, Si, and S. In the crystalline varieties always occurs Pb 0, Th 0'. Eliasite and gummite are hydrated uranium oxides with the same impurities as urauiuite. EXAMINATION FOR UKANIUM. 243 b. With acids; a. AVith sulphuric acid in Zippeite, uraoonite, Vranviiriol, johannite, uranochaloite, which contain also some Fe and Ca, and in part Cu (johannite, uranochaloite). yS. With arsenic acid in Trogerite — 8 (U 0') 0, 3 As' 0' + 31 H' ; Zemierite,— Cu 0, 2 (U 0') 0, As'' 0' + 10 H' 0; Uranospinite,— Ca 0, 3 (U 0") 0, As'' 0=+ 10 H' 0; Walpurgite, — vide bismuth. y. With phosphoric acid in Autunite {lime-uranite), —Ca, 0, 2 (U 0') 0, P' 0' + 8 H' 0, and a little Ba ; Torbernite {copper uraniie),—Gn 0, 2 (U 0') 0, P' 0' + 8 H' 0. The Tai-iety from Cornwall contains some As' 0*; Uranocircite,— Ba 0, 3 (U 0") + 8 H" 0; Phosphuranylite,— 3 (U 0") O, P" 0= + 5 H» O. S. With carbonic acid in Uran-Kalkcarbonat from Joaohimsthal ;— 2 U C" 0» -f 2 Ca C 0' 4 9 H" O ; Uranothallite and liebigite are of similar composition ; also vogUte (containing Cu). e. With silicic acid in Uranophane and uranotil, hydrous silicates of uranium with 53.3 to 66.8 per cent. U 0', and AV 0', Ca O, Mg 0. Uranium also occurs in larger or smaller quantity in : JPyrochlore, fergusonite, yttrotantalite, euxenite, polycrase, samarskite, and thorite vide lime and yttria. Examination for Uranium, Including the blowpipe characteristics of the minerals above enumerated. a. General examination for uranium. When testing for uranium the chief point to be considered is the behavior of its oxide with S. Ph., with which in 0. F. it yields a yellow glass, becoming yellowish-green on cooling and pure green in E, F., p. 85. In absence of other oxides producing similar colors, S. Ph. yields decisive results, but when oxides of iron and possibly also titanic acid are present, in which case the S. Ph. bead in K. F. becomes red on cooling, vide iron, p. 186, the uranium color can only be perceived by treating the glass in 0. F., when it assumes on cooling a green color, mixed with much yellow. When there is little uranium "and much iron the fluxes show 244 plattnee's blowpipe astaltsis. 5>nly the iron, and the substance must then be treated with bisul- phate of potassa, carbonate of ammonia, etc., vide iron, p. 186. Substances containing oxides of copper and uranium yield green beads in 0. F. with borax and S. Ph., and as substances containing oxides of iron and copper, without uranium, do the same, the fol- lowing method may be adopted to detect the presence of a little nrauiura. The substance is treated with soda, borax, and a silver button on coal in R. F., until all the copper is reduced into the silver, after which the slag, containing uranium and other non- reducible oxides like oxide of iron, in a low state of oxidation, is dissolved by warming it with a little aqua regia, treated with excess of carbonate of ammonia and the process conducted according to p. 186. b. Bloiopipe characteristics of the above-mentioned uranium minerals. Uraninite from Johann-Georgenstadt yields some water at first, then usually, if containing many foreign substances, a trifling subli- mate of sulphur, next sulphide of arsenic, and finally metallic arsenic. In the open tube evolves sulphurous acid, and a ring of arsenous acid collects on the tube; the assay does not alter perceptibly. B. B. is only rounded somewhat on the edges and usually tinges the flame azure-blue (lead), near the assay, and fine green at a greater distance (copper). The thoroughly ignited mineral behaves with the glass fluxes like oxide of uranium, p. 85. It is not dissolved by soda, but if treated in R. F. on coal, which often causes a perceptible odor of arsenic, after washing away the coaly particles and any oxide of uranium in the mortar, it yields metallic particles of a light copper color, apparently consisting of plumbiferous copper, since a yellow coat is also produced on the coal. A test with S. Ph. establishes this supposition. Gummite and eliasite yield much water; but otherwise like uraninite. The sulphates of uranium yield water in the matrass, and change color; on coal evolve sulphurous acid, and react for uranium with the fluxes. The S. Ph. bead with tin on coal is dark-red in presence of copper. The nitric acid solution treated with water and ammonia in excess yields a yellow precipitate, which behaves like oxide of uranium with the fluxes. If Cu O is present the ammoniacal solu- tion is blue. EXAMINATION FOR URANIUM. 245 With soda on coal they all yield a strong sulphur reaction. Trbgerite gives considerable water in the closed tube and grows darker. In the forceps fuses easily ; gives a pale-blue flame. On coal, a distinct arsenic odor, and with soda a brownish-black slaggy mass. The glass fluxes show uranium. Axttunite yields water and becomes opaque straw-yellow in the matrass. On coal fuses with some intumescence to a black globule, with a crystalline surface. With the glass fluxes shows uranium. With soda a yellow, unfused slag. (Berzelius.) Torhernite behaves like autunite, but shows copper with S. Ph. and tin, as well as on reduction with soda. The copper button is frequently whitened by arsenic, which can be recognized B. B. by its odor. LieMgite yields water and becomes greenish-gray in the matrass. At a red-heat blackens, without fusing, but becomes orange-red on cooling. Voglite colors the flame green; with soda gives metallic copper. B. B. in forceps and on coal is infusible but remains black. With borax in 0. F. a yellow bead, green in E. P. Dissolves with lively effervescence in hydrochloric acid, forming a yellow solution. (J. L. Smith.) The related Z7raM-.fia?^cfl!J'5o«a< loses water and becomes grayish- black, or by access of air brownish-black, is infusible, and shows wranium with fluxes. UranopJiane yields alkaline water in the matrass, blackens, and on cooling is rusty brown. In the open tube becomes almost orange-yellow, and strongly heated yields trifling vapors and a coat, partly volatile and partly fusible to drops, Te 0^, and a feeble selenium odor is perceptible. Alone the mineral fuses to a black glass and imparts a slight copper coloration to the flame. On coal affords coats of Sb and Bi. With the fluxes shows Si 0' and uranium. 246 plattner's blowpipe analysis. 13. Copper, Cu. Its occurrence in the mineral kingdom and in metallurgical products. Copper occurs quite extensively in nature, being found: a. Metallic in Native copper, Cu, occasionally argentiferous. b. Combined with arsenic in Whitneyite,— Cu" As, with 88.3 Cu, ) . , , . . Algodonite,-Cu'As, with 83.5 Cu! [ "'^''^^ always containing Domeykite,— Cu' As with 71.6 Cu, ) ^°™^ ^' Condurrite is a mixture containing Cti, As, S, and probably results from the decomposition of Tennantite. c. Combined with selenium in Crookesite,— (Cu, Tl, Ag)' Se; but the silver is said to come from admixture of eucairite. Berzelianite, — Cu' Se, with 61.6 Cu; Umangite,— 2 Cu' S + Cu Se; Eucairite, vide silver ; Zorgite and SelenquecTcsilherkupferhlei, vide lead; d. Combined with sulphur in Chalcocite (copper qlance), — -Cu' S, with ) ... ■ ,, p, p ^ f containing occasionally Digenite,-Cu' S + Cu S, with 70.4 Cu, ) ^^' ^^' ''''^ ^^ ' Covellite (indigo-copper), — Cu S with 66,4 Cu, but not always free from Fe and Pb; cantonite has the same composition; Bornite {purple copper), — a;Cu' S +yCu S + zPe S, with 43 to 63.4 Cu; barnhardtite, with 48.3 Cu, and homichlin, with 44,3 Cu, are varieties of bornite ; Chalcopyrite {copper pyrites), As' S'+ Fe' S', with 34.4 Cu ; Tennantite {Fahlerz in part),— 4 (Cu', Fe) S + As' S', with 47.7 to 51.6 Cu; julianite is similar; Kupferblende, from Freiberg,— 4 (Cu', Zn, Fe) S + As' S', with 41 Cu and traces of Pb, Sb, and Ag; Enargite,— 4 Cu S + Cu' S + As' S', with 48.3 Cu, and a little Fe and Zn; some As also replaced by Sb; luzonite has the same composition ; Famatinite,— 4 Cu S + Cu' S + Sb' S', with 43.2 Cu, and a little Fe and Zn ; a small part of Sb replaced by As ; COPPER. 247 Tetrahedrite {Falderz, gray copper), eiihQv — 4 (Cu", Ag^Fe, Zn, Hg) S + (Sb, As)' S', or— 3 (Cu^ Ag', Fe, Zn, Hg) S + (Sb, As)' S=. Divided into antimonial, arsenical, and antimonial-arsenical Fahlerz. The antimonial F. richest in silver; the arsenical P. frequently free from silver; while the proportion of copper is reversely present. Cu, 15-43; Ag, 0-31; Hg, 0.5-17.3. Pb, Bi, Co, and Ni scarcely ever present; Epigenite,— 9 R S + As' S^ R = Cu (40.6) and Fe ; Binnite,— 3 Cu' S + 2 As" S% with 39.2 Cu ; Lautite, — Cu (Ag) As S ; Klaprotholite (vide bismuth), with 25.4 Cu ; Annivite,— 3 Cu» S + As' S=, and some Fe S, Zn S, Sb' S', Bi' S' ; Stylotypite,— 2 (Cu, Ag)' S + Fe S + Sb' B' ; Wittichenite, vide bismuth ; Stromeyerite, jalpaite, lichtes Weissgiltigerz, vide silver ; Stanuite, vide tin. Chalcostibite,— Cu» S -|- Sb' S', with 25.6 Cu, but containing a little .Feand Pb; Cubanite,— 3 Fe S + Cu S, with 22.9 Cu and traces of Pb ; Bournonite, aikinite, alisonite, cuproplumbite, olayite, vide lead ; Polybasite, vide silver. e. Combined vpith chlorine in Nantokite,— Cu= CP, with 64 Cu; Atacamite, — Cu Cr, 3 Cu 0, 3 H' 0, but compounds occur with moreH'O; Cu = 52.7-59.4; Percylite, vide lead. /. As oxide in Cuprite {red copper, chalcotriclnte), — Cu' 0; Cu = 88.7; Melaeonite {tenorite),^Cxi 0, with 79.8 Cu; on crevices in Vesuvian_iava; also mas- sive at Lake Superior, with at times some Fe' 0', Ca O, Si O', as impurities; Kupferschwdrze from Lauterberg, a mixture of various oxides and containing Cu ; Crednerite, lampadite, vide manganese. ff. Combined with flci^.s.- a. With sulphuric acid in Brochantite,— 4 Cu 0, S 0» -1- 3 H' 0, with 56.1 Cu; Langite,— 4 Cu 0, S 0' -f- 3 H' 0; Cyanotrichite {lettsomite),—^ Cu 0, AF 0', S 0' -|- 8 H' 0, with 38.3 Cu; woodwardite is similar; Chalcanthite [copper vitriol),— Cn S 0* + 5 H' 0, with 25.4 Cu; Cyanochroite,— K' 8 0< + Cu S 0< + 6 H' ; Pisanite, — vide Iron. yS. 'With. }ihosphoric acid m Pseudomalachite,— 6 Cu 0, F 0^ + 3 H' 0, with 56.6 Cu; in the variety from Ehl some P' 0' replaced by As' 0"; 248 plattner's blowpipe analys-is. Dihydrite,— 5 Cu 0, P» 0' + 3 H= O, with 55 Cu ; Ehlite,— 5 Cu O, P= O' + 3 H" 0, with 53.3 Cu; according to Bergemann the Ehl vari- ety contains V^ 0* ; Libethenite,— 4 Cu 8, P^ 0= + H' 0; Cu = 53.3; according to Bergemann contains 2.S per cent. As^ 0^ ; Tagilite,— 4 Cu 0, P^ 0« + 3H» O ; Cu = 49.4 ; Thrombolite,— 3Cu 0, Ps 0» + 6 H" ; Cu = 30; Torbernite, vide uranium. /. With carbonic acid in Malachite,— 2 Cu 0, C 0=^ -\- B.' 0, with 57.4 Cu; Aznrite,— 3 Cu 0, 3 C 0" + H= 0, with 55.2 Cu; Aurichaloite, buratite, vide zinc ; Caledonite, vide lead. 6. With arsenic acid in Cllnoclasite,— 6 Cu 0, As" 0' + 3 IP 0, with 50 Cu; Olivenite,— 4 Cu 0, As" 0' + IP 0, with 45.2 Cu; a little of the As' 0' replaced by P" 0'; Cornwallite,— 5 Cu 0, As" 0» + 5 or 3 H'' 0; Erinite— 5 Cu 0, As" 0^ + 2 H" ; Euohroite,— 4 Cu 0, As" 0» + 7 H» 0, with 37.5 Cu ; Tyrolite and trichaicite are similar basic copper arsenates ; Chaloophyllite,— hydrous copper arsenate with Al" 0=, and frequently some P" 0= ; Lirooonite is similar in composition; Coniohalcite, — isomorphous mixture of basic arsenates, phosphates and vanadates of copper and lime; Zeunerite, vide uranium. e. With chromic acid in Vauquelinite, vide lead. C. With vanadic acid in Volborthite,— 4 E 0, V 0' + H' ; E chiefly Cu and Ca. Volbor- thjte from the Ural seems to be the pure copper compound. 77. With tungstic acid in Cuprotungstite,— 2 Cu 0, W 0' + H" ; and a little Ca O and Fe" 0". 18. With selenous acid in Chaloomenite,— Cu Se 0= +• 2 H" 0. I. With silicic acid in Dioptase, III, I G,— Cu 0, Si 0" + H' 0, with 39.9 Cu and a little FeO; Chrysocolla, III, 1. Hydrous silicate of copper of varying compo- sition. Cu 0, Si 0' + 1 or 2 W 0. Kupferpeckerz, so-oalled, is chiefly a mixture of limonite and copper silicate; Allophane, vide alumina. EXAMINATIOK FOE COPPER, 249- Copper is also frequently found, in addition to the regular copper products, as an accessory ingredient of the silver and lead products of smelting works, when the ores treated were cupriferous. It there- fore occurs : a. Metallic as Refined copper, cement copper, and in combination with other metala as raw or llaclc copper ; in liquation discs, and residues ; in cu- priferous bears, which form under certain circumstances on the sole of the shaft furnaces when copper ores or products rich in iron are smelted ; finally in cupriferous raw lead. As already remarked under iron, p. 182, Pb, Ni, Co, Fe, Zn, Mo, Sbi and. As, may occur with the copper, and occasionally some Ag. b. Combined with sulphur in the various matts and speisses, vid& iron, p. 183 et seq. c. As oxide in The scoria from copper refining; in abstrich and litharge from cupelling lead, as well as with silicic acid in the slags of silver, lead and copper smelting. Ezamination for Copper, Including the blowpipe characteristics of the foregoing minerals. a. General examination for copper. Most native combinations of copper with other metals contain selenium ; when this is expelled in 0. P. on coal, other easily- *'^'" volatilized metals being also partially removed, and the re-, maining button is treated with borax in 0. P., the resulting glass is, colored usually with oxide of copper, p. 83. This cold glass treated in R F. on a fresh coal, becomes red and quite opaque on cooling, but sometimes, if the E. F. is kept up too long, the copper is reduced. and leaves the glass colorless. The reaction succeeds better when the glass is treated a few seconds beside some tin in E. F., p. 81;. part of the tin oxidizes at the expense of the oxide of copper and dissolves without coloring the glass, while the resulting suboxide of copper makes the glass red and opaque. The lightness of the red color depends upon the freedom of the glass from other coloring oxides. S. Ph. may be employed in place of borax with advantage. When there is only a trace of copper, as in silver lead obtained on, the large scaje, or in lead reduced from cupreous litharge or abstrich, this method does not always afford a red bead, while in presence of ■2:,o plattnee's blowpipe analysis. Antimony the cold glass is gray or black, and opaque. In such cases tte alloy must first be fused in 0. F. alone on coal, until all the antimony is volatilized, then most of the lead must be dissolved in vitrified boracic acid, vide quantitative copper assay, p, 392, and the remaining globule treated some time with S. Ph. on coal in 0. F., after which the glass bead is fused with tin in E. F. A trace of ■copper will render the cold bead distinctly red and wholly or par- tially opaque. When the alloy contains much nickel, cobalt, iron, and arsenic, most of the Co and Fe can be separated by borax on coal in K. F. and recognized by the color of the glass, p. 185, after which lead may be added, and this, with the remainder of the cobalt and iron, dis- solved in boracic acid, while the greater part of the arsenic will volatilize. The remaining cupriferous nickel button, which may contain some arsenic, is treated in 0. F. with S. Ph., which will be dark-green while hot, becoming lighter on cooling, and when quite cold fine green, if not containing too little copper. The final green results from the yellow of the nickel and the blue of the cojiper. To detect a little copper in tin it is treated with successive portions ■of S. Ph. on coal in 0. F., until nearly all the tin is separated and the remaining button imparts a bluish-green color to the glass, when a bit of pure tin is added and the glass treated a short time in R. F.; on cooling the bead becomes red. Compounds of copper with sulphur and with metallic gj{p£'jeg. sulphides are roasted at a moderate heat on coal, p. 78, with the 0. F. and E. F. alternately, until all the sulphur is removed, and the product is then treated with soda in E. F., yielding metallic copper, or dissolved in the glass fluxes and tested for copper with tin on coaL If other easily reducible metallic oxides are present, the reduction Avith soda affords an alloy of copper and other metals, which, if not in one button, may be obtained by washing away the slag and coal in the mortar, and is then refined with lead and boracic acid on coal, p. 392, provided it contains no lead. When it is desirable to avoid refining, the alloy may be simply tested for copper with borax and S. Ph. as above described under metallic compounds. In case only fiesquioxide of iron is present, the reduction does not afford an alloy, but the copper and iron are obtained apart and can be clearly dia- tinguished after washing, by the aid of the magnifier and the magnet. The presence of binoxide of tin, as in roasted stannite, causes a white, brittle alloy, which, treated for some time beside .'la BXAMINATIOlir FOE COPPER. 351 S. Ph. bead in 0. F. on coal, renders the bead red and opaque on cooling. Should the roasted substance contain other coloring oxides besides copper, excepting those of bismuth and antimony, it will always yield the copper reaction as well as the other reactions, if dissolred in the fluxes in 0. F. and then treated with tin in R. F., unless there is too little copper. In presence of much bismuth or antimony, however, the bead treated with tin becomes dark-gray to black on cooling and the red copper-'-nlor is entirely concealed. When there* is but little bismuth or antimony the bead frequently becomes only brownish-gray. If a gray or black bead is obtained, the roasted sub- stance must be fused in R. F. on coal, with a mixture of soda, borax, and test lead. The resulting button is then treated alone on coal, to volatilize the antimony, and afterward with boracic acid, until either a pure copper button remains, or all is dissolved and the copper has imparted a blue, green, or red color to the boracic acid; or else the copper buttor, after being freed from most of the lead and bismuth by means of the boracic acid, is tested with S. Ph. and tin as above. When a substance consisting, for instance, chiefly of sulphide of iron, contains so little copper that it yields no reaction with borax or S. Ph. and tin, a larger quantity, about one hundred milligr., must be roasted thoroughly and then moistened on coal with a drop of hydrochloric acid — and next treated in the tip of the blue flame, p. 77. Mere traces of copper are thus detected. The oxides of copper can be very easily recognized by testing with the glass fluxes, and by reduction with soda or oxalate of potassa for the metal. AVhen other metallic oxides or acids are also present as in various metallurgical products, the remarks under iron, p. 185, are to be borne in mind. Antimony may be recog- nized partly by its coat on coal and partly by the black bead af- forded with S. Ph. and tin. Silicates and '^^^ silicates and other salts of copper dissolve in 0. F. other salts, jjj ^jjg g]g^gg fl^xeB to green beads, blue on cooling, if free from other coloring oxides. The greater part of the silica remains undissolved in S. Ph. Treated with tin on coal the beads become red and opaque on cooling. To obtain metallic copper, sulphates and arsenates must first be thoroughly roasted on coal, and the product, as well as the remain- ing salts, then reduced with soda and borax, when the copper generally unites to a single button, while the diflBcultly reducible oxides are dissolved , in the borax. Phosphate of copper, however. 252 plattner's blowpipe akalysis. only yields the whole of its copper when a hit of very fine iron wire is added to reduce the phosphoric acid. When a compound of sulphates or arsenates of copper, nickel, cobalt, and sesquioxide of iron is roasted, the sulphur is volatilized, but part of the arsenic remains as arsenate of nickel, and when the roasted substance is reduced with soda and borax, copper, nickel, and arsenic unite to a fusible button, while the oxides of co^")alt and iron dissolve in the borax. If the reduced button contains copper it will at once impart to S. Ph. in 0. F. a green color, becoming some- what lighter on cooling and due to nickel and copper. The copper may further be tested for with tin. The suboxide of copper in slags cannot be easily detected by borax and S. Ph., because it forms frequently a very trifling ingredient; and especially when other coloring oxides conceal the copper re- action. It is therefore best to evaporate the finely powdered sub- stance to dryness in a porcelain dish with hydrochloric acid, stir the residue with a drop of water and test the mixture on wire for the azure-blue flame. In the forceps cupriferous minerals impart a green tinge to the flame, which is azure-blue in presence of chlorine, but afterward becomes green. When much lead is also present the flame is blue with a green tip. Should copper not he thus simply detected it may be found by moistening the substance first with hydrochloric acid, when the resulting chloride of copper afl'ords an azure-blue, or greenish, and in certain cases reddish-blue color. Silicates, e. g. slags, must be finely powdered, moistened with hydrochloric acid in a porcelain dish, dried over the flame, the powder stirred to a thin paste with water and then fused B. B. on platinum wire, when the azure-blue color will appear, if copper is present. h. Blowpipe characteristics of the foregoing cupriferous minerals. Metallic copper fuses to a bright, bluish-green globule, which ia covered with black oxide on cooling. In 0. F. shows oxide of copper reactions with the fluxes. ARSENIDE OF COPPER. Wiitneyite, algodonite, and domeykite yield no sublimate in the closed tube. On coal they fuse readily to a bright globule, evolve arsenical fumes, and then react for copper with the fluxes. Condurritt at flrst yields water in the matrass, then arsenoua COPPER — SELENIDES — WITH SULPHUR Al^^D SULPHIDES. 253 ncid, and assumes on the surface a silver- white. color, inclining to bluish. In the open tube yields arsenous acid. On coal fuses easily, evolves a strong arsenic odor and yields a yellowish, metallic mass, which reacts weakly for iron with borax in K. F: and then shows copper, SELEITIDES. Berzelianite fuses readily to a gray, somewhat sectile button and evolves an odor of selenium. In the open tube a red, pulverulent sublimate of selenium, bordered by a crystalline, easily volatile sub- limate of selenous acid. Eoasted and reduced with soda it yielda copper. (Berzelius.) Umangite behaves similarly. Crookesite fuses very readily to a greenish-black, shining enamel, and colors the flame strongly green. (Dana.) COPPER COMBINED WITH SULPHUR AKD WITH OTHER SULPHIDES. Chalcocite yields nothing in the closed tube; in the open tube sulphurous acid. 0n coal fuses readily to a globule, which spirts and evolves sulphurous acid. The powder reduced with neutral oxalate of potassa yields copper and sulphide of potassium, which sinks into the coal and is strongly hepatic. Digenite yields traces of water and a sulphur sublimate in tho closed tube. On coal yields some sulphur, otherwise like chalcocite. Covellite yields traces of water and much sulphur in the closed tube. In the open tube sulphurous acid and, if quickly heated, sulphur. On coal burns with a blue flame, then behaves like chalcocite. Bornite only becomes darker in the closed tube ; in the open tube yields sulphurous acid. On coal fuses easily to a brittle, magnetic globule, with grayish-red fracture. The roasted powder yields iron and copper reactions. Tennantite sometimes decrepitates slightly in the closed tube and yields sulphide of arsenic. In the open tube yields sulphurous and arsenous acids. On coal fuses easily, with intumescence and evolu- tion of sulphur and arsenic fumes, to a dark-gray, magnetic globule. The roasted powder reacts for iron and copper, and by reduction yields copper buttons and metallic iron. No coat is perceptible on the coal. Julianite behaves similarly. Kupferbhnde, from Junge hohe Birke and Alte Mordgrube, near Preiberg, decrepitates very strongly in the closed tube and yields a little sulphur and, at a higher heat, sulphide of arsenic. On coal 25-4 PLATTXEIl'S BLOWPIPE ANALYSIS. like tennantite, but is distinguished by afiEordinga coat of arsenous acid and, with R. F., an abundant zinc coat. Roasted in powder it reacts for copper and iron, and by a reduction assay affords a strong zinc coat, while copper and iron remain after the coaly matters are washed away. Upon separating the iron with the magnet and cupelling the copper with lead, a little silver is obtained. Enargite decrepitates with some violence in the closed tube and yields a sulphur sublimate at a gentle heat; more strongly heated it fuses to a button, and sulphide of arsenic is given off. In the open tube the powder yields sulphurous and arsenous acids, the latter mingled with oxide of antimony. On coal the powder fuses readily to a globule and affords slight coats of arsenous acid and oxide of antimony. On pulverizing and roasting this globule, dissolving it in borax and reducing out the copper, a little iron may be detected by the greenish color of the borax glass in R. F. and the yellow color as- sumed by it when fused again in 0. F. on platinum wire. Luzonite behaves the same way. Famatinite decrepitates in the matrass and yields a sublimate of sulphur ; at a- higher temperature, some aptimony sulphide. In open tube, sulphurous acid and antimony fumes. A little of the coating is volatile on heating. On coal, n strong antimony coat, and a black, brittle button, easily showing copper. Barnhardtite and liomiclilin yield a sulphur sublimate in the closed tube; otherwise like bornite. Tetrahedrite sometimes decrepitates in the closed tube, fuses, and strongly heated B. B. yields a dark-red sublimate of sulphide with oxide of antimony, or an orange one of sulphide of arsenic, or a mixture of both. A- low red-heat suffices to produce a dark-gray to black sublimate of Hg S, if present. In the open tube fuses and yields copious antimonous fumes and sulphurous acid, frequently also arsenous acid; the residue is black and infusible. If HgS is present a mirror of mercury forms be- fore any considerable antimonous fumes appear ; by too rapid heating black Hg S is sublimed. On coal fuses readily to a globule and yields a copious antimony coat, while with a good R. F. a second coat is formed, yellowish while hot, white on cooling, and showing zinc with cobalt solution, p. 21;?. In presence of lead this cannot always be detected. Arsenic is recognized by the odor, unless in too small quantity, when some soda must be mingled with the powdered mineral and the whole treated in R. F. The sulphur is thus kept back and the arsenic alone COPPEE WITH SULPHUa AND SULPHIDES. 355 velatilized. The globule remaining after treating the mineral alone on coal is pulverized, roasted and tested with glass fluxes and with soda, when it yields reactions for iron and copper. Keduction with Boda and borax sometimes affords niccoliferous copper. To detect a very little mercury it may be necessary to heat the fine powder, mixed with three Tolumes of dry soda, or neutral oxalate of potassa, in a matrass. Silver is found by an assay with test lead, vide quantitative silver assay. Sometimes silver is shown by the gradual reddening of the white antimony and zinc coat. Bismuth would be detected as directed under this metal. Lautite decrepitates strongly, melts easily, gives first in the matrass some sulphide of arsenic, then arsenic; in the open tube, arsenous and sulphurous acids. On coal, after long blowing, a cop- per button, which almost always leaves silver when cupelled with lead. Binnite yields in the closed tube sulphide of arsenic, in the open tube sulphurous and arsenous acids. On coal yields an arsenic coat and odor, and fuses with spirting to a black globule, surrounded by a zinc coat. With the fluxes gives copper reactions. Annivite behaves like plumbiferous tetrahedrite; bismuth can only be found by the wet way. Stylotypite, like an argentiferous antimonial tetrahedrite. Chalcopyrite decrepitates in the closed tube, yields sulphur and becomes dark or tarnished ; in the open tube evolves sulphurous acid copiously. Fuses on coal, spirting and throwing off sparks, to a black, rough, magnetic globule, with a dark-gray fracture. Well roasted gives iron and copper reactions; by reduction with soda yields iron and copper. ChalcostiUte decrepitates in the closed tube, fuses, and at a high heat yields a little sulphide of antimony. In the open tube evolves sulphurous acid and copious antimonial fumes. On coal fuses readily, with evolution of antimonial fumes, to a globule, which tested with borax shows iron. The remaining globule yields copper with soda. Cubanite yields traces of sulphur in the closed tube ; in the open tube sulphurous acid. Fuses readily on coal, with evolution of sulphurous fumes, to a magnetic globule. Lead, if present, pro- duces a feeble coat. Roasted in powder it yields iron and copper reactions with the fluxes, and metallic iron and copper by a reduo tion assay. 256 plattner's blowpipe analysis. Epigenite in the matrags at first yields sulphur, then sulphide of arsenic, like enargite. On coal, a strong arsenic reaction, and a magnetic slag containing cop- per buttons ; with soda a, white button of copper arsenide in a magnetic slag. COPPER COMBINED WITH CHLORINE. Atacamite in the closed tube yields water rather abundantly and gives a gray sublimate, becoming grayish-white on cooling. Fuses on coal, afEording an azure-blue flame with a green tip, and gives two coats, one brownish and one grayish-white. It is reduced to a copper button, surrounded by some slag. Under K. P. the coats change their position, and show the azure-blue flame of chloride of copper. Nantokite fuses in the matrass to a dark fluid, and on longer heating gives a grayish-brown sublimate, grayish-white in cooling. Fuses easily on coal, colors the flame intense greenish-blue, forms a white, volatile coat, and leaves a dark copper button. The coat disappears with an intense blue flame, leaving the coal ash red (Cu' 0). OXIDES OE COPPER. Cuprite in the forceps fuses and colors the flame emerald-green; moistened with hydrochloric acid yields an azure-blue flame. On coal blackens, fuses and is reduced to copper, which is coated with a thin film of black oxide on cooling. Melaconite behaves quite similarly; Si 0" and Fe'' 0' can be easily detected. Kupferschwdrze sometimes yields much water in the matrass. Alone on coal is reduced to a copper button, frequently surrounded by slag. With the fluxes affords reactions for copper, iron, and manganese. OXIDE OF COPPER COMBINED WITH ACIDS. The sulphates of copper behave as follows: — BrocUantite yields water and sometimes blackens in the matrass. Strongly heated, it evolves sulphurous and sulphuric acids. On coal is reduced with effervescence to a copper button, covered with a black film. With soda on coal, a hepatic mass and metallic copper. The glass fluxes show Cu 0. Langite behaves similarly. Both minerals are insoluble in water. Chafcanthite swells in the matrass, yields water and whitens. COPPER — OXIBES WITH ACIDS. 257 "When mixed with coal dust and heated in the closed tube it evolves sulphurous acid copiously. On coal colors the flame green, fuses and is reduced with effer- vescence to a copper button, coated with sulphide of copper. When well roasted reacts for copper and sometimes iron with the fluxes. With soda yields copper. Among the phosphates, pseudomalacMte, dihydrite, ehlite, and libethenite behave as follows : In the matrass they yield water, blacken, and sometimes decrepi- tate if quickly heated. After ignition in the matrass a fragment heated in the forceps fuses without coloring the flame perceptibly ; the fused globule is black and has a crystalline surface. Gradually heated on coal (in powder if they decrepitate) they blacken and fuse to a button, with a core of metallic copper. With the glass fluxes they react like oxide of copper. A sufficient quantity of soda causes their reduction to metal in a strong flame, but with a little soda they swell up and fuse to a globule. This phenomenon is repeated on each fresh addition of soda, until finally a swollen mass results, which only fuses in a strong flame, spreads out, sinks mostly into the coal, and leaves metallic copper. Arsenic acid may be detected in some of them by fusion with soda. Berzelius has proposed a test for phosphoric acid in these minerals, founded upon the peculiar behavior of phosphate of copper with metallic lead. When to the phosphate fused on coal an equal volume of lead is added and the whole melted together for some time in a good flame, the copper separates as metal, around which is a fluid mass of phosphate of lead, which is crystalline when cold. If the metallic button is separated from this new compound and the latter treated alone in E. F., a perfectly round bead finally results, which on cooling crystallizes with large facets and usually has a red color. On' 0. This behavior shows that phosphoric acid has a greater affinity for oxide of lead than for oxide of copper. Tagilite, probably like the preceding. Thrombolite yields much water and blackens in the matrass. In the forceps fuses easily, coloring the flame at first azure-blue, proba- bly from chloride of copper, but afterward emerald-green. On coal fuses easily to a black globule, which finally spreads out and shows metallic copper buttons. With glass fluxes gives only copper reac- tions; with boracic acid and iron afibrds phosphide of iron. The carbonates of copper behave as follows : Malachite and azurite yield water and blacken in the matrass. Fuse to a button on coal and are reduced to metallic copper. With 358 PLATTl>rEK'S BLOWPIPE AKALTSIS. the fluxes behave like oxide of copper, and dissolve with efferves- cence in hydrochloric acid. The arsenates behave as follows: Glinoclasite, from Cornwall, yields a little water in the matrass. On coal fuses with deflagration, evolving arsenic fumes, to a copper button, having a grayish fracture, due to a little arsenic. This button, melted again in 0. P., becomes perfectly malleable. With glass fluxes, like oxide of copper. OVwenite yields some water in the matrass. In the forceps fuses to a globule and colors the flame bluish-green. On cooling it has a crystalline appearance. On coal it fuses, with deflagration and evo- lution of arsenical fumes, to a somewhat brittle, brown-metallic globule, with a white fracture, which treated with lead yields the phosphoric acid reaction described on p. 357. The detached button of lead and copper leaves pure copper when treated with boracic acid, p. 392. CornwalKte yields water in the matrass. On coal evolves arseni- cal fumes, and fuses to a globule of copper surrounded by a brittle crust. Erinite frequently decrepitates very strongly and yields much water in the matrass. On coal in powder is reduced, with evolution of arsenical fumes, to a brittle globule with a grayish fracture, which in 0. P. affords pure copper. In presence of phosphoric acid a tri- fling crystalline slag remains with the copper. Euchroite yields considerable water and assumes a darker green in the matrass; on coal, like clinoclasite. Chalcophyllite decrepitates very strongly in the matrass, yields much water and breaks into fine, olive-colored scales. On coal like the foregoing. Tyrolite decrepitates, yields considerable water and blackens in the matrass ; the assay afterward fuses to a steel-gray bead in the forceps. On coal evolves arsenical fumes and fuses to a gray scoiia, in which copper globules are formed by E. P. After reducing out all the copper with borax and soda and then dissolving the slag in hydrochloric acid, considerable lime may be detected by adding oxalic acid to the solution, after it is made ammoniacaL The lime is present as carbonate, as is shown by the effervescence of the mineral with warm nitric acid. Trichalcite behaves like cornwallite. Liroconite yields much water and becomes dark olive-green iu the matrass. In the forceps fuses and colors the flame bluish-green. On coal fuses, with formation of bubbles and evolution of arsenical fumes, COPPEE — OXIDES WITH ACIDS. 259 to a dark brown slag, which contains copper glohules and with borax and soda affords an arsenical copper batton. In the slag alumina, partly combined with P" 0', can be detected. Conichalcite decrepitates strongly, yields water and blackens in the matrass. On coal deflagrates evolres a slight arsenic odor, and forms a red slag, which has an alkaline reaction on litmus-paper. In the forceps fuses, coloring the flame at first strongly green, but afterward only green at the extremity, while near the assay it has a feeble, light-blue color. With borax in 0. F. a yellowish -green bead; b]ue on cooling. With S. Ph. and lead on coal in R. F. affords a glass, dark-yellow while hot and chrome-green on cooling (vanadic acid). With soda on coal in R. P. effervesces, evolves arsenical fumes and fuses to a globule ; on longer blowing affords a copper button and a' white, earthy mass. Lime and phosphoric acid may be detected by the wet way. Volhorthite yields water and blackens in the matrass. On coal yields a black slag with copper buttons; with soda, copper; the glass fluxes give copper reactions. The borax bead reduced on coal with lead is chrome-green (V 0'). Cuprotungstite blackens B. B., fusing easily to a black, some- what porous globule with uneven surface. The S. Ph. bead re- duced on coal beside lead is sapphire-blue (W 0'), or blood-red (W 0' + Fe'^ 0=). Ohalcomemte fuses and yields water in the matrass. In the forceps an intense cornflower-blue flame. On ooal fuses to a slaggy mass, colors the flame blue (Se) and gives selenium fumes and coat. With soda, copper. The silicates, dioptase, and chrysocolla yield water and blacken in the matrass. In the forceps are infusible, but color the flame intensely green. With the fluxes yield copper reactions, and with S. Ph. a silica skeleton. On coal they blacken in 0. P., become red in R. P., and with soda in R. P. yield copper buttons. With a certain amount of soda they melt in 0. P. on coal with effer- vescence to a globule which when cold is opaque and has a red fracture. With more they form in R. P. a slag, partly sinking into the coal, partly spreading out; it contains a number of small cop- per buttons; c. Metallurgical products. The method of examining metallurgical products for copper may be inferred from the general remarks on pp. 250 and 351. 260 plattnee's blowpipe analysis. 13. Meecurt, Hg. Its occurrence in the mineral kingdom and in metallurgical products. Mercury occurs under the following circumstances in nature: a. Metallic in Native mercury, — Hg, sometimes containing Ag; Amalgam,— Ag' Hg^ with 73.5 Hg and 26.5 Ag; Ag Hg with 64.9 Hg and 35 Ag; Kongsbergite, Ag" Hg with 5 Hg, and 95 Ag; Arquerite,— Ag'= Hg, with 13.5 Hg and 86.5 Ag. b. With selenium in Tiemannite, from Clausthal and Tilkerode, — Hg Se, with 71.6 Hg Selenide of mercury also occurs in other seleniferous minerals in the Harz, especially in Lehrbachite and Seletiquecksilberkupferilei, vide lead. Also combined with sulphide of mercury in Onof rite, — Hg Se + 4 Hg S, with 82. 8 Hg. Selenite of suboxide of mercury also occurs in this locality. c. Combined with sulphur in Cinnabar, — Hg S with 86.2 Hg, but not always quite free from foreign substances, viz.: Cu' S, Fe" 0°, Mn" 0°, and earthy matters ; Hepatic cinnabar, a mixture of cinnabar, idrialite and earthy matters ; CoraUinerz from Idria contains much phosphate ol lime, alumina and iron. Guadaloazarite, — 6 Hg S, Zn S ; Mercurial tetrahedrite, vide copper. d. Combined with chlorine in Calomel {horn quicksilver),— Kg' GV, with 84.9 Hg. Bordosite, — Ag CI+ Hg' CI", with 50.3 Hg, deducting intermingled mercuric oxide. e. Combined with iodine in Cocoinite from Mexico, — Hgl». Mercury also forms an ingredient of certain amalgamation prod- ucts and residues, including : gold and silver amalgam ; unwashed amalgamation residues, which frequently contain finely-divided amalgam and subchloride of mercury. When the ores contain lead or copper the residues may often contain a little lead and copper amalgam. EXAMINATION FOR MERCUKY. 361 Examination for Mercury, Including the blowpipe characteristics of the foregoing minerals, a. General examination for mercury. Compounds of mercury with gold and silver, including native and artificial amalgams, and also residues not yet purified from silver, copper, and lead amalgam by washing, are heated over the spirit-lamp in a matrass formed by blowing a bulb on the end of a glass tube, Fig. 74. Generally a bit of amalgam as large as a millet-seed will suflBce, but in case of the residues from amalgamation the bulb should be at least half filled. Any water mechanically combined will be expelled by the first action of the heat and should be wiped away with blotting paper. On heating Fig. 74. to redness the mercury separates in vapor, which condenses on tiie -colder part of the tube at a to small metallic globules, that cannot be mistaken -for any other metal. The metals and residue in the mat rass may then be further tested for gold, silver, etc. Selenide of mercury may be recognized by the lustrous, crystalline, gray sublimate formed in the neck of the matrass. If mixed with much soda the mercury separates in globules, leaving the selenium combined with sodium. Combined with sulphur, as in cinnabar, mercury aflfbrds a black sublimate, which assumes a red color by friction. Powdered cin- nabar heated with five volumes of soda, previously dried by bringing it to incipient redness in the platinum spoon, yields a sublimate of metallic mercury and a little cinnabar, while the sulphur remains combined with sodium. If neutral oxalate of potassa, or, better still, a mixture of the oxalate with cyanide of potassium is employed, metallic mercury alone is obtained. Artificial cinnabar, or vermilion, if adulterated with minium, leaves in the matrass a residue of sulphide of lead, which can be recognized on coal. The same remarks apply to an admixture of sulphide of antimony. When sulphide of mercury is combined with other sulphides, as in certain varieties of tetrahedrite, even when very little is present, the test in the matrass afibrds, by the first action of the heat, a black sublimate of this sulphide, because it is so volatile that it can readily be separated from the other sulphides by an elevated temperature. Upon mixing the powdered substance with neutral oxalate of potassa 262 plattnek's blowpipe analysis. and cyanide of potassium, and heating it to redness in a narrow- necked matrass, metallic mercury separates and condenses on the neck to a gray coat, which may be united to a globule by gently tapping on the glass, unless too little mercury is sublimed. Should there be so little mercury that no film can be detected with certainty, the assay may be repeated and the end of an iron wire wrapped about with a bit of pure gold leaf held near the mixture while heating it. The gold will become entirely white, or at least very perceptibly so, if the slightest trace of mercury is present, cuorideof Combined with chlorine, mercury affords a white mercnty. sublimate in the matrass, or if mixed with dry soda or neutral oxalate of potassa, metallic mercury Tolatilizes on heating, leaving a chloride of the alkali.* To detect small quantities of the chlorides of mercury in substances it is only necessary to heat them wiCh soda or oxalate of potassa, observing the directions given for detecting a trifling amount of sulphide of mercury. Iodide of mercury (Hg I') fuses very easily in the matrass and afEords a crystalline, yellow sublimate, red on cooling. Subiodide of mercury Hg"!" fuses and sublimes unaltered, when quickly heated; if slowly heated, it is decomposed into mercury and the iodide. In the matrass with soda or neutral oxalate of potassa both compounds yield mercury. The oxy-salts of mercury are also best decomposed by saite. ignition in the matrass with perfectly dry soda, or neutral oxalate of potassa, which causes the separation of metallic mercury. i. Blowpipe characteristics of the mercurtferous minerals above named. Native mercury sublimes in the matrass and condenses to small globules, which can be readily caused to unite; if too strongly heated it boils and spirts. Any silver present wiU remain behind and can then be cupelled with lead, vide silver. Amalgam, and arquerite gradually heated to redness in the mat- rass, afford mercury and leave spongy silver, which may be fused to a button on coal, or if impure may be cupelled. * Mercuric chloride fuses at first ; mercuroua cliloride volatilizes direct. To insure complete decomposition a large excess o£ the reducing agent must be em- ployed. EXAMINATION FOE MERCUKT. 263 MEBCUBT COMBINED WITH SELENIUM. Tiemannite decrepitates in the closed tube, swells and fuses, vola- tilizing completely when pure and forming a black sublimate, brown- ish-red at the side farthest from the assay. The residue from impure fragments reacts for iron and silica with fluxes. The addition of considerable soda causes mercury to separate. In the open tube it affords a selenium odor and a black sublimate, followed by a reddish-brown one and then a white sublimate of selenite of mercury, sometimes fusible to drops like tellurous acid. On coal it volatilizes with an azure-blue flame and affords a lustrous metallic coat, surrounded by a dark-brown coat. (Kerl.) Onofrite (Selenschwefelquecksilber), according to H. Eose, volatil- izes unchanged, yielding a black sublimate of mixed sulphide and selenide of mercury. With soda it affords mercury and on coal diffuses a selenium odor. SULPHIDE OF MERCUKT. Cinnabar yields in the matrass a dark sublimate, which gives a red streak. If there is any residue it occasionally reacts for iron, copper, and lead. In the open tube it affords sulphurous acid and mercury, but if quickly heated part of it sublimes unchanged. On coal volatilizes completely if pure, yielding, with care, a gray- ish-white coat, showing mercury globules under the magnifier. Hepatic cinnabar affords in the matrass a very dark sublimate of oinnabar, evolves a distinct sulphuretted hydrogen odor and leaves a black coaly mass, which on ignition in the open tube, or on platinum foil, gradually disappears, leaving only a trace of earthy matter. Guadalcazarite in the matrass gives a gray to black sublimate of mercury with sulphide and selenide of mercury. In the open tube yellowish zinc oxide remains. On coal, a selenium odor; on longer blowing, a zinc oxide coat with a brown border of cadmium oxide. Calomel yields the reactions of mercury and chlorine, as given on p. 362. On coal volatilizes and forms a white coat, and with S. Ph. and oxide of copper shows chlorine, vide chlorine. Iodide of mercury (artificial) yields violet iodine vapors when heated with bisulphate of potassa in the matrass. See also under the general examination for mercury. 264 plattner's blowpipe analysis. c. Metallurgical products. The essential points regarding the examination for mercnry in thcBe products are giyen under the general examination. 14. Silver, Ag. Its occurrence in the mineral kingdom and in metallurgical products. Silver occurs in nature : — a. Metallic and alone in Native Silver, — Ag, sometimes with a little Sb, As, Hg, Co, Fe, On, and Au. b. Comhined with other metals : a. With gold in Native gold, vide gold. /8. With iismuth in Chilenite, when pure, Ag'° Bi, with 83.9 Ag and 16.1 Bl ■y. With mercury in ^.malgam and arquerite, vide mercury. S. With antimony in Dyscrasite (antimonial silver), of varying composition; Ag" Sb, with 94.1 Ag; Ag* Sb, with 84.2 Ag; Ag" Sb, with 72.6 Ag; Ag'Sb, with 63.9 Ag; e. With arsenic in Bittingerite, — h% As, and said to contain some Se ; 57.7 Ag. Arsenic silver (arsensiCber) from Andreasberg, containing, according to Bammels- berg, about 9 per cent. Ag, is perhaps a mixture of arsenopyrite, arsenical iron and dyscrasite. c. With tellurium in Hessite, — Ag' Te, with 62.8 Ag, and occasionally Au and traces of Fe; Petzite, sylvanite, calaverite, Weisstellur, vide gold. d. Combined with selenium in Naumannite, one compound = Pb Se + 13 Ag' Se, the other = Ag' Se + 5 Pb Se; pure Ag' Se containing 73.15 Ag; Eucairite, — Ag' Se + Cu' Se, with 43.1 Ag and 25.3 Cu, and traces of Tl. e. With sulphur and other sulphides in Argentite {silver glance), and acanthite, — Ag' S, with 87.1 Ag; Stephanite {brittle silver ore), — 5 Ag' S, Sb' S', with 68.36 Ag and occasionally a little Fe, Cu, and As; SILVER. 265 Polybasite,— 9 (Cu, Ag)' S + (Sb, As)' S', with 64 to 73 Ag and 10 to 3 Cu, occasionally a little Fe and Zn; Jalpaite,— 3 Ag» S + Cu" S, with 71.7 Ag and 14 Cu; Rittingerite, probably a compound of sulphide of silver and anti- mony (Dana); Boliviaiiite, according to T. Eichter, antimonial sulphide of silver, with 8.5 per cent. Ag (Dana); Stylotypite,— 3 (Cu', Ag, Pe) S + Sb' S' (Dana); Proustite {ruhy silver, pt., ligld red silver ore), — 3 Ag» S, As' S% with 65.4 Ag ; occasionally a little Sb replaces some As; Xanthoconite is of the same composition as proustite ; Pyrargyrite [ruly silver, pt., dark red silver ore), — 3 Ag' S, Sb' S% with 59.78 Ag; usually with a little As' S''; Pyrostilpnite {fire-blende), — like pyrargyrite; Stromeyerite, — Cu' S + Ag' S, with 53.1 Ag and 31.2 Cu, sometimes a little Fe ; it apparently occurs mixed with chalcocite in some localities, so that the Ag may sink to a few per cent, Miargyrite,— Ag' S, Sb' S', with 36.9 Ag and a little Cu and Fe; Sternbergite,— Ag' S, 3 Fe S, Fe' S', with 34.3 Ag; Argentopyrite is similar ; Brongniardite,— Ag' S, Pb S, Sb' S'; 26.1 Ag; Freieslebenite,— 5 Ag' S, 7 Pb S, 5 Sb' S', or 3 Ag' S, 4 Pb S 3 Sb' S', with 22.5 to 23.5 Ag; in the Freiberg variety 1.2 per cent. Cu and a little Fe; diapliorite has the same composition ; Lichtes Weissgiltigerz from Freiberg, — 4 R S + Sb' S'; R = Ag, Pb, Fe, Zn, with 38 Pb, 5.7 Ag, and traces of Cu; Argyrodite,— 4 Ag' S + Ge S', with 74 to 76 Ag, and a little Fe, Zn, Hg. Canfleldite,— 4 Ag' S + (Ge, Sn) S', with 74.1 Ag, and some Zn, Fe ; Sundtite,— (Ag, Cu)' S + Fe S + 3 Sb' S', with 11.8 Ag ; Matildite, sohirmerite, vide bismuth ; Tetrahedrite (so-called dunkles Weissgiltigerz, with 18 to 31.8 Ag), vide copper. e. Combined with chlorine, bromine and iodine in Oerargyrite {Jiorn silver),— Ag CI, with 75.2 Ag; sometimes mixed with Fe' 0' and earthy matters ; Huantajayite is Ag 01 with NaCl; Embolite, — Ag CI and Ag Br in varying proportions : 3 Ag CI + Ag Br, with 69.8 Ag (microbromite), 2AgCl+AgBr " 68.2 " 3 Ag CI -I- 2 Ag Br, " 66.9 " (embolite), 4 Ag CI + 5 Ag Br " 64.3 " (megabromite), Ag CI + 3 Ag Br « 61.0 " 266 plattner's blowpipe analysis. Bromyrite, — Ag Br, with 57.4 Ag ; lodyrite, — Ag I, with 45.9 Ag; Tocornalite, — silver iodide with 4 per cent. Hg ; Cuproiodargyrite,— Ag I + Cu I, with 25.6 Ag. Silver occurs in metallurgical products as follows : a. Metallic in Eefined silver, frequently with traces of Pb, and sometimes Au and Cu; Brightened silver, containing a little Pb, Cu, and sometimes Bi, Sb, As, and Ni; Cement silver from the " extraction " of argentiferous ores and products; it frequently contains more or less Cu and trifling quantities of other metals ; Retort silver, often containing more or less Cu, traces of Au, Ni, Coj and, before refining, also Fe, Zn, Sb, Pb, As, and Hg ; Amalgam, usually containing the ingredients of the foregoing product ; Raw, or silver lead, almost always containing trifling quantities of other metals, vide lead. A little Ag also occurs in black copper, raw copper, and refined copper, vide copper; and in many specimens of lead, vide lead. b. Combined with sulphur it occurs in trifling quantity in the various matts and speiss-like products from smelting silver, lead, and copper ores, and in certain furnace deposits, vide iron. c. As oxide in very small quantities in the products of cupellation, viz., litharge, abzug, abstrich, and cupel bottoms or hearth, vide lead. Here should also be mentioned the test mass, or bottom of the silver refining hearth. Slags containing silver often owe its presence chiefly to fine, disseminated particles of argentiferous matt, although some slags contain silicate of silver. Ezamination for Silver, Including the blowpipe characteristics of the above-earned minerals and products. a. General examination for silver. Compounds of silver with metals, volatile at a high heat, aa antimony, lead, and bismuth, yield a coat on coal. After nearly the whole of these metals have been volatilized by long blowing, the coat bscomes reddish to carmine-red from oxide of silver, if there is not too little of that metal present, and the remaining EXAMINATION FOR SILVER. 267 button shows a more or less pure silver color.* This reddening of the coat is highly characteristic and may always be regarded as indi- cating silver. In combination with much lead or bismuth, silver is found by cupellation, with addition of test lead, if that is made necessary by the presence of other oxidizable metals, vide quantita- tive silver assay. When silver containing arsenic is treated alone, on coal, the arsenic volatilizes and may be recognized by its odor. Selenium behaves similarly. Tellurium, if present in considerable quantity, partly volatilizes and coats the coal, but part of it remains persistently with the silver and can only be removed by treating the compound, pulverized as much as possible in the K. F., with soda, or neutral oxalate of potassa. Telluride of sodium (potassium) forms and goes into the coal, leaving little globules of silver. Mercury combined with silver can be removed by ignition on coal, or in the matrass; on coal the silver fuses to a button, in the matrass it forma a porous residue. If the silver is combined with much gold and the alloy is fused in 0. P. with S. Ph. on coal, the silver oxidizes and is gradually dis- solved, rendering the glass opalescent when cold. By separating this glass from the gold button and treating it alone on coal in E. P., the oxide is readily reduced and united to a button of silver. When non-volatile metals, more easily oxidized than silver, are present, viz., copper, nickel, and cobalt, in not too small quantity, they may readily be detected by testing with borax or S. Ph. on coal, and frequently so far separated as to leave the silver with a pure surface. When present in large quantities they can only be entirely separated by cupelling the silver with test lead. Should these metals be present in so small proportions that no distinct reactions are obtained with the glass fluxes, a sufficient quantity of the silver is treated first on coal alone in 0. P. and notice taken of any coat that may be formed. After this the button is dissolved in nitric acid in a test tube, diluted with water, a few drops of hydrochloric acid added, and the whole well shaken, so that the chloride of silver may settle. When the fluid is clear a drop or two of hydrochloric acid is added, to ascertain whether it will produce any further cloudiness. If it does the whole must again be well shaken ; if not, the solution may be filtered at once, the filtrate heated to boiling in a porcelain vessel and a solution of potassa gradually added to feebly alkaline * These red coats consist perhaps of antimonate, plumbate or bismuthate of silver. 268 PLATTIfER'S BLOWPIPE ANALYSIS. reaction. By this means the other metals, present as oxides, are thrown down, and after filtration may he readily detected hy means of the glass fluxes. The chloride of silver can be reduced on coal with soda. Minerals and metallurgical products consisting of, or containing sulphides of metals, and which are to be directly examiried for silver, may be most advantageously treated according to the method given under the quantitative silver assay, and the silver lead cupelled. Most of the above-mentioned minerals containing sulphides show the presence of silver by the reddish coat formed on coal. The zinc oxide coat from zinc blende shows in some spots a feeble but distinct rose color if the silver amounts to a few tenths of a per cent. The surest way to find even the smallest amounts of silver in any sort of substance is by the method for the quantitative silver assay. d. Blowpipe characteristics of the argentiferous minerals enumerated above. Native silver fuses on coal to a bright globule, which has a silver- ffhite color on cooling. The presence of antimony causes a feeble white coat of antimonous acid, which afterward becomes red, p. 69. Arsenic, if present, is detected by the odor during fusion. With borax in K. P. on coal it sometimes affords a glass that reacts for cobalt and iron. Dyscrasite fuses very readily to a button on coal, affords a copious coat of oxide of antimony, which afterward reddens, and finally a rather pure silver button remains. Hessite fuses in the open tube, without affording very copious fumes. On coal fuses readily to a globule and yields part of its tellurium, coating the coal, p. 67; but the greater portion remains with the silrer. When cold the surface is covered with lustrous metallic globules. Fused in a fine state with soda, or neutral oxalate of potassa in R. F., the tellurium is separated, leaving the silver in little globules, which if cleansed from the coal and slag by washing, and then dis- solved in nitric acid generally leaves a little gold behind. 8ILTBB IK COMBIITATIOK WITH SELENIUM. Naumannite fuses and yields a trifling sublimate in the closed tube. On coal in 0. F. fuses quietly, but in E. F. intumesces, and SILVER WITH SULPHUR. 369 m solidifying glows again. With soda and borax affords a lustrous silver button (G. Rose). Eucairite. — In open tube like berzelianite, p. 353. On coal fuses with a strong odor of selenium, and affords a gray, soft, but not malleable, metallic button. Cupelled wil^h test lead, leaves a silyer button, and with the fluxes reacts strongly for copper (Berzelius). SILVER IN COMBINATIOK WITH SULPHUR. Argentite and acanthife fuse on coal in 0. P., with intumescence and evolution of sulphurous acid, affording at length a silver but- ton, which sometimes reacts for copper. If impure, a slag also results, which reacts usually for iron and sometimes for copper. With soda a silver button is very easily obtained. In the closed tube they fuse, but yield no sublimate. In the open tube much sulphurous acid, and on long heating the mass becomes coated with silver. Stephanite decrepitates in the closed tube, then fuses, and after some time yields a slight sublimate of sulphide of antimony. In the open tube fuses and evolves antimonous fumes and sulphurous acid. On coal fuses very easily, with spirting, coats the coal with oxide of antimony, and is converted into sulphide of silver, contain- ing but litle antimony. On long blowing the coat reddens and a silver button remains, sometimes with a scoria that reacts for copper and iron. Polybasite fuses with extraordinary ease in the closed tube, but yields no sublimate. In the open tube fuses and yields sulphurous and antimonous fumes. Under the magnifying glass, if As" S' was present, the sublimate is seen to consist of antimonous acid mixed with crystalline arsenous acid. On coal in 0. P. fuses very readily with spirting to a globule, which evolves sulphurous acid and coata the coal with oxide of antimony and, in presence of arsenic, arsen- ous acid. Long blowing occasionally produces a yellowish-white zinc coat near the assay, and finally a metallic, mirror-like button is obtained. The cold button has a black surface, and the white coat is somewhat reddened by oxide of silver. With S. Ph. the button behaves like cupriferous silver. Proustite fuses very readily in the closed tube and at incipient redness affords a slight sublimate of sulphide of arsenic. The residue has a dark, lead-gray, scaly fracture and feebly metallic lustre. In the open tube affords sulphurous and arsenous acids, with some 270 plattnee's blowpipe analysis. antimonous fumes, if Sb replaces some As. Fuses on coal wilt eToIution of sulphurous and arsenous fumes and coats the coal with arsenoas acid (and, in presence of Sb, with oxide of antimony) ; but later the fused globule behayes like sulphide of silver. This fused for some time in 0. P., or reduced with soda, affords pure silrer. Xanthoconite in the closed tube assumes a transient, dark-red color. More strongly heated fuses and then behaves like proustite. In the open tube and on coal like proustite free from antimony. Pyrargyrite fuses very readily in the closed tube, sometimes flying into small pieces at first, and at a continued red heat affords a sub- limate of amorphous tersulphide of antimony. Fuses in the open tube and evolves sulphurous acid and antimonial fumes. On coal fuses very readily with spirting to a globule, yields sulphide of anli- mony, coats the coal with oxide of antimony, and is converted iiiti: sulphide of silver, which obstinately retains some antimony. By long treatment in 0. F„ or reduction with soda, this affords pure silver. Any As replacing Sb can be recognized most surely in the open tube by long heating; minute crystals of arsenous acid form in front of the antimony oxide sublimate and are especially lustrous in reflected light. Pyrostilpnite; in the open tube and on coal like pyrargyrite. Stromeyerite fuses very easily in the closed tube; in open tube, evolves sulphurous acid, but no sublimate when pure. Fuses very readily to a globule on coal and in 0. F. evolves only sulphurous acid if pure. The fused globule has a metallic lustre, is half mal- leable, and has a gray fracture. With the fluxes reacts strongly for copper and sometimes feebly for iron. Cupelled with test lead it leaves a silver button and a dark-green, copper stain on the cupel. Jalpaite, like the preceding. Miargyrite decrepitates in the closed tube, fuses very easily and gives a film of sulphide of antimony. In the open tube evolves sulphurous acid and abundant antimonous fumes. On coal fuses very readily and quietly, with emission of sulphurous and antimo- nous fumes, to a gray globule, which finally in 0. F. changes to a bright silver button, while the antimony coat reddens. Treated with S. Ph. and tin, the button shows a feeble, but distinct reaction for copper. Sternbergite yields in the open tube only sulphurous acid; on coal fuses with evolution of sulphurous acid to a globule, which is covered with metallic silver and is magnetic. Eoasted in powder on coal and treated in E. F. with borax, gives a silver button, and a black, opaque glass, which reacts for iron. COMPOUNDS OP SILVER WITH CHLORINE, BROMINE, AND IODINE. 271 Freiedelenite in the open tube yit-lds sulphurous acid and antimo- nous fumes, the uon- volatile portions of which likewise contain anti- monate of lead. On coal fuses easily, forming at a certain distance a coat of oxide of antimony mixed with sulphate of lead, and nearer the assay a dark-yellow coat of oxide with autimonate of lead. The coat finally becomes very red and a silver button is left, which may be purified by treatment with boracic acid on coal. Lichtes Weissgiltigerz from Freiberg. Fuses in the open tube, and behaves like freieslebenite. On coal fuses very easily, spreads out, coats the coal strongly with oxides of antimony and lead, and leaves small, grayish-white, metallic buttons. The lead may conceal any oxide of zinc. Fused with borax in E. F. the metallic buttons unite to a small silver button, showing copper with S. Ph., while the borax glass appears bottle-green from iron. Argyrodite, from Freiberg, fuses less easily than the silver min- erals containing Sb" S" and As'S'j in closed tube, a lustrous black sublimate of mercury sulphide which, on cutting off the tube and heating with access of air, yields mercury (recognizable by gold foil). In open tube, sulphurous acid and a metallic mirror of mer- cury. On coal melts to a globule, first showing a faint white coat, sim- ilar to tellurous acid, but not coloring the flame; on longer blowing a lemon-yellow coat is deposited on this one, and finally a silver button remains. The yellow coat is neither from Pb nor Bi, and on longer blowing becomes ochre-yellow to brownish. A second more distant and faint grayish coat, consists of metallic mercury. (Th. Eichter.) COMPOUNDS OF SILVER WITH CHLORINE, BROMINE, AND IODINE. Chloride of silver {cerargyrite), on coal in 0. F. fuses very easily, emitting a pungent odor, to a globule, and in E. F. is gradually reduced to metal; immediately with soda. With oxide of copper on coal gives the chlorine reaction. Fused with bisulphate of potassa in a matrass, it forms a hyacinth-red bead, which is white when cold. If the salt is dissolved by warming it with water, and, the bead of chloride of silver dried and exposed to the sunlight, it soon assumes a gray or violet color. The other compounds of silver with the halogens behave quite similarly on coal. With oxide of copper on coal silver chloro-broraide tinges the 272 plattner's blowpipe analysis. flame greenish at first, but afterward intense blue; silver bromide colors first greenish, then greenish- blue; silver iodide, green. Fused with bisulphate of potassa in the matrass, they give dark red drops, which are all yellow when cold. Treated like the chlo- ride mentioned just above, and exposed to the sunlight, the chloro- bromide of silver bead is grayish-green to dirty green; the bromide of silver is dark asparagus-green; the iodide of silver remains yellow. According to Goldschmidt {Berg. u. Hiittenm. Zeit., 1876, No. 13) bismuth sulphide is of advantage in examining the above com- pounds. It is easily made by fusing together metallic bismuth and sulphur. A bit of the silver haloid, covered with a spoonful (Fig, 56) of powdered bismuth sulphide, is treated B. B. in a cavity on coal. Silver iodide gives a red coat (vide bismuth), silver bromide a yellow, and silver chloride a white one (iodide, bromide and chlo- ride of bismuth, respectively). Nearer to the assay a coat of bis- muth oxide and sulphate forms, often showing silver by its red color in spots. The test is yet better made in the open glass tube over the spirit flame. Here also a white bismuth sulphate coat forms, but this tends toward the bottom of the tube and can easily be distinguished from bismuth chloride, which is deposited in a circle around the tube. In this way chlorine and bromine can be at the same time detected, while on coal the bismuth sulphate coat is more easily confounded with that of bismuth chloride. c. Examination of metallurgical products. The method of examining the products above enumerated for silver may be deduced from the remarks under the examination for silver in general. 15. Platixuh, Pt; Palladium, Pd; Khodium, Rh; Iridium, Ir; PiUTHEXIUM, Eu ; AXD OSillUM, Os. Their occurrence in the mineral kingdom. They are found a. Metallic in the following minerals : Platinum, Pt, almost always combined with Fe, Cn, Rh, Ir, Pd, and Os, so that the amount of Pt is sometimes as low as 70 per cent. ; the amount of Fe is especially important, as it varies from 5.3 to almost 13 per cent. PLATINUM, PALLADIUM, RHODIUM, ETC. 273 Platiniridium, containing 27.8 Ir, 55.4 Pt, besides Eh, Pd, Fe and Cu; Iridium, 76.8 Ir, 19.6 Pt; also Cu and some Pb; Palladium, Pd, combined with small quantities of Pt and Ir; Palladium-gold.) ., ,, ■Di- J- i;i C'vi'ite gold; Rhodium-gold, ) Rhodium-gold, Iridosmine, lighi {osmiridium), — Ir, Os, with 46.7 Ir, 49.3 Os, and a little Eh, Eu, and Fe ; Iridosmine, dark, — Ir Os', with about 25 Ir, and Ir Os', with about 20 Ir; probably containing also Eu. Sperrylite, — Pt As", with 55.1 Pt, some Eh, and traces of Pe; Laurite, — probably (Eu, Os)" S'; Irite is said to be a mixture of osmiridium and chromite. Blowpipe characteristics of the above-mentioned minerals. Platinum and platiniridium are, B. B., infusible combinations of different metals, which cannot be so decomposed, by further treat- ment B. B., that the presence of each metal may be proved by a definite reaction. When tested with borax or S. Ph. they do not fuse, and are not oxidized or dissolved ; in this operation, if the mineral has been filed off in a fine powder, more or less colored beads, it is true, are obtained, but this color comes from the admixture of oxidizable metals, viz., iron and copper, which may be found in this manner. If the same compounds are fused on coal with borax and test lead, and a cupellation of the button commenced, the latter operation lasta • only so long as the infusible metals permit. There results finally an infusible combination, in which there is still much lead and which therefore possesses a lustreless surface and is somewhat brittle. If a medium-sized gold button is added and the cupellation performed with a stronger heat, a bright metallic button can be sometimes obtained, perfectly free from lead, and of a yellowish-white or even platinum-gray color. If it cannot be cupelled fine upon the cupel it must be treated on coal with vitrified boracic acid, as follows : a shallow cavity is bored in the cross section of a good coal, or in a charcoal capsule, the button containing lead laid in it, covered with a little vitrified boracic acid, and the whole treated with the point of the blue flame. When the button is fused the coal is inclined, so that the former comes out from under the melted glass, bnt still remains in contact with it, thus affording a large surface for oxida- tion. The point of the flame is now directed for a long time unia- 274 plattnek's blowpipe analysis. terruptedly upon the fluid glass, the metal being freely exposed to the air ; in this way all the lead is oxidized and dissolved in the boracic acid and the surface of the button becomes bright. The resulting alloy of gold, platinum, rhodium, iridium, palla- dium, and osmium (the iron and cOpper having been removed), is hammered thin, ignited on coal and dissolved in aqua regia, which leaves the finely di\'ided, black, metallic iridium behind. The solution is poured into a porcelain dish, treated with as much chloride of ammonium as is necessary to alter all the platinum into platin- chloride of ammonium, and the whole carefully evaporated to dry- ness at a gentle heat, in order to prevent any partial decomposition of the salts which have been formed. The dry salts are brought upon a filter and washed with alcohol of 60° to 70°, until no yellow color is imparted to fresh alcohol. By this operation the gold, with other soluble salts, is dissolved out, and after water has been added to the solution and the alcohol driven off by heating, can be pre- cipitated as metal from the warm solution by sulphate of iron. The residuary double salt is bright yellow and is altered to spongy plat- inum by heating to redness in a platinum spoon. In such small assays no notice can be taken of the minute quantities of Eh, Pd, and Os, which are present in the native platinum. The metallic precipitate of gold can be fused on coal, with the addition of a little borax or S. Ph., to a button, which is generally quite pure. If, however, it does not appear perfectly pure, it is fused on coal in E. F. with some borax and three parts of pure silver, the alloy treated first with nitric acid, and then the residuary gold, after washing, with bisulphate of potassa, as will be described in detail under the quantitative gold assay, for gold containing rhodium. In this way all the metals that might be present are entirely separated from the gold, and if this, when well boiled with water, is melted on coal to a button, it will appear perfectly pure. Palladium.— The behavior B. B. of this native metal is not known. Palladium which has been reduced from the oxide, but has not yet been hammered, behaves, according to Berzelius, as follows: Carefully heated on platinum foil to low redness, it acquires upon the surface a blue color, which, however, disappears at full redness. On coal alone, it is infusible and unchangeable. With sulphur in E. P., it fuses, but in 0. F. the sulphur burns off, leaving the palla- dium behind. When fused with bisulphate of potassa in a sufli- ciently large matrass, it is dissolved witli the evolution of sulphurous vjid. The salt appears yellow when cool. Iridosmine, light-colored, is infusible B. B. Fused in a matrass GOLD. 275 ■with nitre, vapors of osmic acid are evolved, which can be verj ■distinctly recognized by their unpleasant odor. Iridosmine, dark-colored, is infusible B. B., but gives an odor of osmium ; it is, according to G. Eose, also distinguished from the former by the fact that it loses its lusti's in the blowpipe flame, becomes dark colored, and yields, even in the flame of a spirit-lamp, the reaction of osmium, viz. : that the flame is rendered luminous, as if from the burning of defiant gas. Fused with nitre, it yields more fumes of osmic acid than the former. Laurite decrepitates violently, and is infusible B. B,, but smells strongly of sulphurous acid, and later of osmic. Not attacked by aqua regia or bisulphate of potassa, but dissolves on fusion with caustic potash and nitre with a greenish color. When cold the mass is brown and dissolves in water with an orange-yellow color. 16. Gold, Au. Its occurrence in the mineral kingdom and in metallurgical products. Gold is almost always found in nature in the metallic state, but is never pure, being combined in every case with other metals in the following minerals : a. With silver in Ifati ve gold, a combination of Au and Ag in indefinite and varying pro- portions, 80 that it contains from 0.16 to almost 40 per cent Ag (electriim), a little Cu and Fe also sometimes present. b. In combination with mercury in andl61), for the decomposition of wohlerite and eudialyte, which can be decom- posed by hydrochloric acid. Should the compound not be decomposed by hydrochloric acid, it must be fused with soda and borax, p. 94, the fused mass evapo- rated to dryness with hydrochloric acid, and then treated with water. The residue of acids is then to be washed with acidulated water on a filter, dried and fused with five volumes of carbonate of potassa, as before ; the beads are pulverized and further treated, as above. 284 plattner's blowpipe analysis. The reactions for the acids in question are in no way injured by tke presence of the silicic acid. 19. Antimomtt, Sb. Its occurrence in the mineral kingdom and in metallurgical products. This metal is found in nature — a. In the metallic state, alone, in Native antimony,— Sb, usually containing Ag, Fe, and As. b. In combination with other metals, in Breithauptite, vide nickel ; Allemontite {arsenical antimony), — Sb As', with 34.8 Sb ; a variety from the Palmbaum mine, near Marienberg, gives the formula Sb As", with 8 Sb; one from California, 9.18 Sb. DvBcrasite, vide silver. c. In combination with sulphur, alone and also with other metallic sulphides, in Stibnite, {gray antimony,) — Sb' S' with 71.7 Sb; Berthierite, probably Fe S, Sb' S', with 57 Sb; often with Mn; UUmannite, vide nickel; Bournonite, zinkenite, plagionite, jamesonite, meneghinite, feather- ore, boulangerite, geocronite, kilbrickenite, steinmannite, ko- bellite, and clayite, vide lead ; Chalcostibite, tetrahedrite, vide copper; Stephanite, polybasite, pyrargyrite, pyrostilpnite, miargyrite, freies- lebenite, brongniardite, freibergite, vide silver. d. In a combination of sulphide and oxide of antimony, in Kermesite (red antimony),— 2 Sb' S' + Sb' 0', with 75.3 Sb. e. In the oxidized state in Valentinite and senarmontite, — Sb' 0', with 83.5 Sb; Cervantite, — Sb' 0', Sb' 0', with 79.2 Sb; stibiconite {antimony ochre, pt.) Sb' 0', Sb' 0' + 2 H' 0, with 74.6 Sb. /. In combination with earths and metallic oxides in Eomeite, vide lime, and in Bindheimite, vide lead. In metallurgical products antimony only forms an essential ingre- dient in the sulphide of antimony, as extracted by liquation; as a EXAMINATION' FOR ANTIMONY. 285 secondary constituent it is found in several products from lead and silver smelting, when the smelted or amalgamated ores were stibif- erons silver or lead ores, or were not free from an admixture of etibnite. Here are to be specially mentioned : Raw lead and lead reduced from abstrich, vide lead ; Retort-silver, vide silver; Raw matt, lead matt, copper matt, furnace crust, vide iron, in which products the antimony is present as Sb^ S', also abzug and abstrich, vide lead, which products contain the antimony as antimonic acid Sb" 0', combined with oxide of lead. Besides these products, there are several others, which sometimes contain small quantities of antimony, as certain kinds of black copper and speiss, and the litharge that is obtained from the cupel- lation of lead containing antimony. Examination for Antimony, Including the blowpipe characteristics of the minerals belonging here. a. General examination, for antimony. The examination for antimony is very simple, and is often limited to a test of the substance on coal or in an open tube. Alloys are generally tested on coal and the antimony recognized by the coat, which it deposits, vide behavior of antimony on coal, p. 67 If the antimony is combined with metals which also give a coating on coal, a coating of oxide of antimony is formed, it is true, that ia visible when the amount of antimony is not too small, but the usually less volatile coating, that is at the same time formed by the other metals, appears sometimes changed in color, as is the case with lead that contains antimony, p. 322. If, however, such a combina- tion is treated with a little vitrified boracic acid, so that the fused glass is covered with the blue flame, the metallic button remaining on the side of the glass, the lead is dissolved by the boracic acid as oxide and a coating of pure oxide of antimony is formed, if too much heat is not applied. The method is the same for bismuth. If the antimony is combined in small amounts with metals, such as copper, from which it can only be separated with difficulty, no coating is formed by a slow volatilization ; such an alloy is treated on coal in 0. F, with S. Ph., until a part of the antimony has been 286 plattner's blowpipe axaltsis. oxidized and taken np hy the glass, which is then separated from the metallic button and treated in E. P. on another part of the coal with tin. It is then observed whether, upon cooling, it assumes an opaque, dark-gray or black color from which the presence of antimony may, in most cases, be distinctly recognized, p. 86. Since, however, a portion of the metals combined with the antimony, if they are oxi- dizable, are also oxidized and taken up by the glass, it must be con- sidered what colors these oxides impart to the glass when treated with tin. Especial regard must be paid to this point when bismuth is present, for its oxide behaves in S. Ph. almost the same as the oxides of antimony, pp. 81 and 86. If therefore both metals are present together, combined with a third metal, the examination in S. Ph. is not decisive ; in this case a larger assay piece must be used and the point decided by examining the coatings very carefully,* or the wet way mu^t be resorted to. In the latter case the alloy is dis- solved in aqua regia, the solution mix6> i<« a matrass a small piece of pure siderite ; pulverize, when cool, the proto-sesquioxide of iron thus formed, add it to the assay, and heat the whole to boiling ; by this means, hU the manganic acid if reduced and separated from the solution. EXAMIKATIOSr FOR CHKOMIUM. 29^ the yellow color of the former rendered proportionably paler, accord- ing to the amount of the latter present. With phosphoric acid the behavior is the same. These admixtures, however, do not affect the reaction of the chromium, when the resulting precipitate is tested with borax or S. Ph. Silicates which contain only little chromium, but much iron or other coloring oxides of metals, and which only give with the fluxes the colors of iron or the other oxides, can not be examined for chromium exactly according to the method just described, as silicates are not decomposed by nitre. It is therefore necessary to choose another method, by which the otlier constituents can be found at the same time. The pulverized mineral is fused on coal in 0. F. with one to one and-a-half times its volume of soda, and one-half to three-fourths parts of borax, to a clear bead; this is puhevwed and evaporated to dryness with hydrochloric acid. The chlorides thus formed are dissolved in water, the silica filtered off, the protochloride of iron in the solution changed to sesquichlo- ride by boiling with a few drops of nitric acid, and the bases, viz., sesquioxide of chromium, iron, alumina, etc., precipitated by am- monia from the acid solution. The precipitate is collected on a filter, washed, and fused with soda and nitre, as above. By this means chromates of the alkalies are formed, which can be decom- posed by acetic acid and acetate of lead, as described above. Spinel is fused on coal in 0. P. with two parts by volume of soda, and three parts borax, to a bead, the latter pulverized, mixed with an equal amount of nitre, and fused in a platinum spoon. The mass is now dissolved in water, and the solution acidified with acetic acid, and tested with acetate of lead to ascertain whether the spinel in question contains chromium or not. If a precipitate is formed it must be tested with borax. b. Blowpipe characteristics of the minerals belonging here. Berzelius has examined B. B. various chrome ochres, from differ- ent localities. They lose color when heated, and become almost white, but do not fuse. The sesquioxide of chromium is dissolved in borax and gives the glass a fine green color. The piece becomes white and dissolves with difficulty. In S. Ph. they behave similarly. Are dissolved in soda with difficulty, and require a large amount of the flux. The glass, even when fused, is not transparent, and appears, when cool, like a dirty, grayish-green enamel. 300 plattner's blowpipe axalysis, Wokhonshoite yields water and changes its green color to brownish in the matrass. In the forceps, shows upon the edges traces of melting, but does not fuse, cracks upon the surface, and becomes brown. Borax and S. Ph. dissolve it imperfectly, giving the chromium colors. The insoluble portion is black. With soda on coal it fuses with effervescence to a globule, which when cool appears green and yellow in spots. On platinum foil gives chromate of soda, which is fluid, and an undissolved, dark-red mass. Kdinmereritc in a matrass gives water and becomes grayish- white. In the forceps fuses only on the extreme edges to a yellow enamel. In borax it dissolves entirely, but leaves in S. Ph. a silica skele- ton, coloring the beads emerald-green. With soda fuses to an opaque, yellow mass. Ouvarovite {chrome garnet), from Bisersk in Siberia, gives water in a matrass, according to Berzelius, and becomes opaque and dirty yellow ; turns green again, however, when cool. In the forceps is infusible, but appears darker and brownish on the edges, where the heat was the strongest. In borax is dissolved very slowly indeed, giving an emerald- green glass. In S. Ph. also very slowly dissolved. The glass shows the usual colors of chromium ; transparent red when hot, then opaque, and when perfectly cool, clear emerald-green. With soda on coal forms. a greenish-yellow slag. On platinum foil the fluid soda is colored yellow by the chromium. , 24. Aksekic, As. Its occurrence in the mineral kingdom and in metallurgical products. Arsenic is not very rare; it is found under various conditions, viz.: a. Metallic and alone in Native arsenic, — As, sometimes containing a little Fe, Co, Ni, Sb, and Ag ; Arsenical bismuth {Arsenglanz), consisting, according to Kersten, of 97 As and 3 Bi; in another variety Frenzel found chiefly As, with a little Sb, Fe, Ni and S. In combination with other metals, viz. : manganese, iron, cobalt, nickel, copper, and antimony {rj. v.). EXAMINATION' FOE AESBNIC. 301 b. Combined with sulphur in Kealgar, — As S, with 70.1 As; -Orpiment,— As' S', with 61 As. In combination with sulphur and other metallic sulphides, includ- ing several of the minerals enumerated under iron, cobalt, nickel, copper, silver, and antimony. Lorandite,— Tl As S\ c. As aisenous acid in Arsenolite, — As" 0", with 75.8 As; daudetite has the same composi- tion. d. As arsenic acid in combination with bases, viz. : lime, oxide of iron, protoxides of cobalt and nickel, and oxides' of lead and copper iq.v.). Since many arsenical ores and minerals are worked on the large Hcale, either alone, or with other ores, for the metals they contain, ■and since arsenic can only be separated with great diflSculty from certain metals by roasting, it in consequence not only forms a chief constituent of the actual arsenical products, viz. : metallic arsenic, realgar, orpiment, and white arsenic, but is also a frequent ingredient •of certain other products, which are to be further treated. The latter embrace especially the products already mentioned =nnder iron, cobalt, nickel, lead, tin, copper, silver, and gold, viz. : Rohstein, lead and copper matts, cadmia, abzug, abstrich, and lead, vobalt and nickel speisses. Examination for Arsenic, Including the blowpipe characteristics of the minerals belonging here. In addition to its volatility when heated on coal, arsenic has the peculiarity of diffusing a striking, garlic odor, and coating the coal with arsenous acid, p. 67; it may also be sublimed unaltered in the closed tube, collecting in a crystalline form on the glass, through which it shows a metallic lustre, p. 62. The acids of arsenic can be very easily reduced to metal and recognized as such, as will be seen from the methods described below; arsenous acid is also volatile, p. 64. Native arsenic sublimes in the closed tube, sometimes leaving a fixed metallic mass, which with fluxes on coal often shows iron, cobalt, or nickel. Another portion of this mass fused on coal with enough test lead and borax in E. F. and then cupelled on bone-ash, frequently leaves a silver button. On coal behaves like pure arsenic, p. 67, but frequently leaves a 302 plattnee's blowpipe analysis. Blight residue of arsenic combined with Fe, Co, Ni, and often cou taining a little Ag. Arsenical bismuth from the Palmbaum mine, near Marienberg^ Saxony, yields at first in the closed tube sulphide of arsenic, then metallic arsenic, and leaves a trifling, dark-gray residue, showing with the fluxes iron, cobalt, and bismuth. Gently heated in the open tube evolves sulphurous and arsenous acids, more strongly heated yields first a little sulphide of arsenic and then metallic arsenic. Kindled B. B. on coal it continues to bum of itself, giving off gray arsenical fumes and becoming sur- rounded with crystalline arsenous acid. COMPOUIIDS OF AESENIC WITH OTHEE METALS. Some of these yield a sublimate of metallic arsenic in the closed tube ; others do not, vide arsenides under iron, cobalt, nickel, and copper. Occasionally a little arsenous acid is formed by the inclosed air. In the open tube they all yield arsenous acid, mingled with oxide of antimony in case the compounds contain antimony. The powder will yield a sublimate when a fragment of the substance fails to do so. Most of the metallic arsenides treated on coal in R. V. yield part of their arsenic, which volatilizes and forms a coat of arsenous acid. If there is a considerable proportion of arsenic present the assay evolves copious, grayish-white fumes, which produce the garlic odor of the suboxide, and thus at once show the presence of arsenic ; but if the amount is trifling the fumes are not always perceived, and the odor seldom during the blast. In this case the glowing assay should be held under the nose, in order that the odor of the small quantities of escaping arsenic may be perceived. When but little arsenic is combined with metals from which it is separated with difiiculty, as cobalt and nickel, the compound may be fused in 0. F. with test lead on coal, and the presence of volatilizing arsenic ascertained by the odor. Should none of the preceding methods suflSce to detect a little arsenic combined with a metal, or in a metallic compound, the fol- lowing process will serve to detect it. Brittle metals and metallic compounds which can be pulverized are reduced to powder, or if malleable they are reduced by filing, and about fifty to seventy-five milligr. are then mingled in the agate mortar with five to six volumes of nitre and ignited in the platinum spoon, according to p. 97, with the aid of the blowpipe flame, until no more metallic particles are visible. The metals oxidize and arsenic acid is formed, which combines with the potassa. ARSENIC — WlXn OTHER JfETALS. 303 The mass in the spoon is now digested with water over the lamp- flame in a porcelain dish, until everything is removed from tlie Bpoon, after which two separate methods may be employed. By the first the clear solution is poured off from the oxides into a little porcelain vessel, p. 43, acidified with hydrochloric acid, thirty to fifty milligr. of sulphate of magnesia dissolved in it with the aid of heat, an excess of ammonia added, and the whole heated to boil- ing. Arsenate of ammonia and magnesia separates and settles quickly when the vessel is removed from the flame. The quite clear fluid is decanted from the precipitate, which is washed by boiling it with strongly ammoniacal water, again allowed to Settle, and freed by decantation from the fluid, after which it is immediately dried in the vessel. The dry salt is mixed in the mortar with three volumes of neutral oxalate of potassa, or, according to Fresenius and von Babo, with six volumes of a mixture of cyanide of potassium and soda in equal parts, and then treated on coal, or in a matrass with a narrow neck. In the former case it is fused in the E. F. and the volatilized arsenic detected by the odor ; in the latter case it is at first moderately warmed over the spirit-lamp in the matrass to expel any traces of moisture, which are collected by an inserted roll of blotting-paper, after which the mixture is heated to fusion. The arsenic acid is reduced and forms a sublimate of metallic arsenic in the neck of the matrass at a, Fig. 75. Should the amount of arsenic be too small to produce a dis- tinct mirror, it is only necessary to cut off the neck just above the sublimate with a file and then to hold the portion of the matrass on -which the sublimate is situated in the flame. If the subli- mate consists of arsenic it will volatilize and yield the arsenic odor. The second method consists in decanting the solution of arsenate, nitrite, and nitrate of potassa from the residue into a test tube, adding a few drops of sulphide of ammonium and agitating the whole, after which the resulting sulphide of arsenic is precipitated with dilute hydrochloric acid. The fluid is boiled to facilitate the separation of the precipitate, which is filtered out, thoroughly dried, and triturated in the mortar with four to five parts of dry, neutral oxalate of potassa and some charcoal dust, or with a mixture of cyanide of potassium and soda, and then heated to redness in a not too narrow glass tube, closed at one end, or better still, in a narrow- necked matrass. Fig. 75. Sulphide of potassium and metallic arsenic are produced and the ; 304 plattk'ek's blowpipe ai^altsis. latter forms a sublimate, which may be recognized by its lustre and crystalline character, or if only in trifling quantity may be volatil- ized and detected as above. It is very essential in such reduction assays that the mixture to be treated shall be as free from water as possible, and therefore both the substance and the reducing agent should be thoroughly dried. S0LPHIEE OF AESEiflC. Realgar and orpiment treated in the matrass fuse, boil and are sublimed ; the former yields a sublimate red when cold ; the latter a dark yellow, and both sublimates are transparent. Gently heated in the open tube they burn and yield sulphurous and arsenous acids. Too strongly heated a part of the assay is liable to sublime unchanged. On coal they burn with a whitish-yellow flame and grayish-white fumes. To separate metallic arsenic from the sulphide, or from sulphur containing arsenic, proceed as directed on page 303. When the amount of arsenic appears very trifling in comparison with the sulphur, it is as well to remove the excess of the latter by subliming it at a gentle heat in a matrass, and then to break up the matrass and treat the pulverized residue by reduction in a narrow- necked matrass. According to Berzelius the arsenic can be oxidized by heating the open tube just above the assay, so that the ascending fumes may be entirely oxidized. The tube is then drawn out directly with the collected arsenous acid and reduced according to p. 305. Lorandite melts very easily in the closed tube, giving a sublimate, black near the assay, red farther away, and orange-red where most volatile. The first two contain Tl. In the open tube yields S 0% volatile, white As' 0', and a sublimate of thallium sulphate on the bottom of the tube, which disappears B. B. On coal fuses easily, giving an intense green flame, and two coats : one, As^ 0'; the other, less volatile, a thallium coat, giving a green flame coloration. SULPHO-ARSEXIDES. The other natural sulpho-arsenides yield in the closed tube, ac- cording to their composition, partly a little sulphide of arsenic with much metallic arsenic, partly sulphide of arsenic alone, while part yield no sublimate whatever. In the open tube they all yield arsen- ous and sulphurous acids. The metallurgical products containing AESENIC— AESENOLITE. 305 compound sulphides and arsenides in not too small quantity show the same behavior. On coal in R. F. they frequently emit a distinct arsenical odor, but sometimes a small quantity of arsenic cannot always be thus per- ceived,, since it either volatilizes in combination with arsenic, or in .he presence of cobalt or nickel is not volatilized at all. Such sub- stances, including chiefly many metallurgical products, viz. : Eoh- stein, lead matt, cadmia, etc., may be powdered, mixed with three to four parts of neutral oxalate of potassa, or cyanide of potassium, and fused on coal in E. P. Sulphur is thus separated as sulphide of potassium, and the arsenic, if not combined with cobalt or nickel, volatilizes with its peculiar odor. When this method yields no satisfactory result a certain one may be obtained by the process for metallic compounds containing little arsenic, p. 303, et seq. AESENOLITB (AESENOUS ACID). In the matrass sublimes very readily, and the crystalline subli- mate often shows distinct octahedra under the magnifier. Accord- ing to Berzelius very trifling quantities of arsenous acid may be reduced to metal by using a glass tube drawn out to the diameter of a coarse knitting-needle and sealed at the narrow end. The arsen- ous acid, which may amount to less than one milligr., is placed in the drawn-out part at a, Rg. 76, and over it is inserted a splin- ter of charcoal reaching from c to b. The nan-ow part, cb, is ^'s- ''^■ then heated in the spirit-lamp, until the charcoal glows, when the end containing the acid is likewise drawn into the flame. The vapor of arsenous acid passing over the glowing coal is reduced and a metallic coat of arsenic forms in the colder part at d. Should the amount of arsenous acid be very trifling indeed, only a black film of arsenic will be produced between c and d, but by gradually bringing the flame nearer and nearer to this it may be driven together to a ring, and if the tube is cut off at c and the portion d held in th» flame the arsenic will be volatilized and afibrd its characteristic odor. Heated alone on coal arsenous acid volatilizes without diffusing any odoi% but when mixed with moist oxalate of potassa and treated in R. F. it is reduced to metallic arsenic, which volatilizes and afibrda the arsenic odor. Oxide of antimony (antimonous acid), destined for medicinal and 306 PLATT2fER'S BLOWPIPE ANALYSIS. pharmaceutical purposes, must be tested for arsenous acid, and if not much less than a thousandth part is present it will afford a dis- tinct arsenical odor, when the oxide of antimony is treated on coal in R. F. with neutral oxalate of potassa or cyanide of potassium. Should this test give no decisire result, a reduction assay must be made in the matrass, with oxalate of potassa, or a mixture of cyanide of potassium and soda. Oxide of antimony containing less than a thousandth part of arsenous acid, when heated to redness in a nar- row-necked matrass with three volumes of the neutral oxalate and one of charcoal dust, will afford a very distinct metallic mirror, which on further treatment in the spirit flame is volatilized with an unmistakable arsenic odor. ARSENIC ACID. Strongly ignited in the matrass it is converted into arsenous acid, which sublimes, and oxygen which escapes. On coal it is reduced to metal, which volatilizes immediately and diffuses a strong arsenic odor. COMPOUNDS OF THE ACIDS OF ARSENIC WITH EARTHS AND METALLIC OXIDES. These compounds may be tested for arsenic in various ways. A few arsenates can be recognized by the crystalline arsenous acid which they yield in the matrass, vide arsenates of iron, cobalt, and nickel. The greater number are, however, recognized by the light- blue color which they impart to the flame when tested in the forceps, provided the bases themselves do not color the flame intensely, p. 77. When the presence of arsenic or arsenous acids cannot be detected by testing the salts alone, proper reagents must be em- ployed. A very simple method of recognizing arsenates consists in mixing the powder with soda, or better still, with neutral oxalate of potassa, or cyanide of potassium, and treating it in R. F. on coal, when the odor will show whether metallic ai'senic is liberated or not. This test 18 not, however, suflBciently decisive in all cases, especially when the acids of arsenic are combined in trifling quantity with metallic oxides, which are easily reduced and then form fusible compounds with the arsenic, from which the latter can only be separated with diflBculty. Unless much arsenic were present it might happen that none of it would then be liberated. In such cases the proceia described for detecting small quantities of arsenic in metallic TELLURIUM. 307 compoundSj p. 303, is tollowed, but in place of the nitre a mixture of €qual parts of nitre and soda is used for the fusion. Arsenates and arsenites of bases which are reduced with difi&culty, or when easily reducible have no great affinity for arsenic, can be tested by mixing the fin6 powder with three to four volumes of neutral oxalate of potassa, or a mixture of cyanide of potassium and soda, and fusing it in a matrass. Eegard must be had to all tliat has been said on p. 303. Quite distinct mirrors are obtained from salts of the earths, or oxide of silver ; somewhat less distinct mirrors from salts of iron or copper. 35. Tellurium, Te. Its occurrence in the mineral kingdom. Tellurium usually occurs in the metallic state : a. Alone in ITative tellurium, Te, which is seldom free from other metals, as gold and iron. I. Combined with other metals: Aitaite, lude lead; Tetradyinite, vide bismuth ; Hessite, vide silver ; Sylvanite, oalaverite, petzite, krennerite, nagyagite, and weisstellur, vide gold. Tellurite {tellnroits acid), — Te 0^, accompanies native tellurium occasionally. Montanite, vide bismuth. Examination for Tellurium. Native tellurium in the open tube fuseb. burns with a bluish- igreen flame, and emits fumes. The fumes collect within the tube to a grayish-white sublimate, which when strongly heated is con- verted entirely into tellurous acid and fuses to clear, transparent ^rops. On coal it behaves as stated on p. 67, but the volatilizing tellurium generally leaves a slight residue, which treated with borax and a little test lead in R. F. imparts an iron color to the glass, and the lead yields by cupellation a small gold button. The dark colors sometimes shown by the sublimates in open tube and on coal result from volatilized tellurium. Compound substances may be tested for tellurium both in the open tube and on coal. The bbhavior of the above-named com- pounds of tellurium with other metals in the open tube is given in the corresponding places, but it may be generally remarked that in roasting a mineral containing tellurium in the open tube, the latter 308 plattner's blowpipk analysis. Tolatilizes more or less completely, is changed to tellurous acid and forms white fumes, which condense rather near the assay. On heat- ing the tube where the coat is thickest with the blowpipe flame, the acid fuses to clear, colorless drops, most distinctly perceived with the magnifier. It should not be heated too strongly or too long, however, as tellurous acid does not withstand the heat under access of air. Should much lead be present a gray sublimate forms near the assay and a white one further from it. The latter fuses to color- less drops with a moderate heat and therefore consists of tellurous acid, while the gray sublimate does not fuse to drops, but is altered to a half-fused, grayish film on the glass. According to Berzelius, it is tellurate of lead. When bismuth is present it remains behind, and the tellurium sublimes as tellurous acid. On continued heating the remaining metal oxidizes on the surface, and is surrounded by fusing, brown oxide of bismuth. In many cases the examination for tellurium may also be advan- tageously conducted in the closed tube. It is well known that tel- lurium in combination with potassium or sodium forms a purple Bolution in boiling-hot water, and thus its presence can be detected. According to Berzelius, it is therefore only necessary to triturate the substance with soda and some charcoal, fuse the mixture in the closed tube, and after it is cold to drop a little boiling water into the tube. After a time this assumes a more or less intense purple color, from the dissolved telluride of sodium. This test is applicable no*- only to substances containing metallic tellurium, but also to the acids of tellurium, which are thus reduced. According to von Kobell, the natural tellurium compounds when gently heated in a matrass with much concentrated sulphuric acid, impart to it a purple or hyacinth-red color, whicli disappears on adding water, while a blackish-gray precipitate is formed.* When a mineral containing tellurium is treated on coal it generally yields. a white, tellurous acid coat, with a brownish or blackish border, disappearing under the E. F., with a bluish-green tinge, p. 67. .Should the horse-radish odor be also perceived this is a certain indication of selenium. If the mineral contains lead or bismuth and is treated alone on coal for only a few moment^, no pure tellurous acid coat is obtained, * The color disappears quickly if the tellurides contain much sulphur. Artificial tellurium compounds give the same reaction. EXAMIKATION BOE WATEE. 309 but a mixture of this with oxide of lead or bismuth is liable to be deposited. This difficulty can be remedied by mixing the powdered assay with an equal volume of vitrified boracic acid and treating it in E. F. The oxide of lead or bismuth is dissolved in the boracic acid, notwithstanding the reducing flame, and yields no coat, while the tellurium alone volatilizes and coats the coal. When much Belenium is also present a portion of it is deposited on the coal, and then the tellurou^ acid coat is less distinct. In such cases the mineral must also be tested in the open tube. C. Examiuatiou for Non-Metallic Elements and Acids. 1. OXYGEK, 0, AND HtDEOGEN, H, IN COMBINATION AS Watee,— H' 0. Occurrence of water in the mineral kingdom. It forms an essential constituent of most natural salts, many sili- cates, and the natural hydrates, but also occurs only as an accidental ingredient of many minerals, as shown by their respective chemical composition, already given in various places. Examination for Water. This is performed very simply in a matrass, p. 32, Fig. 36, A, which has been freed from moist air by warming and drying it, p. 23, after which it is gradually heated in the spirit flame. If the substance contains mechanically combined water, or is a salt which contains chemically combined water and is itself soluble in water the combined water will, in the former case be entirely vaporized by the first action of the heat, and in the latter case partly. The vapor condenses in the narrow, cold part of the neck to drops, which are plainly visible. A substance which is not soluble in water seldom yields its chemically combined water at first, but when the matrass is heated to redness the water escapes and condenses as before. To obtain a distinct water reaction from silicates containing little water they must be powdered, and, if necessary, heated with the blowpipe. Some phenomena which may occur while testing for water have been especially noticed on pp. 60 and 61. When there is very little water a narrow closed tube is often better than a matrass. 310 PLATTS^EK'S blowpipe AN'ALTSIS, 2. KlTEOGEU", N, AND OxTGEN, 0, COMBIXED AS NlTRIC Acid,— N' 0'. This acid occurs with potassa ia nitre, vide potassa; with soda in toda nitre, vide soda ; and with lime in nicrocalcite, vide lime. Examination for Nitric Acid, hicluding the blowpipe characteristics of nitrates in general. Xitrates, part of which fuse in the matrass when heated, are thereby decomposed more or less readily. When the acid is com- bined with strong bases, oxygen alone is at first liberated, but in so small quantities that it cannot be recognized by means of a glowing splinter; nitrites remain, which are perfectly decomposed only by a very strong heat. Isitrate of ammonia fuses very easily and ia decomposed, with ebullition, into water, and protoxide of nitrogen ; if heated too quickly or strongly, or in a matrass with a narrow neck, an explosion is liable to occur. Salts with weaker bases evolve at a moderate heat oxygen and nitrous acid, the latter being recog- nized by its yellow color and its odor. When nitrates of the fixed alkalies, or alkaline earths, are so strongly heated on coal, that the coal in contact with them glows, they deflagrate violently and are converted into carbonates. Other nitrates deflagrate less vividly and leare their bases as eartlis, metal- lic oxides, or, in case the latter are easily reduced, as metals, which if volatile pass off partly or entirely in fumes, and coat the coal. A small amount of a nitrate present in another salt or substance can be readily detected, by heating it with rather more than its volume of bisulphate of potassa in the closed tube or matrass. The tube is then fiUed with gaseous nitrous acid, the yellow color of which may be most clearly seen by looking down through the tube. Nitre, soda nitre, and nitrocalcite are immediately recognized as nitrates by the above tests, and their bases may be distinguished by the color they impart to the flame. CARBON AND CARBONIC ACID. 3H 3. Carbon, C, and Carbonic Acid, CO'. Occurrence of carbon and carbonic acid in the mineral kingdom and in metallurgical products. Carbon occurs in nature a. Alone in Diamond, C ; Anthracite, C, with a little H, and N ; it leaves on combustion more or less ash, consisting of Si 0", AI' 0' and Fe' 0' ; Graphite, C, usually containing Fe, Si 0', Ca 0, AP 0' and H' ; sometimes also Cr ; Blaek-band consists essentially of Fe C C, with varying quantities of Mn C 0', bituminous coal, elay, H" 0, Fe" 0', etc. Pyrortiiite, vide cerium ; I. Combined with hydrogen in Idrialite, — C'H", with cinnabar and earthy substances in hepatic einno6ar from Idria ; Koenlite,— C H ; I'iohtelite, tecoretin, hartite, branchite, compounds corresponding more or less closely to C=H^; Petroleum {naphtha, mineral oil),— C and H in varying proportions; Ozocerite, paraffin, hatchettite, neft-gil, probably C H" ; Seheererite,— H' ; Elaterite, essentially C H^. c. Combined with hydrogen and oxygen in Asphaltum, — C, H, 0, in varying proportions ; Ketinite (Erdharz), which name is used to designate in general the mineral resins of brown coal; here may be included krantzite, — C'°H"0; walchowite, — Qi! jjiB ; pyroretin, of similar composition ; Tasmanite and trinkerite are similar compounds containing also sulphur ; Dopplerite, — C H'"©', an organic substance from the peat of Aussee. Amber {succinite), — C'°H"0 ; amber consists of succinic acid, an ethereal oil, two resins, soluble "ui alcohol and ether, and an insoluble substance, which forms the chief constituent ; Bituminous coal, — C, H, 0, in variable proportions, with carbon predominating (74 to 96 per cent.) ; oxygen = 3 to 20 per cent.; hydrogen = 0.5 to 5.5 per cent., and very little nitrogen : furthel impurities (1 to 30 per cent.) arising from earths, metallic oxidea and sulphides, especially iron pyrites ; Brown coal and lignite ; composition similar to the preceding, but more oxygen and nitrogen ; 313 plattner's blowpipe analysis. d. Combined with oxygen as carbonic acid. Carbonic acid is found in nature, both as a free gas, and combined with bases in many minerals, which have already been enumerakd. Small quantities of carbon are likewise disseminated throughout several minerals, either free, or combined with hydrogen, oxygen, or nitrogen. In metallurgical products carbon forms an essential constituent of raw iron and steel, while other products, especially iron hears, frequently contain a little carbon, vide iron. Examination for Carbon and Ccu-bonic Acid, Including the blowpipe characteristics of the minerals bebngtng here. Diamond. — According to Petzholdt a small diamond placed on platinum foil is entirely consumed by directing the blowpipe flame upon it from below, while toward the end it glows brightly. The product of combustion is carbonic acid gas. Anthracite usually yields in the matrass moisture, but no empy- reumatic oil; it is not combustible in the candle-flame. Heated in th€ platinum spoon with the 0. F. it bums very slowly, without flame, and leaves an ash, containing more or less iron. Graphite sometimes yields considerable water. Heated over the Bpirit-lamp in the platinum spoon it is unaltered ; in the forceps in O. F. it gradually decreases in volume. The streak produced by it on fire-clay and ignited in the 0. F., until all the carbon is gone, frequently becomes red from oxide of iron. The powder heated to redness with nitre in the platinum spoon deflagrates, and after wash- ing away the salt, now chiefly altered to carbonate of potassa, earthy, and metallic admixtures remain, which may be further tested as for eilicates, p. 128. Blach band from "Westphalia yields water, and a feebly bituminous odor in the matrass. B. B. on coal, bums reddish-brown. Acida Lberate carbonic acid ; when boiled with aqua regia it finally leaves only ooal and a trace of silica. Ecenlite fuses at 114° C. and is decomposed with ebullition at 200°. It leaves a coaly residue. Ozocerite fuses in the candle-flame to a clear, oily fluid, which solidifies on cooling. At a higher heat it bums with a flame and volatilizes, sometimes leaving a slight coaly residue. EXAMIITATIOlir FOR CAEBON AND CAEBOIfIC ACID. 313 Scheererite, according to Stromeyer, fuses at 45° C. to a colorlesr fluid, which on cooling forms a radiated mass. Above 100° it vola- tilizes and ct)ndenses in acicular crystals. It burns completely with a somewhat sooty flame and slight odor. Asphaltum fuses very easily in the matrass, evolving an empyreu- matic oil, a little ammoniacal water, and combustible gases, and leaving a coaly residue, which yields by combustion on a clay capsule an ash, consisting chiefly of silica, alumina, and sesquioxide of iron. It burns with a bright flame and much smoke. Retinite from Halle fuses in the matrass, blackens, and yields a brown, thick oil and acid water. It burns with a bright flame and much smoke. Amber fuses with some difficulty in the matrass, yields water, empyreumatic oil, succinic acid, and gases, and leaves amber resia (Bernsteincolophonium). It burns with a bright flame and a peculiar agreeable odor. Bituminous coal heated in the matrass is infusible, close-burning coal; 0^ sinters together, open-burning coal; or becomes soft and swells up, caking coal. It evolves in all cases empyreumatic pro- ducts and combustible gases, often including sulphuretted hydrogen. The residue is coke, having a more or less metallic lustre, which takes fire with difficulty in the air and behaves like anthracite. Held in the candle-flame, or heated B. B. on the clay capsule, it burns with a luminous, smoky flame, and when all the coal is con- sumed leaves an aSh, consisting of silica, alumina, lime (gypsum), and sesquioxide of iron. Brown coal is infusible in the matrass, but some varieties are somewhat softened ; on further heating they evolve combustible gases, acid water, empyreumatic oils, and a peculiar, disagreeable odor. There is a large residue, which tested in the open air behaves like coal, and often leaves a considerable ash. It burns in the candle-flame, or on the clay capsule, with a smoky flame and disagreeable odor. According to von Kobell bituminous coals and asphaltum boiled with potassa lye, impart to it only a feeble, yellowish color, or none at all. Asphaltum is also much more fusible than the most fusible bituminous coals, and melts in drops in the candle-flame. The brown coals, with few exceptions, impart to boiling potassa lye a brown color. The bituminous coals ignited in the candle- flame, or before the blowpipe, are immediately extinguished when removed from the flame, but the brown coals continue to glow for some time. 314 PLATTIfER'S BLOWPIPE AXALVSIS. In minerals and other substances, excepting metals and tlieir com- binations, which contain carbon, or compounds of carbon and hydro- gen with a trifling admixture of oxygen or nitrogen, the carbon can be detected by ignition with antimonate of potassa, p. 51. The fine powder is mixed in the agate mortar with two to three volumes of the antimonate, if consisting chiefly of earthy matters, and with six to eight volumes if containing metallic sulphides, and then heated to redness in a matrass over the spirit-lamp. The carbon is oxidized at the expense of the antimonic acid, forming carbonic acid, which, combines with the liberated potassa, while if a notable amount of carbon or sulphur is present, a little oxide of antimony volatilizes and partly condenses in the neck. When the substance consists of metallic sulphides, sulphate of potassa and a little sulphide of potas- sium are formed. When cold the matrass is filled nearly to the neck with water, which is gradually heated to boiling. The carbonate and sulphate of potassa dissolve, with part of the undecomposed antimonate of potassa, while most of the latter remains with the earths and metallic oxides. To the quite warm solution a few drops of nitric acid are added, which causes effervescence, more or less lively according to the amount of carbon present. Not a bubble will be seen to ascend if the substance contained no carbon, but several will be perceived if a trifling amount of carbon was present. It must be observed, how- ever, that the solution should be warm enough to allow the carbonic acid to escape. Carbonates vary as to their behavior in the matrass. When com- bined with earths or metallic oxides the carbonic acid frequently escapes below a red-heat, while many of the oxides become more highly oxidized, like protoxide of iron. Carbonate of magnesia is completely decomposed at a red-heat; carbonate of lime only im- perfectly, but it can be entirely decomposed by moistening the unde- composed salt with water and again strongly igniting it. Carbon- ates of the fixed alkalies, strontia and baryta, alone are not altered; carbonate of ammonia sublimes unchanged. All the non-volatile carbonates are decomposed on coal; the car- bonates of the alkalies and baryta fuse, sink into the coal, evolve carbonic oxide, and react very strongly alkaline on moistened litmus paper. Carbonates of the alkalies fuse with silica on platinum wire, or on coal, with effervescence to a clear, colorless glass ; they also yield their carbonic acid with effervescence when fused with borax or S. Ph., as do also the other carbonates. The simplest method of detecting carbonic acid with certainty in BOEOBT AND BOKACIC ACID. 315 any substance consistd m pouring a little dilute nitric acid upon it in a glass vessel and observing whether any effervescence ensues ; in case sulphides are certainly absent, dilute hydrochloric acid may be used. The glass should be slightly heated if no gas is otherwise evolved. It is not well to use concentrated acids, since many car- bonates are only soluble in dilute acids, e.^. witherite. Examination for C&rbon in Metallurgical Products. In raw iron, steel, and lears, the carbon, whether chemically com- bined, or only disseminated j» while hot is frequently colored by the metallic oxides present. The^ are scarcely attacked by S. Ph. ; with soda they fuse with efferves cence to a clear glass. The minerals enumerated under opal, b, yield more or less water in the matrass and lose their lustre. In the forceps they are infusi- ble, and if quickly heated decrepitate. With the fluxes they behave like the preceding. The silicates, both natural and artificial, can be recognized by means of S. Ph. and soda. They are nearly all decomposed by S. Ph., the bases combining with the free phosphoric acid and leaving the silica undissolved. The test is performed on platinum wire by first fusing the S. Ph. to a bead and then attaching to this, while soft, a few very fine splinters of the silicate and treating it for a suf- ficient time in 0. P. If the silicate can be thus decomposed the bases dissolve, leaving a silica skeleton, which floats in the hot, clear bead.* If the bases yield with S. Ph. at a certain saturation, either by flam- ing, or on cooling, a milk-white or opalescent bead, e. g., lime, mag- nesia, glucina, or yttria, the bead will be more or less cloudy on cooling, and the presence of separated silica must be ascertained while it is hot. Should the silicate not be decomposed thus, it must be tested in powder, when, if decomposable, it will leave a gelatinous residue of silica. Silicates of which the bases are chiefly zirconia, cannot be perfectly decomposed, even in fine powder, and their silica is best found as described under zirconia, p. 163.f When a substance contains but little of a silicate, or only some * J. Hirschwald considers that this reaction has no analytical importance (Jotirn. f.pralet. Chem., 1890, p. 367), but experience shows it to be in very many cases a sure test for silicic acid, even though by long blowing no Inconsiderable amount ol this acid does dissolve iu S. Ph. f Certain silicates rich in alumina are also not decomposed by 8. Ph. The action of 8. Ph. varies with different silicates ; those of the heavy metals are generally easily decomposed; those of alumina, the alkaline earths and the alkalies, less easily. Wben a fine powder is tested the reaction may be indistinct, because the^ silicic acid gradually dissolves in the 8. Ph. SULPHUB AND SULPHUKIC ACID. 31& disseminated quartz, the silica will be dissolved and the S. Ph. bead shows no signs of separated silicic acid, but it may be detected in the wet way, by proceeding as directed for silicates under lime, mag- nesia, and alumina. The silica when thus separated can be easily recognized by means of S. Ph. or soda. With soda on coal and on platinum wire the silicates dissolve with effervescence, some perfectly, some only partially. For special descriptions, vide p. 88. When a compound of oxidized substances, which are not reducible by soda, contains a sufficient amount of a silicate, a slight efferves- cence may be observed when testing it with soda, from which the presence of silicic acid maybe inferred, provided the substance is free from other acids that withstand the fire. It is, however, always safer to employ the wet way. In silicates the silicic acid can also be found by mixing 1 part, finely powdered, with 2 parts of powdered cryolite or fluorite, free from silica, heating the mixture with ir-e parts of concentrated sulphuric acid in a platinum crucible moderately (not so that it spirts) over the alcohol lamp, and holding near thy surface of the crucible a drop of water in the loop of a freshly ignited platinum wire. A white film of hydrous silicic acid will form on the drop, through decomposition of the escaping silicon fluoride. 6. SuLPHtTK, S, AND SULPHUEIC ACID, S 0'. Their occurrence in the mineral kingdom and in metallurgical products. Sulphur occurs in nature : a. As native Sulphur, S, frequently rendered impure by quartz, lime, iron, coal, water, etc. 5. Combined with many metals. Sulphuric acid occurs in combination with alkalies, earths, and metallic oxides, ill the minerals containing sulphur or sulphuric acid have been mentioned. Among metallurgical products sulphur "forms a' chief ingredient of the matts (Steine and Leche), which have already been enumer- ated under the respective metals, and is occasionally an accessory ingredient in certain raw metals and compounds of metals, which are to he submitted to further treatment, as in raw iron; also in certain slags. ,.n ■ ^ i i. j. Sulphuric acid constitutes a chief ingredient of artificial sulphates (vitriols), and occurs in greater or less quantity, combined with earths and metallic oxides, in ores roasted on the large scale, which 3S0 PLATTKER'S BLOWPIPE ANALYSIS. are to be treated for their metals, or the production of alum, or sul phate of iron, zinc, or copper. Examination for Sulphur and Sulphuric Acid, Including the general blowpipe characteristics of sulphates and sulphites. Native sulphur fuses very easily in the matrass and sublimes with a brownish color, but becomes yellow again on cooling; foreign ingredients, if non-volatile, remain behind. Ignited on coal it burna with a bluish-flame, evolving sulphurous acid, which isirecognized by its characteristic pungent odor. In its combination with metals sulphur can be detected in various ways: a. In certain cases by heating the substance strongly in the closed tube, p. 62. Some sulphides containing a high proportion of sul- phur yield a sublimate of the latter,'«. g., Pe S'', Mn S% Cu S. If the sulphur is combined with volatile metals, as mercury or arsenic, it sublimes in combination with, the metal, and the sublimate may be recognized by its color, vide sulphide of arsenic, pp. 63 and 304, and cinnabar, pp. 63 and 263. When the sulphur is combined with antimony a strong heat produces the sublimate 2 Sb'' S' -j- Sb^ 0", already mentioned, p. 62. b. By roasting in the open tube, p. 63, et seq. Although a tri- fling amount of sulphur may not always produce the odor of sul- phurous acid, yet the latter will redden an inserted strip of moist- ened Ijlue litmus paper. Substances which contain only a small amount of metallic sulphides and yield no sulphurous acid when in fragments, will do so if treated in the powdered state.* c. By heating the substance on coal in 0. F. If there is but little sulphur, however, the odor of sulphurous acid will not always be perceptible. d. In most cases even a very little sulphur may be detected by fusing the powdered substance with 3 to 3 parts soda, perfectly free from sulphate, p. 46, and one part borax on coal in E. P., provided no selenium is present. In the case of easily-fusible metals, which contain only finely-disseminated sulphides and cannot be pulverized, e.g., raw lead, black copper, etc., a fragment' the size of a mustard- seed or small pepper-corn is used; in case of metals that fuse with difiSculty, as raw iron, the necessary amount must be obtained by * Certain sulphates and sulphites yield sulphurous aoid in the open tube, but these, if minerals, are easily distinguished from sulphides by their appearance. BXAMIlfATION BOB SULPHUR AND SULPHURIC ACID. 321 filing. While the powdered substance is fused with the soda and borax in E. P., or the glass treated by the side of the metal for some time, sulphide of sodium forms, which immediately yields a sulphur reaction when the fused mass is removed from the coal, pulverized, placed on a bright sheet of silver and moistened with water. Sul- phuretted hydrogen is evolved, which colors the silver quite black, with sulphide of silver, if a notable amount of sulphur is present ; but if less is present, only dark-brown or yellow. The resulting stain may be readily removed by rubbing it with moistened charcoal or fine bone ash. The borax acts advantageously by preventing the sulphide of sodium from sinking into the coal and by forming with it a mass which is readily removed. Since selenium forms selenide of sodium, which has a similar eliect on silver *, the substance must always be previously tested alone on coal, to ascertain whether a selenium odor is perceptible. Should selenium and sulphur occur together, the test for sulphur must be performed in the open tube and the formation of sulphurous acid ascertained by the odor, or with moistened litmus paper. The sulphates behave variously in the matrass and on > ' coal. The sulphates of alkalies, alJcaline earths, and lead, are not at all decomposed in the matrass. An imperfect decomposi- tion ensues with the salts of other strong bases, viz.: protoxides of iron and manganese and oxide of zinc; the heat requisite for their complete decomposition cannot be produced. The salts of non-alka- line earths and the weaker metallic bases are more or less readily decomposed. When the salt suffers partial decomposition sulphurous acid is evolved and may be recognized as usual ; with a stronger heat anhydrous sulphuric- acid also escapes and appears as oily drops when cold. On coal, especially in K. P., the sulphates of the fixed alkalies and alkaline earths are converted into sulphides, with an alkaline reac- tion, and the former, after sinking into the coal, are partially vola- tilized and form a white coat, p. 69. If moistened with water, or, better still, dilute hydrochloric acid, these sulphides evolve sulphu- retted hydrogen. The remaining sulphates evolve sulphurous acid and leave partly earths or metallic oxides, partly reguline metals, or metals containing sulphur, provided the reduced metal is not vola- tile; if it is, a coat of oxide is deposited. The sulphites are all decomposed in the matrass, leaving ^ '" either pure oxidei, or a mixture of basic sulphates with ♦According to Bunsen, tellurium causes a similar reaction, and Tollens (Ber. d. deutsch. chem. Gesellsch. Jahrg. 6, p. 593) advises the use of an oil- or oandle-flAmr>. because coal gas sometimes contains enough sulphur to darken the silver. 323 plattnek's blowpipe analysis. sulphides, so that after ignition the sulphites of the alkalies or alka- line earths evolve sulphuretted hydrogen, ii moistened with dilute hydrochloric acid. On coal they behave like the sulphates. Sulphates and sulphites fused with soda on coal in E. F. yield a strongly hepatic mass. For 1 part of the substance 2 to 3 parts of soda are used. Compare also p. 88. When the bases of the salts in question produce no coloration in the glass fluxes, the acid can be detected by forming with soda and silica on coal in R. F. a bead, which is perfectly clear and colorless, and then fusing this bead with a little of the salt in E. F. and observing the color of the cold glass. The acid is reduced, forming sulphide of sodium, which produces a yellow to dark-red color. Should the bases be metallic oxides which color the fluxes, the salt must first be decomposed by mixing it with once or twice its amount of soda, igniting the mixture in 0. F. on platinum foil or wire, dissolving the resulting sulphate of soda in a few drops of water, evaporating the clear solution to dryness on platinum foil, or in a porcelain dish, and testing the salt as above with silicate of soda. Dana has proposed the following test for sulphur (Chem. Gaz., 1851, p. 459). The substance is fused with soda in R. F., the assay moistened with a drop of water in a watch-glass and a bit of nitro- prasside of sodium, as large as a pinhead, added. If sulphur in any form was present a purple color will be produced, to which Playfair first called attention. In order to determine whether the sulphur in a mineral is present as a sulphide or sulphate, von Kobell recommends that the powdered substance should be fused with potassa in the platinum spoon before the blowpipe. The spoon with its contents is then placed, with a strip of sheet silver, in a small porcelain vessel and covered with water. The mass dissolves, and after some time the silver will either become black, or remain bright. In the former case the sub- gtance contains a sulphide, e. g., helvite, etc. ; in the latter caee a sulphate, provided the presence of sulphur has been already ascer- tained by the test with soda on coal. Naturally the substance must be perfectly free from any ingredient which could have a reducing action. SELENIUM. 333 7. Selenium, Se. Its occurrence in the mineral kingdom. Selenium occurs mostly only combined with metals; in clausthal- ite, tilkerodite, zorgite, and lehrbachite, vide lead; berzelianite, umangite, crookesite, and chalcomenite, vide copper; tiemannite, vide mercury; naumannite and eucairite, vide silver; guauajuatite, vide bismuth. It sometimes forms an unessential ingredient of tellurium minerals, and certain galenas and pyrites. It is found also with sulphur and arsenic on the island of Lipari, and is said to have been found native in Mexico. Examination for Selenium. The test for selenium is so simple that even a trace of it can be detected in any substance. A bit is heated on coal in 0. F. and immediately held undjr the nose, when any selenium present will yield the peculiar horse-radish odor of the gaseous oxide, p. 67. If the substance' contains much selenium, brown fumes, consisting only of finely-divided selenium, will be evident, before the assay begins to .glow ; afterward a steel-gray, metallic coat forms, which sometimea has a red border. Selenium may also be separated from its combinations by heating the substance in the open tube, p. 63, inclining it so that the othei constituents may be oxidized ; the selenium then separates and con- denses in the tube with a red color. If there is much selenium tlie sublimate appears rather steel-gray near the assay. Occasionally also small crystals of selenous acid are deposited beyond the red sub- liniate, but they volatilize at a gentle heat. If sulphur is likewise present it escapes as sulphurous acid and is thus recognized. When a trifling amount of. selenium occurs with tellurium, as in tetradym- ite, and the assay is conducted in the open tube, tellurous acid at first collects on the glass, and after continued heating with the blowpipe this appears to be mingled with a red substance, which consists of selenium. Selenates and selenites are reduced in the E. F. on coal to selen- ides, which emit a distinct horse-radish odor. With addition of soda the reduction is more rapid. 324 plattnek's blowpipe analysis. 8. Phosphoeus, P, axd Phosphobio Acid, P' 0'. Their occurrence in the mineral kingdom and in metallurgical products. Phosphoric acid is always found in nature in combination with bases, and occurs as an essential constituent in various minerals, which have been enumerated. Many slags, especially from iron production, contain this acid. Examination for Phosphorus and Phosphoric Acid, Including the general blowpipe characteristics of phosphates. The examination for phosphorus occurs chiefly in case of raw iron. A fragment of the iron weighing about 100 milligr. is dis- Bolred by warming it with nitric acid, which converts the phosphorus into phosphoric acid and leaves the graphite behind. After evapo- rating to dryness in a porcelain dish, the dry mass is strongly heated, until it evolves no more acid vapors, and is then tested for phos- phoric acid, vide a to c, below. Phosphates are not decomposed by ignition in the matrass, but some are fusible. In the forceps, or on platinum wire, most of them can be fused, especially the acid salts, and they color the flame pale bluish-green, provided the bases produce no coloration. On coal most phosphates can also be fused without decomposition, since the combined phosphoric acid is either not reduced at all, or only very imperfectly. The most evident exampk if this is neutral phosphate of lead, which fuses very easUy to a bead on coal, but scarcely suffers any decomposition ia the E. F.; the bead is crystalline, vide p. 228 et scq. Upon fusion with soda on plati- num wire, or in the platinum spoon, the phosphates yield phosphate of soda and the bases are liberated. The test for phosphoric acid may be variously made : — a. By the pale bluish-green color imparted to the flame, p. 76. I. Bunsen {Ann. d. Chem. u. Phys., vol. 138, pp. 266 and 292) has proposed a test for phosphoric acid, which consists in transfer- ring the powdered substance, thoroughly dried by heating, to the drawn-out portion of a tube, somewhat larger than that represented in Fig. 76, and adding a bit of magnesium wire several millim. long, which must be covered by the assay. This spot is then heated B. B. until the glass melts, best with a somewhat reducing flame in which this part of the tube is held; magnesium phosphide is formed, sometimes with a visible glow. When cold the fused part of the tube is crushed between paper. PHOSPHORUS AND PHOSPHORIC ACID. 325 laid in a porcelain dish and moistened with a few drops of water; if phosphoric acid was present the well-lcnown odor of phos- phuretted hydrogen will be evolved. In lack of magnesium a bit of sodium, carefully freed from naphtha and rolled to a small cylin- der, can be used. The Bunsen flame can also be employed. c. The wet way may be used to detect phosphoric acid. Substances consisting chiefly of earths or metallic oxides are treated by tritu- rating forty to fifty milligr. in fine powder with five parts by volume of a previously prepared mixture of four parts by weight of soda with one of silica (as proposed by Berzelius for the quantitative sep- aration of phosphoric acid from alumina), in the agate mortar, transferring it to a soda-paper cylinder, p. 43, and fusing it in 0. F. on coal to a clear bead. The bead is pulverized in the steel mortar, or between paper, and boiled in a small porcelain dish with a suffi- cient quantity of water. Phosphate of soda and the excess of soda dissolve, while in presence of alumina, silicate of alumina and soda, with other earths or metallic oxides, remain behind. If the substance contained little or no alumina and no sesquioxide of iron, a notable amount of silicic acid is dissolved, but this does not affect the determination of the phosphoric acid in the liquid. "When the solution is complete the dish is removed from the flame, and after the undissolved parts have settled the liquid is either filtered or care- fully decanted, with the aid of a glass rod, from the residue into another small dish. If there is reason to suppose that much silicate of soda has been dissolved, it is well to boil the decanted liquid with addition of carbonate of ammonia, when the silica separates in a gelatinous state. After filtering this out, the solution is supersat- urated with acetic acid and stirred with some acetate of lead, when, if the phosphoric acid amounts to several per cent., a white precipi- tate of phosphate of lead is at once formed, which is collected on a filter, dried and fused in a shallow cavity on coal. If it has been well washed a white or yellowish globule, with a crystalline surface, is obtained, which behaves like phosphate of lead, p. 228, et seq. It may further be tested with boracic rcid and iron.* When the precipitate formed by acetate of lead is so trifling that it cannot be removed without partially destroying the filter, which is to be avoided, as it would then be rendered impure by the silica of which the filter ash is chiefly composed, a drop of dilute sul- phuric acid must be added, so as to produce a mixture of sulphate and phosphate of lead, in such quantity that it maybe readily trans- * The solution, perfectly freed from silicic acid, may also be made very feebly acid with nitric acid and some of it added to a nitric acid solution of molybdate of ammonia, when a finely pulverulent, bright-yellow precipitate of phosphomolyb- date of ammonia will form, either at once or in a short time. 326 PLATTNER'S blowpipe AN'ALTSIS. ferred from the filter to the coal. When this is fused B. B. the sul- phate is reduced partly to sulphide of lead, which soon Tolatilizes. and partly to metallic lead, which gradually volatilizes and leaves small globules of phosphate of lead, that can be recognized with the aid of the magnifier, by reason of its characteristic qualities. When the amount of phosphoric acid is supposed to be very small, a larger quantity of the substance, about 100 milligr., should be fused with five times its volume of the mixture of soda and silica, in two or three portions, and the fused beads then treated as before. This is especially necessary with many iron ores. Any arsenic acid pres- ent is reduced and volatilized, while any sulphuric acid forms sul- phide of sodium, which goes into solution and yields sulphide of lead, since it is not decomposed by the acetic acid. The sulphide of lead does no harm, however, as it is volatilized on the coal and leaves the phosphate of lead alone. 9. CHLOEIIfB, CI. Its occurrence in the mineral kingdom. Chlorine is always found in nature combined with other elements. The minerals containing it as an essential constituent have been enumerated. Examination for Ohlorine, Including the general blowpipe characteristics of chlorides and chlorates. Most of the chlorides are fusible in the matrass. Those free from water are more or less volatile ; the chlorides of the alkalies, alkaline earths, manganese, copper, and some others, are not decomposed; chlorides of gold and platinum are reduced. On platinum wire and coal the chlorides, even those which with- stand the heat in the matrass, are more or less readily decomposed into oxides and hydrochloric acid by the 'vapor of water in the blow- pipe flame, or are reduced, especially on coal. Many are also either entirely or only partially volatilized, and form a coat, p. 69. The chlorates fuse very easily in the matrass, and when the base is an alkali, alkaline earth, or other strong bas^ yield oxygen at a red-heat, which causes a glowing splinter to bum when introduced into the mouth of the matrass ; after strong igni- tion, continued for a sufficient time, pure chlorides remain. Salts of weaker bases evolve oxygen and chlorine, and leave basic chlorides EXAMINATION FOK CHLOKIlfE. 327 On coal the chlorates detonate more violently than the nitrates and leave neutral chlorides, if the bases are powerful ; the feebler basea remain as basic chlorides. According to Berzelius, chlorine may be detected in its compounds by dissolving oxide of copper in S. Ph. on platinum wire with the O. F., until the glass is opaque, and then causing the substance ulider examination to adhere to the soft bead, which is then treated with the tip of the blue flame. If chlorine is present the bead will be surrounded with an intense azure-bine flame of uhlovide of copper, which volabilizes so long as chlorine remains. A fresh addition of the substance will reprodiice this reaction. Bromine, p. 77, is the only other body occurring in minerals which produces a similar flame. By this simple test chlorine can be detected with certainty in earths, oxides, and salts. When the substances contain little chlorine, or in case of com- pounds which injure the platinum when heated, a little of the powder is mixed with one-third its volume of oxide of copper, tritu- rated iL the agate mortar with a little water, and a few drops of the mixture spread upon coal with the pestle. The mass is dried B. B., without heating it to redness, and then the blue flame is directed immediately upon it. when the azure-blue flame of chloride of cop- per appears as before. The flame is at first rather greenish-blue, but soon becomes azure-blue. When the compound contains no chlorine there will be at most only a green coloration from copper oxide. Chlorides like chloride of silver, which cannot be powdered, must be beaten as thin as possible between paper, cut up with the scissors, and treated on coal with water and oxide of copper as above. 10. BROMINE; Br. Its occurrence in the mineral kingdom. Bromine has thus far been found in minerals only combined with «ilver, in bromyrite and embolite, vide silver. Ezamination for Bromine, Including the general blowpipe characteristics of the bromides and bromates. Bromides and bromates behave like the corresponding chlorides and ehlorates in the matrass. On coal the bromates detonate with some violence and leave neutral, or, in case of weaker bases, basic bromides. Bromides of potassium and sodium give a white coat on coal, p. 69. 328 plattner's blowpipe analysis. Many bromides are either yolatilized or decomposed on platinum wire, or on coal, and diffuse an offensive odor, similar to chlorine. According to Berzelius, they afford with S. Ph. and oxide of copper the same reactions as the chlorides; the flame has not a pure azure- blue color, however, but inclines to green, especially on the edges. AVhen all the bromine is gone the green flame of the oxide of copper alone remains. To distinguish bromides from chlorides with certainty, Berzeliua has proposed to fuse them in the matrass with bisulphate of potassa, when bromine and sulphurous acid are liberated and the matrass is filled with reddish-yellow vapors of bromine, which can be recog- nized by the similarity of their odor to that of chlorine, notwith- standing the sulphurous acid. Bromide of silver forms an exception, as it yields very little bromine, but it may be distinguished from chloride of silver by the asparagus-green color which it assumes when exposed to the sunlight, after fusion with the bisulphate of potassa, p. 271. When very little bromine is present the matrass should be held vertically, after the fusion, so that by looking down through it s thicker stratum of the vapors may be observed than could be seen by looking sideways through the wide part. Bromine can also be detected by using bismuth sulphide, p, 373; yellow bismuth bro- mide is formed. 11 . IODI>"E, I. Its occurrence in the mineral M?igdom. Iodine occurs in the rare minerals iodyrite, vide silver, in schwartzembergite, vide lead, and coccinite, vide mercury. EKamination for Iodine, Including the general blowpipe characteristics of the iodides and i^dates. Most iodides can be fused, but not readily volatilized, in the mat- rass. In presence of water, or an iodate of a weak base, vapors of iodine occasionally result. The iodates are easily decomposed. In the matrass the salts of the alkalies and alkaline earths evolve oxygen and leave slightly alkaline iodides. The other iodates at the same time evolve \'iolet iodine vapors and leave basic iodides, or only oxides. On coal the ■ iodates deflagrate slightly and leave either iodides, or, in case of weaker bases, residues free from iodine. Many iodides bHlmve like EXAMINATION POR IODINE. 339 the corresponding'bromides, p; 328, when treated on platinum wire or coal. According to Berzelius, iodides tested with a bead of S. Ph. con- taining oxide of copper, produce an intense green flame, p. 75. When iodides are fused in the matrass with bisulphate of potassa, the iodine is partly sublimed and partly fills the matrass with violet vapors, while sulphurous acid is simultaneously evolved. The test is so delicate that small quantities of iodine may be detected in salts, etc., but iodide of silver is only partially decomposed ; violet vapors are, indeed, liberated, but most of the iodide of silver collects beneath the fused acid salt to a drop, which retains its yellow color in the sunlight, p. 373. With bismuth sulphide iodides in the open tube give a scarlet- red sublimate of bismuth iodide, p. 373. 13. Fluoeine, p. Its occurrence in the mineral kingdom and in metallurgical products. Fluorine always occurs in combination with other bodies. It forms an essential constituent of various minerals already enumerated. In many smelting processes slags are produced which contain more or less fluoride of calcium, arising from fluorite abundantly dissem- inated in the ores, or purposely added, and which has not been entirely decomposed by the silica present. Ezaminatiou for Fluorine or Hydrofluoric Acid. When fluorine occurs in trifling quantity with weak bases and a little water in minerals, it is only necessary to heat a small quantity of the substance in the closed glass tube, in which a strip of moist- ened Brazil-wood paper is inserted. The gaseous fluoride of sili- cium, expelled by the heat, is decomposed by the vapor of water, and a ring of silica is deposited near the assay, while the escaping hydro- fluoric acid colors the paper straw-yellow. This reaction is pro- duced when only three-fourth per cent, of fluorine is present, as in mica. When no reaction for hydrofluoric acid is obtained, either on the glass or the paper, in the closed tube, Berzelius's test with S. Ph. must be employed. The finely powdered substance is mixed with S. Ph., previously fused on coal and also pbwdered, and the mixture heated in the open tube, so that the flame may be carried inside of thd tube upon the substance. Under the solvent action of the 330 plattkee's blowpipe aijalysis. 8. Ph. upon minerals free from silica, hydrofluoric acid is formed, which passes through the tube and can be recognized both by ita peculiar, pungent odor and by its effect on the glass, which it attacks and renders dull, especially where any moisture has collected. The escaping air will also turn Brazil-wood paper yellow. In presence of silica, e. g. in native silicates and slags, fluoride of silicium is formed, which is decomposed by the water that separates from the products of combustion of the flame. The separate silica dissolves in the water, which condenses on the glass and is gradually evapo- rated by the hot gaseous products, leaving distinctly perceptible silica behind. When the tube is washed out and dried with blotting paper, the glass itself occasionally shows dull spots, where it was attacked by hydrofluoric acid. A strip of moistened Brazil-wood paper inserted in the tube before the assay is begun is colored yellow. The heat must be suflBcient to fuse the mixture, and it may easily happen that a very thin glass tube will soften and contract, so as to interrupt the operation before any result is attained. To remedy this Smithson fastens some platinum foil in the end of the tube with wire so as to form a semi-cir- cular tube as in Fig. -77; where, _,.^._^ ,.„,_. ,^'^'''''- however, the platinum is simply inserted into the tube without the wire. The assay is placed on the plutinum, and the blast so directed that the products may be driven into the tube. This affords an advantage, inasmuch as the assay is fused without coming into contact with the glass. 13. CXAlfOGEK, Cy. COSIPOSITION- = K". Its occurrence in metallurgical products. When iron ores are smelted in blast furnaces with charcoal the carbonate of potassa in the coal is. liable to form cyanide of potas- sium; this is deposited in the conduits for the furnace gases and consists chiefly of a mixture of potassium cyanide, cyanate and car- bonate, ammonium carbonate and coal. Cyanogen also occurs combined with titanium and nitride of ti- tanium in small crystals and amorphous masses, in the cadmia of certain iron blast furnaces, vide titanium, p. 280. EXAMINATION FOK CYANOGEN. 331 Examination for Cyanogen, Including the general blowpipe characteristics of cyanides. Cyanides heated to low redness in the closed tube or matrass are in general decomposed, becoming charred, and evolving cyano- gen, ammonia, water, and nitrogen. The anhydrous cyanides of the alkalies and alkaline earths suffer no change at a red-heat, and cyanide of potassium may even be more strongly heated. On coal, and in the platinum spoon at a high temperature, all the cyanides are decomposed, but those of the alkalies slowly, and the liberated cyanogen is consumed. « The wet way is best suited for detecting cyanogen in the salt above referred to, as being formed in smelting iron ore with charcoal. A little of it is dissolved in water and decanted after the residue of coaly matters and particles of iron has settled. The solution is then acidified with hydrochloric acid, when a little prussic acid is evolved, and effervescence ensues if carbonate of potassa was present. Ta the acid solution a few drops of a solution of proto-sesquioxide of iron (magnetite, or siderite ignited in the matrass) in hydrochloric acid are added and afterward solution of potassa in drops, when the presence of cyanogen will immediately afford Prussian blue. The test may also be made by testing a part of the dissolved salt for car- bonic acid with hydrochloric acid alone, and -adding to the other portion a few drops of a solution of protoxide of iron, when a grayish-green precipitate is produced. By then adding a slight excess of .potassa solution, shaking it up and adding hydro- chloric acid to strongly acid reaction, the Prussian blue is obtained on agitating it anew. The latter method is to be preferred when little cyanogen is present, as none of it is then lost by the formation of prussic acid. According to Froehde (Poggend. Ann. vol. 119, p. 332) cyanogen can be surely detected in its insoluble compounds as follows: Some sodium thiosulphate is dehydrated on a platinum wire loop, a little of the compound added, and treated a little while B. B. The mass is then dipped into a few drops of ferric chloride solution to which a little hydrochloric acid has hetu added. In presence of cyanogen an intense blood-red color appears around the wire and gradually spreads through all of the ferric chloride. The heat must not be too long continued, lest the resulting sodium thiocy- anate be decomposed. The assay must be taken from the flame when the sulphur begins to burn. 332 plattnee's blowpipe analysis. III. Examples showing the method of detecting the constituents of various compounds with the help of the blowpipe. ■ The examination of a doubtful compound with the aid of the blowpipe must be conducted according to certain rules, which hare been already described in detail on p. 59, et seq. Such an examination should be preceded by a test of homoge- neity and a determination of the most important external indications of ttie substance, for which it may be said that a general acquaint- ance with chemistry and mineralogy is indispensable. Generally the external appearance of substances will show whether they consist of salis or similar comiinations, of silicates, aluminates, metallic oxides, sulphides, selenides, arsenides, or of alloys. After leatning the plan to be pursued in the examination of a substance belonging to any of the above classes, it will not be diflS- cult to detect the separate constituents. In the following examples, at least, the most frequent combinations have been considered as much as possible, and they will therefore serve to show how such an examination is to be instituted and conducted, after first deciding, from the external appearance of the substance, to which of the above classes it belongs. A. Oxysalts, Chlorides, and Fluorides. The method of examining these compounds with the aid of the blowpipe is in general as follows: 1. A small portion is gradually heated to redness in the matras8, and all resulting phenomena are noted, p. 60, et seq. 2. If apparently easily fusible, the substance is tested on platinum wire, to see whether it colors the flame ; if fusible with difficulty, it is held in the platinum forceps. Should no decisive reaction be obtained the substance must be freed from water by ignition, powdered, and moistened with a proper acid, p. 72, et seq. 3. A small portion is treated B. B. on charcoal, being previously powdered if it has decrepitated in the matrass. At first the 0. P. ifl employed ; if no particular change takes place the E. F. is then used, and any resulting phenomena noted, p. 65, et seq. Simple salts may frequently be at once recognized by these testa^ OXYSALTS, CHLOKIDES, AND FLUORIDES. 333 and both tlie bases and acids detected, especially with the help of reagents; and in the case of minerals of complex composition a conclusion as to their chemical constitution can be also formed. Examples. Sulphate qfpotassa. — The crystallized salt heated to low redness in the matrass de- crepitates, but is infusible and yields nothing volatile. (The bisulphate fuses, and at a high heat evolves fumes of sulphuric acid.) A little of the powder fused on platinum wire colors the flame violet, p. 74. Another portion of the powder treated B. B. on coal with the O. F., fuses, eiFervesces, and sinks entirely into the coal, which on continued blowing is coated white, as if by a sulphate of an alkali, or by some volatilized chloride, bromide, or iodide, p. 69. This coat disappears under the R. F. with a violet flame. The I ase of the salt is therefore most probably potassa. Upon moistening the spot where the salt has sunk into the coal with water an hepatic odor is evolved, while if this spot is cut out and laid on moistened silver foil the silver turns black. In either case a sulphide is recognized, which has been formed by the reduction of the salt on coal, and we have, therefore, mlphate of potassa. Note. — It has been already remarked, p. 74, that caesium and rubidium salts color the flame in a manner very similar to potassa salts, so that they might readily be con- founded with each other. The great resemblance of the results obtained with indiao solution and cobalt glass, p. 103, renders these tests also unreliable, and in doubtiu. cases the only means of distinguishing between the salts is the examination with the Ipectroscope. — To determine whether a salt of an alkali it free from baryta or strontia, which sink with the alkali into the coal, and cannot therefore be detected by the simple tests above described, a small portion is dissolved in water, and any residue reserved for further examination. (In case of sulphates this may consist of sulphate of baryta or strontia.) Should the acid be one which forms soluble salts with baryta and strontia also, a few drops of sulphuric acid, or a solution of sulphate of potassa are added to the clear solution, when a cloudiness will be produced if either of the above earths is present. Should this be so, a larger quantity of the salt must be dissolved in water, sulphuric acid added to the solution, and the precipitate, after settling, filtered out, washed, and tested, according to p. 113 or 116. Nitrate df potassa (saltpetre, nitre). — It fuses easily in the matrass to a clear fluid, and when more strongly heated boils and yields oxygen, but in such small quantity ihat it cannot be recognized by a glowing splinter of wood. This indicates an alkaline base. On platinum wire gradually diminishes in volume, owing to decomposition, vields no odor, but colors the flame violet, thus indicating potassa as the base (vide note, above). On coal deflagrates very vividly and leaves a white salt, which on continued blow- ing sinks into the coal, but yields neither a coating, nor a reaction on silver foil. Taken in connection with the behavior in the matrass and on platinum wire, this shows that the acid can only be nitric add, and this is established by a special test with bisulphatt of potassa, p. 310. Potassium chloride {syhjite). In the matrass begins to melt at a high tempera- ture, but yields no oxygen or water. On platinum wire melts easily, with a violet flame, and volatilizes in white fumes. The base is therefore potassium. 334 plattxek's blowpipe analysis. On coal fuses without deflagration, sinks into the coal and is gradually volatil- ized, forming a white coat which disappears in part when touched by the flame, to which it gives a violet color, and in part reappears as a coat. Since the mass that has sunlt into the coal gives no hepatic reaction on silver, the whole behavior points to a combination with chlorine, bromine or iodine. A test with a bead of S. Ph. containing copper oxide, p. 327, gives a fine blue flame. A small portion heated with bisulphate of potassa in a matrass yields only feebly colored vapors, with an odor of clUorine, and a test with bismuth sulphide in the open tube gives a white bismuth chloride sublimate. (Bromide of potassium would give a yellow, iodide a red sublimate, and the latter would give a green flame with S. Ph. and copper oxide). Carbonate of soda (natron, trona, iJiermimatrite, urao), — In the matrass yields neutral water. The dehydrated salt is infusible at low redness. Fused on platinum wire it colors the flame intense reddish-yellow; the base is therefore apparently «xii, which fact is established by making special tests for potassa and lithia, p. 103 and 110. Fuses on coal without deflagration, sinks in, but on continued blowing yields no co»t ; the salt, when cut out from the coal and moistened on silver foil, yields a sulphur reac- tion, if the salt was not quite free from sulphuric acid. Since the foregoing behavior does not indicate the acid, it must be further examined with litmus paper, hydrochloric acid, or silica. If placed on red litmus paper and moistened, it reacts alkaline ; it shows carbonic acid by effervescing strongly with dilute hydrochloric acid ; with silica on coal it fuses with effervescence to a clear bead, which after treatment in R. F. becomes yellowish on cooling, unless the salt was quit*, free from sulphate of soda, p. 322. Biborate of soda (borax). — Yields much neutral water and puffi up in the matrass. The natural salt blackens in consequence of the charring of adherent organic matter, On platinum wire and coal puff's up strongly at first, and then fuses to a clear, color- less bead, producing an intense reddish-yellow flame — goda. The dehydrated salt, tested with sulphuric add on platinum wire, affords a distinct boracic acid flame, p. 75. Sulphale of ammonia {mascagnite). — Decrepitates slightly in the matrass, then fusei and is decomposed, evolving ammonia, which may be recognized by the odor and wilt red litmus paper, and also some water. The remainder disappears, forming a subli mate of sulphite of ammonia, generally mingled with some sulphate. When fused with soda on coal the salt is decomposed, an ammoniacal . odor ig evolved, and the soda which sinks into the coal affords a strong sulphur „ reaction on silver foil. Chloride of ammonium {sal ammoniac). — In the matrass sublimes, without fusing, leaving no residue if pure. A burnt odor may sometimes be noticed at the mouth ui the matrass. If another ixirtion is treated with soda in the matrass ammonia is evolved, p. iI2. Upon testing some of the volatile compounds with a S. Ph. bead containing oxide of copper, using not too little of the substance, an azure-blue chloride of copper flame is obtained. Carbonate of baryta (witherite). — Sometimes yields traces of water in the matTas* but is otherwise unchanged. According to p. 114, fuses easily to a bead in the forceps, coloring the Same yellowish-green — baryta, p. 75. On coal fuses to a globule, which, however, soon spreads out and ginks into the coal, although not so deep as a salt of an alkali. If cut out the mass then reacts alkaline on litmus paper. It is apparently carbonate of baryta, and this fact is established by its complete solubility, with eifcr vescence, in dflute hydrochloric acid. Any trifling amount of metallic oxides prciont may be detected by testing with the glass flaxes. In borax and S 'Ph. it dissolve* OXYSALTS, CHLORIDES, AND FLUORIDES. 335 readily with effervescence, behaving like baryta, p. 82, and sometimes showing a little iron. Sulphate of baryta {barite, heavy spar), p. 113. Sulphate ofstrontia {celestite), p. 116. Carbonate ofstrontia (strontianite), p. 116. Nitrate of stroniia.—lf free from water of crystallization the salt decrepitates in the matrass and yields only a little mechanically combined water. Upon continued heat- ing the matrass is filled with yellow fhmes of nitrous add, which may be recognized by their odor; the salt fuses, without becoming clear, and boils. (The greenish color frequently assumed by the mass in contact with the glass is only due to the manga- nese contained in the glass, which is attacked by the heated salt.) On platinum wire fuses even at a feeble heat, boils, yields up its nitric acid, and leaves an infusible, white, earthy mass, which is strongly luminous and colors the flame intense red. Deflagrates slightly on coal, leaving a white, earthy mass, which is Inminous when strongly heated, and on cooling has an alkaline reaction on litmus paper. This behavior indicates sirontia and nitric acid as the constituents of the salt. Fluoride (^ calcium {fluar spar). — The ingredients of this compound may be dis- tinctly recognized from the blowpipe characteristics on p. 121, et seq. ; but the following explanatory remarks should be made : Powdered iluor spar, alone on coal, fuses to a globule, which becomes less fusible and acquires an alkaline reaction after longer treatment. Since the behavior in the matrass and forceps and on coal indicates the presence of lime or strontia, a test on coal with soda is necessary, by which these two earths can be readily distinguished, p. 87. Since also, from the whole behavior, it may be presumed that the substance is fluor spar, a special test for fluorine should be made with fused S. Ph., according to p. 329, et seq. Sulphate of lime {gypsum and anhydrite), p. 121. Phosphate of lime with chloride and fluoride of calcium (apatite). The behavior of this mineral is described on p. 123; but the following remarks may be made : 1. Since the mineral produces only an indistinct coloration of tlie flame, a little of the fine powder must be moistened with sulphuric acid and fiiscd in the blue flame on platinum wire, p. 76, when phosphoric acid will be shown. See also p. 324. 2. As the mineral suffers little change when treated alone, it must be tested with borax, S. Ph., and soda, and then the earthy constituent will be shown to consist chiefly of lime. When it .is remembered that the natural phosphates usually contain a larger or smaller amount of chlorides or fluorides, there is reason to make special tests for chlorine, p. 327, and fluorine, p. 329. Carbonate of lime (calcite and aragonite), p. 123. Tungstateoflime{scheelite), p. 125. Sulphate of magnesia (epsomite), p. 13i. Carbonate of magnesia (magnesite), p. 135. Borate of magnesia (boradte), p. 136. Phosphate of ammonia and magnesia, obtained when silicates containing magnesia are examined in the wet way, p. 128, et seq. The dry salt yields water in the matrass, and evolves ammonia before it attains a red heat ; but it does not fuse. On platinum wire it fuses and, if free from soda, gives a pale bluish-green flame of phosphoric acid ; when not otherwise perceptible this color may be produced for a short time if the salt is first moistened with sulphuric acid. On coal fiises with difficulty, yielding its water and ammonia, and leaving an enamel-white bead, if free from cobalt and manganese, lioistened with cobalt solution and ftised in O. F., the bead appears violet by day- light, but red by candlelight. 336 plattner's blowpipe akaltsis. Since the fusibility, the flame and the color with cobalt solution are character- istic for phosphate of magnesia, it follows that the salt is hydrous phosphate of am- monia and magnesia. A test with soda and nitre on platinum foil will show whether manganese is present. Sulphate of potassa and alumina (potash alum). — The blowpipe characteristics of this salt hare been described as far as necessary, on p. 142, but if it is to be used as an example the following remarks should be made . Since the salt at first fuses m the matrass in its water of crystallization, and then yields water and sulphurous acid, it follows that it is a sulphate, and either an acid Bolphate, or one in which the base is not strong enough to retain the acid at a bigli tjmperature. Since, moreover, the dehydrated salt treated on platinum wire produces a violet flame, is infusible, and when ignited in a pure O. F,, after being moistened with cobalt solution, assumes a blue color, it is evident that there are two bases present, viz. : potassa and alumina, which latter, in combination with sulphuric acid, yields its add when strongly ignited. A test with soda in B. F. on coal, p. 320, will perfectly establish the presence of sulphuric acid. Sulphate of am/monia and alumina [ammonia alum), p. 142. Phosphate of alumina (ioavellite), p. 143. Fluoride of sodium and alu/minium (cryolite). — According to p. 140, thife compound yields reactions for soda, alumina, and hydrofluoric add. Further tested with sulphuric acid on platinum wire, it only yields the reddish-yellow soda flame, showing that neither boracic nor phosphoric acids are present. It dissolves perfectly and withont effervescence in hydrochloric acid, being therefore free from silica and carbonic add. Since also neither nitric or sulphuric acids, chlorine, bromine, Or iodine, can be present, because they would have been recognized on coal, it may be assumed that the soda and alumina are combined as sodium and aluminium with fluorine, and this is estab- lished bj' a special test, according to p. 329, inasmuch as a very strong hydrofluoric icid reaction is obtained. It would be superfluous to give here examples of salts of metallic oxides, since their blowpipe behavior is described in detail in the respective places under the varioiu metals. Some of the following may be selected for practice. Sulphate of protoxide of iron, hydrous {copperas), p. 189. Hydrous phosphate and sulphate of iron (diadochite), p. 190. Hydrous arsenate and sulphate nfiron (pitticite), p. 192. Carbonate of iron {siderite), p. 191. Tungstate of iron amd manganese (wolframite), p. 193. Oxide of iron and titanium (titanic iron), p. 193. Niohate of iron and manganese (columhite), p. 194. Hydrous arsenate of cobalt (erythrite), p. 202. Hydrous arsenate of nickel (annabergite), p. 208. Carbonate of zinc (smithsonite), p. 213. Phosphate or arsenate of lead -with chloride of lead (pyromorphite or mimetite), p. 228. Carbonate of lead (cerussite), p. 229. Ghromate of lead (crocoite), p. 229. Molybdate of lead (inulfenite), p. 231. Carbonate of bismuth Qiismutite), p. 241. Hydrous phosphate of uranium, with lime or oxide of copper (autunite or torber- ■nite), p. 245. SILICATES AKD ALUMINATES. 337 Hydrous sulphate of copper (chalcanthUe, copper vitriol), p. 256. Hydrous phosphate of copper, p. 257. Hydrous carbonate of copper (malachite or azurite), p. 257. Hydrous arsenate of copper, p. 258. B. Silicates and Aluiainates. The examination of silicates is performed : 1. In a small matrass ; by observing the remarks on p. 309, the hydrous silicates may thus be distinguished from the anhydrous, 2. In the platinum forceps; attention must here be paid to the observations on pp. 70 to 72, and the remarks on the fusibility of the silicates, p. 100. Some silicates color the flame, owing to lithia boracic acid, etc. ; the soda coloration is only regarded as impor- tant when it is distinct and lasting. 3. With reagents, borax, S. Ph., soda, in certain cases cobalt solution, as well as a mixture of bisul- phate of potassa and fluor spar. The behavior with S. Ph., pp. 85 and 318, is characteristic; likewise with soda, p. 88, et seq. Cobalt solution yields decisive results only in a few cases, more especially mentioned under magnesia, p. 133, and alumina, p. 140. Bisulphate of potassa and fluor spar are used in examining for lithia, p. Ill, and boracic acid, p. 316, when these cannot be seen at all, or only indis- tinctly, by simple heating in the forceps. When the bases cannot be detected with the blowpipe alone the wet way must be brought to assist, either by decomposing the compound at once with hydro- chloric acid, p. 100, if possible, or after first fusing it with soda and borax on coal, p. 94, et seq* The aluminates do not occur very abundantly in nature, and they are tested like the silicates ; their blowpipe charactenstics are also given in the proper places, under magnesia, glucina, and zinc. They can in general be distinguished from the silicates by their complete solubility in S. Ph., and by the fact that they do not aflford a pet feetly fusible compound with any proportion of fioda. Examples. Silieate of lime (MoZlosioniJe).— Heated to glowing in the matrass is unaltered but sometimes yields a little water. In the forceps, fuses on the edges to a semi-trans- * It is not difficult to recognize silicates of the heavy metals, including many slags; and it Li, F, B have been found, the recognition of the mineral becomes de- cidedly easier, especially if attention is paid to the phenomena while testing for fusibility. 338 plattner's blowpipe akaltsis. parent glass; the flame is at first yeUowish, afterwards pale yellowish-red With borax dissolves easily and largely to a clear bead, which cannot be flamed opaque If not quite free from iron the bead is yellowish while hot. In S. Ph. dissolves, with formation of a silica skeleton, to a clear glass, which is opalescent on cooling if strongly saturated. With equal parts of soda fuses with effervescence to a blebby glass, which swells and becomes infusible on addition of more soda. Moistened with cobalt solution and strongly heated in O. F. only shows a blue color on the fused edges. ' ' The above reactions show that wollastonite is a siUoate, since the siUoic acid is recognized by its behavior both with 8. Ph. and with soda. To detect the other constituents the wet way must be employed, vide lime, p. 128. Silicate ofpotassa and alumina (otihodase, adularia).— Alone in the matrass is un- altered and yields no water, unless already weathered. In the forceps fuses only on the edges to a semi-transparent, blebby glass, and gives a more or less intense yellow flame, owing to a little soda. Dissolves in borax very slowly, without effervescing, to a clear glass, sometimeg yellowish while hot, from a trifling amount of iron. By S. Ph. is decomposed per- fectly only when powdered, and leaves a silica skeleton. The glass opalesces on cooling (cf. p. 145). "With soda dissolves slowly with effervescence, to » difficultly fusible, clear glass, scarcely free from bubbles. If finely powdered orthoclase is tested with cobalt solution only the fused portions assume a blue color. These blowpipe characteristics show that the substance is a silicate, in which the silicic acid seems to be combined with alumina (because soluble with difficulty in borax), and with soda (shown by the yellow flame), or perhaps with potassa also, the potassa reaction being concealed by the soda. To decide this latter point a special test must be made, p. 103. The flnely powdered mineral is mixed with pure gypsum, p. 104, moistened, fused on platinum wire, and the flame observed through cobalt glass ; if a distinct violet color is perceptible potassa is present (vide note, p. 333). The wet way must be brought to aid in the examination for other earthy bases, besides alumina, and as even the flnely powdered mineral is not decomposed by hydrochloric acid, a Bufdclent quantity of it must be fused to a clear bead with soda and borax on coal, p. 94, and then treated according to p. 128, et seq. A very trifling amount of lime may then occasionally be found. Some of the mass which has been evapo- rated with hydrochloric acid may also be employed to detect potassa by the wet way, p. 104. Silicate of glucina and alumina (beryl, emerald). — For the blowpipe characteristics of this silicate and the method of detecting its constituents, vide p. 147, et seq. Silicate of yttria, etc. {gadolinite). — For, its blowpipe oharaoteristioa and the method of detecting all of its constituents, vide pp. 157 to 159. Silicate of zirconia izircon, hyacinth), vide p. 162, et seq. Silicate of protoxide of ceriwm, (cerite), pp. 168 and 169. Silicate and borate of lime, magnesia, alumina, and sesquioxides of iron and numganem {axinite). — Yields nothing and is unaltered in the matrass. In the forceps fuses very easily with intumescence, coloring the flame feebly green if held in the tip of the blue flame, and when cold the fused mineral is dark green. After perfect fusion in 0. F. it becomes black. Borax dissolves axinite readily in 0. F., yielding a dark red glass, with a violet shade. After short reduction the glass is yellow, and if reduced on coal with tin it becomes vitriol-green (iron). With S. Ph. in 0. F. leaves a silica skeleton and dissolves to a yellow glass, color- less on cooling ; this glass again fused and then brought into contact with a smsl] crystal of nitre, froths up and assumes a violet color. With soda on coal effervesces and SILICATES AND ALUMINATES. 339 fuses to d black, almost metallic lustrous glass, and on platinum foil reacts strung!} for manganese. The foregoing behavior indicates a combination of silicates ; the bases consisting of an oxide of iron (because the glasses, especially that of borax, appear yellow after short reduction) ; of an oxide of manganese (shown by the color of the borax bead in O. F., as above described, and by the violet color of the S. Ph. glass with the nitre, as well as by the green mass obtained with soda on platinum foil) ; further, of earths (because a comparatively large quantity is required to produce an intense color with the glass fluxes). The earthy bases can, however, only be detected by fusing the mineral with soda and borax on coal, and decomposing the fused mass in the wet way, pp. 128 and 145. By this means axinite is found to contain, besides iron and man- ganese, alumina, lime, and a little magnesia. The green color imparted to the flame, while testing the fusibility of the mineral, indicates boracic acid. By making the special test with bisulphate of potassa and fluor spar, p. 316, its presence is more com pletely established. Lead slag from the Freiberg smelting works. — In the forceps fuses rather easily to t globule, coloring the flame bluish, and sometimes greenish. If the fine powder is moistened with hydrochloric acid and fused on platinum wire within the blue flame there results, if copper is present, the azure-blue flame of chloride of copper. Frag- ments of slag, when cot too large, fuse rather easily alone on coal to a globule, and if this is kept fused for a time in contact with the flame quite a thick coat of oxide of zinc is deposited, which, however, if touched with the flame, shows the presence of oxide of lead by the blue tinge imparted to the flame. With borax in O. F. dissolves readily to a clear bead, dark yellow from sesquioxide of iron, and becoming lighter on -cooling. In S. Ph. dissolves, with formation of a silica skeleton, to a clear glass, also yellow from iron. With soda on coal effervesces and fuses to a black bead, which after longer treatment in B. F. deposits an abundant yellowish coat of oxides of zinc and lead. If moistened upon silver foil the fused mass then reacts strongly for sulphur, vide below. By a reduction assay with much soda metallic particles are obtained, which either consist of pure lead, or, in case copper ia present, behave with boracic acid like an alloy of lead and copper. With soda and nitre on platinum foil a distinct manganese reaction is produced. The foregoing behavior shows that the lead slag consists chiefly of a silicate of protoxide of iron, containing a little oxide of lead, zinc, (copper,) and manganese. Other (earthy) bases present can only be detected with the aid of the wet process. For this purpose about 100 milligr. of the finely powdered slag are fused with soda and borax by the side of a gold button, weighing about 80 milligr., in R. F., accord- ing to p. 9i, and the resulting bead is further treated as directed for silicates under lime, p. 128. By this means alumina, with some lime and magnesia, will also be found. Upon fusing the gold button freed from slag on coal alone, a pure lead coat is ob- tained, and if the remaining button is then treated a short time on coal with S. Ph. in O. F., and the glass reduced a moment with a little tin, after removing the gold button, it will become brownish-red and opaque from suboxide of copper, if the slag was not quite free from copper. The lead slag therefore consists of; silica, protoxide of iron, alumina, lime, {magnesia,) and a little oxide of had and zinc, suboxide of copper, protoxide of manganese, and lulphur (combined with various ingredients). A special test for silver will also show R trace of that metal. The strong sulphur reaction obtained even from quite pure fragments of the slag indicates the presence of sulphide of calcium (and occasionally sulphide of barium) When hydrochloric acid is poured over some of the fine powder in a test glass and th« 340 PLATTNER S BLOWPIPE ANALYSIS. whole stirred with a glass rod, applying heat if necessary, an odor of snlp^uretted hydrogen is at once evolved. Should this not be distinct enough a strip of paper moistened with solution of acetate of lead is laid over tho mouth of the glass, or held within it, to see whether it is rendered brown or black by sulphide of lead. Aluminate of magnesia {spinel), p. 138. ^ Aluminate of glucina (chn/soben/l), p. 149. Aluminate of zinc, magnesia, and iron (gahmte, automalite), p. 215. C. Combinations of Metallic Oxides. The metallic oxides occurring in nature are either pure oxides or hydrates. Some form distinct minerals by themselyes, some when combined with others. Such as can be heated to redness in the matrass without yielding water are oxides, and such as yield water are either hydrates, or oxides containing hydrates. The metallic oxides which occur as metallurgical products, although frequently containing sulphuric acid, or acids of arsenic and antimony, with which a part of the oxide is combined, never contain water chemically combined. The oxides are tested at first alone : a, in the matrass ; b, in the forceps ; c, on coal. If no decisive result is thus obtained the exam- ination is continued with borax, S. Ph., and soda. Examples. Peroxide of manganese (pt/rolasite), p. 175. Peroxide of manganese with oxide of cobalt and water {eartht/ cobalt. Hack), p. 176. Peroxide of manganese with oxide of copper and protoxide of manganese {euprema •mnganese, lampadite), p. 176. Oxides of iron {magnetite, hematite), and hydrated sesquioxide of iron (Umonite), p. 189. Protoxide of iron and magnesia with sesquioxide of chromimn and alumina (chromite), p. 189. Binoxide of tin {cassiterite), p. 235. Froto-sesquioxide of uranium (pitchblende), p. 244. Suboxide of copper (fiuprite), p. 256. D. Metallic Sulphides, Seleuides, and Arsenides. The following plan serves for such compounds : 1. Heating in a closed tube, p. 62; this affords sublimates of sulphur, sulphide of arsenic, sulphide with oxide of antimony, arsenic, mercury sulphide, selenium, selenium sulphide. 3. In the open tube, p. 63; afford- ing sulphurous acid, arseuous acid, antimonious acid, alone and with antimony oxide, selenium and selenous acid, tellurium and tellurous acid, mercury. 3. On coal, observing what is stated on METALLIC SULPHIDES, ETC. 341 p. 65, et scq.; coats are giyen by As, Sb, Pb, Bi, Zn, Sn, Mo, Ag (in part). When necessary to employ glass fluxes sulphides must generally be freed as far as possible from sulphur by roasting. Arsenides can usually be fused beside the flux at once in small fragments. The metals giving characteristic colors, with the glass fluxes which come in this section are : Sb, Pe, Co, Ou, Mn, Mo, Ni, Ag, Bi. Infusible sulphides are : Mn S, Zn S, Mo S'. Examples. a. Metallic sulphides, Protosulphide of manganese {alabcmdite), p. 175. Sulphide uf iron {pyrite and pyrrhotite), p. 188. Stdphide with arsenide of cobalt (cohaltite), p. 200. Sulphide of zinc with sulphides of iron and cadmium (zinc blende, black and brown), p. 212. Sulphide of lead (galena), p. 224. Sulphide of copperandsvlphideofleadwithsulphideof antimony (bournonite), p. 226. Sulphide of copper, iron, and zinc, with sulphide of tin (stannite, tin pyrites), p. 235. Sulphide of bismuth (bismuthinite), p. 240. Sulphide of copper with sulphide of iron [chalcopyrite, bornite), p. 255. Sulphide of copper, iron, zinc, and mercury, with sulphides of antimony and arsenic {tetrahedrite, mercurial), p. 254. ' Sulphide of mercury {cinnal)ar), p. 263. Sulphide of silver (argentite, silver glance), p. 269. Sulphide of silver and copper with sulphide of antimony and a, little sulphide of arsenic (polybasite), p. 269. Sulphide of silver and arsenic {provstite), p. 269. Sulphide of silver and antimony (pyrargyrite, miargyrite), p. 270. Sulphide of iron with sulphide of antimony (berthierite), p. 289. Rohstein from, the Freiberg works. — Yields nothing volatile when ignited in the closed tube. The powder ignited in the open tnhe evolves sulphurous acid, recognized by the smell and with litmus paper. Ou the lower side of the tube quite near the assay a thin white coat sometimes forms, which is not volatile, and resembles antimonate of oxide of antimony, or sulphate of lead. On coal alone in E. F. fuses readily to a globule, and on continued reduction forms two diiTerent coats. One, which is formed first and at a greater distance from the assay, is white, and may be driven about with the 0. P., imparting a blue tinge to the flame when touched by it, and leaving a yellow spot ; it seems therefore to be sulphate of lead. The coat which is formed later is light yellow while hot and yellowish-white on cooling. If the outer edge of it is heated with the B. F. it is driven to another place, tinging the flame azure-blue and leaving a yellow spot of oxide of lead. The greater part of the coat reaching up to the assay consists clearly of oxide of zinc, and if moistened with cobalt solution when quite cold, and cautiously ignited in 0. F., it assumes on cooling a yellowish-green color. By fusing a sufficient quantity of the powder with soda on coal in B. F., a feeble odor^of arsenic may sometimes be obtained. If a portion of the powder is carefully roasted, p. 77, and tested with the fluxes, it will behave as follows : — In borax on platinum wire in O. F. yields a clear yellow glass, showing only iron. This treated in R. F. for a short time with tin, becomes on cooling opaque red from •342 plattner's blowpipe akaltsis. capper ; after longer reduction the copper is reduced out, and the cold glass is then clear and has a pure vitriol-green color, owing to the considerable ^nount of iron present. In S. Ph. in 0. F. on platinum wire yields a glass colored strongly yellow by iron, (and sometimes greenish-yellow, owing to the presence of more copper); finely-divided silica may frequently be seen in the glass, being separated from finely-disseminated slag, which is found especially in the upper layers of the Bohstein after tapping. On coal with tin in R. F. this glass becomes grayish-black on cooling, owing to anttmony; but on repeating the reduction for a longer time it becomes red from suboxide of copper. Upon mixing the residue of the roasted Bohstein with soda, borax, and a little gran- ulated test lead, and fusing it on coal in B. F., the reduced metals combine with the lead button. This is separated from the slag and treated with boracic acid on coal, until most of the lead is separated, after which it is fused beside S. Ph. on coal in O. F., and then yields a glass bead which is greenish while hot, but becomes blue on cooling (oxide of copper), and treated with tin becomes red when cold (suboxide of copper). A special assay for silver, vide quantitative assay for silver in sulphide^, will •how a little of that metal. The Eohstan therefore consists of sulphur, iron, lead, copper, zinc, {antimom/, antnie), and silver. b. Selenides and tellurides. — Lead with selenium (clausthalite), p. 223. Mercury with selenium {tiemannite), p. 263. Bismuth with tellurium (tetradymite, teUurwismuth), p. 240. c. Arsenides. — Iron with arsenic {leucopyrite),. p. 187. Oobalt with arsenic (smaltite), p. 200. Nwkel with arsenic {niccolite, rammelsbergite), p. 206. Arsenides of iron, nickel, cobalt, etc., with sulphides of copper, lead, antimony, etc. (Lead speiss/rom the Frdberg Works.) In the closed tube tarnishes black, but yields nothing volatile. In powder in the open tube yields a distinct sublimate of crystal-ine arsenoits add, which is volatile , occasionally also, near the assay, there is a white, non-volatile film, apparently a com- bination of antimonic acid with oxide of antimony, while at the upper end of the tube sulfAwous acid can be detected by the odor and with litmus paper. Alone on coal ftises in R. F. (unless there is too much iron present) to a globule and evolves arsenical fumes ; on continued blowing, however, the surfiice is covered with a crust, which becomes thicker and thicker, and after some time renders the glob- ule infusible ; a slight lead coat is also frequently perceptible. Upon ttdding sufiScient borax and treating the whole with the point of the blue flame a metallic button emerges, which emits copious fumes, while the borax glass becomes less fluid, difficultly fusible, and quite black, owing to the slagging of most of the iron. A little of this black glass with borax on platinum wire in 0. F. shows only iron. Upon then fusing the button, freed from most of the arsenide of iron, alone on coal in E. F., arsenical fumes are again evolved, but the coal is slightly coated with ojcide of lead (and sometimes antimony). By treating the button further with borax, as described in detail under the examina- tion for iron in speiases, p. 195, it is found that after the first treatment the borax still shows iron, but after the second and third cobalt, and finally fiirther fusion with borax shows only nickd. The remaining arsenide of nickel treated with S. Ph. iff O. F., however, yields a glass which is green both hot and cold, and therefore contains nickel and copper. After removing the button of arsenide and fusing the glass a moment with tin, it becomes opaque red on cooling — suboxide of copper. Should the amount of copper be too trifling to detect in this way the arsenide of nickel is fused with a button COMPOUNDS CONTAINING NO ARSENIC OR SULPHUR. 343 !of gold, weighing 50 to 80 milligr., and then slagged with S. Ph. in O. F., until a fresh portion of the salt is no longer colored yellow, but green ; the re action for copper may then be distinctly pi'oduced with tin. In this speiss may be found therefore : arsenic, sulphur, iron, nickel, cobalt, copper, lead, (antimony,) and, by a special assay, silver. E. Compounds of metals containing no arsenic or sul- phur, or but very little of either. The plan followed in examining alloys is in general the same aa for substances of the foregoing class, the roasting being, naturally, •omitted. In many oases one or other of the tests there mentioned can be omitted, when the previous behayior of the substance has fihown that no result would be attained ; on the other hand, it is sometimes necessary to make a special test for some constituent which would not be recognized during the general examination. Examples. Copper with nickel and zinc (germansilver, padc/ong). — On coal in B. F. fuses and produces a coat near the assay, yellow while hot and while on cooling. The coat moistened with cobalt solution and ignited in O. F. assumes a yellowish-green color on cooling — zinc. After being fused alone on coal the button is then treated with borax in 0. F., long enough to oxidize and dissolve all the metals, the oxides of which cannot be reduced from borax with the E. F. alone ; the button is then removed from the glass and the latter fused in E. F., until all of the reducible oxides are reduced out. It will now generally appear blue, and preserve this color when fused on platinum wire in O. F., showing only rx>balt. Fused with S. Ph. on coal in 0. F., the button freed from cobalt aifords a dark- green glass, and if a portion of this is fused with more S. Ph. on platinum wire in 0. F. it will give a fine green bead, remaining green on cooling. This bead shaken off and treated with tin on coal in R. F. becomes opaque red on cooling, from subox- ide of copper, and the green S. Ph. glass therefore showed copper and nickel. The reddish-white, malleable button, left after treatment with S. Ph., may further yield a trace of silver if cupelled with test lead. (If the button is fused with about three times its weight of gold, beside borax on coal in O. F., and kept in fnsion for some time, the glass will only show the yellow color due to oxide of nickel, because copper combined with nickel oxidizes with great difSculty in presence of much gold.) The composition of german-silver is therefore : copper, with perhaps a trace of tilver, nickel with a little c(Ut, and zinc. Raw had from the Freiberg Works. — (The same reactions will be afforded by any raw lead from ores similar to those smelted at Freiberg. Alloys which certainly con- tain no mercury, and little or no other volatile metals, need not be tested in the closed tube ; this test is therefore not made with raw lead. In the open tube it fuses and is covered with oxide, but yields nothing volatile. Fuses very easily on coal, emits a rather strong odor of arsenic, and coats the coal at first with oxide of antimony, after- ward copiously with oxide of lead. A feeble, yellowish coat is also sometimes deposited near the assay, which becomes almost white on cooling, and therefore indi- cates zinc. On fusing a bit of the lead with borax on coal in R. F., so that the borax glass is protected by the flame from access of air, a clear, colorless glass is obtained, 344 plaxtneb's blowpipe akaltsis. which generally remains colorless when re-melted on platinum wire in 0. F. If, how- ever, the lead is not quite free from iron the glass will be feebly yellow while hot. If another bit is fused on coal beside boracic acid with the blue flame, the coal is at first coated with antimony, and a distinct arsenic odor can be perceived. On continu- ing the treatment until only a small button remains, and fusing this with S. Ph. on coal in 0. F., a green glass results, which treated with tin on coal becomes opaque red on cooling — copper. By cupelling the button resulting from the treatment with S. Ph. on bone-ash with a little test lead, a small silver button is obtained. If a third bit of the lead is fused on coal in 0. F. with neutral oxalate of potassa and borax, and the fused mass, which has sunk partially into the coal, is laid on silver foil and moistened with water, it will in certain cases cause a black or brown spot of sulphide of silver, showing that sulphide of lead is sometimes present. The raw lead consists therefore of lead, silver, a little copper, arsenic, and antimony, and occasionally traces of iron, zinc, and sulphur. Black copper, very impure. The filings heated to redness in the open tube with the blowpipe flame evolved a little sulphurous acid, recognized by means of moist litmus paper inserted into the tube. At some distance from the assay an exceedingly trifling white coat was also deposited, which had the appearance of oxide of antimony. Alone on coal fused with difficulty, evolving no odor, and giving only a distinct fead loat. When fused with test lead beside boracic acid, so as to leave the metallic but ton free on one side, there was likewise no odor, but while the lead was oxidizing and dissolving in the boracic acid a white coat formed, which being scraped off and dissolved in S. Ph. on platinum wire, and the resulting bead treated ;n coal witL ^in was recognized as oxide of antimony, since the bead became quite dark gray on cool ing. The button remaining after treatment with boracic acid was found to be free from lead when tested alone on coal, and was gray and brittle. Fused with borax on coal in K. F. the black copper gave a smalt-blue glass, show ing oxide of cobalt, and this glass re-melted on platinum wire in 0. F. appeared green while hot, bat blue again on cooling — cobalt and a little iron. The metallic button remaining from the treatment with boracic acid, after a little residue of cobalt had been separated with borax, was fused on coal in 0. F. with S. Ph., giving a quite dark green glass, both hot and cold. Treated with tin tliis glass became opaque red, and the green color therefore indicated copper and nickel. The button yet remaining undissolved was likewise still gray and very brittle, and this brittleness indicated the presence of arsenic, which seemed to belong chiefly with the nickel, because it could be separated neither with boracic acid nor with S. Ph. A special tmt for arsenic, p. 303, showed the actual presence of a not entirely unimport- ant amount of that body. This black copper therefore consisted of copper, lead, nickel, cobalt, iron, antinumg, arsenic, sulphur, and, as found by a special assay, some sUver. SHver amalyam containing gold, very impure. Alone in the closed tube afibrded a sublimate of metallic drops, which were collected to a globule of mercury by gently tapping upon the tube, and could then be easily shaken out. The porous residue was first fused alone on coal, affording a trifling yellow coat of oxide of lead, while the melted silver button was covered vrith a crust. Some borax (was therefore added and the whole fused in E. F., when an apparently pure silver button with a bright surface emerged, and the borax glass was greenish on cooling. This glass treated on another part of the coal with tin assumed the pure vitriol-green color of protoxide of iron. Upon testing the remaining silver button with S. Ph. the glass assumed a grjen color (blue when cold), and, melted with tin, became opaque red on cooling — copper COMPOUNDS CONTAINIKG NO ARSENIC OR SULPHUK. 345 In order to refine the silver perfectly it was cupelled with test lead and then dissolved in nitric acid, when several black flakes remained, which on being washed with dis- tilled water and cupelled with a little test lead, formed a pure gold button. The amalgam therefore consisted chiefly ol silver and mercury, hut contained trifling admixtures of gold, copper, lead, and iron. Antimonide of silver (dyscrasite), p. 268. Platinum with other metals (native platinum), p, 273. Gold with silver {native gold), p. 278, Section III. QUANTITATIVE BLOWPIPE ASSAYS. /. Preparation of the substances to he quantita- tively examined for certain constituents. Ijsr quantitative assays with the blowpipe, just as by the wet pro- cess, the substance to be examined must undergo certain prelimi- nary operations, which are limited chiefly to drying, and, in case of mixed substances, selecting the best possible average sample. Fri- able substances containing mechanically combined water should be dried at a temperature of 100° C.,* and then pulverized in an agate mortar If the substance is brittle, but not friable, it is broken as fine as possible between paper on an anvil ; if malleable, it is beaten between paper into a thin sheet and then cut up with the scissors. Ores dressed on a large scale, even when they have not been especially dried, usually appear dry while still containing several per cent, of mechanically combined water; the same ores also absorb moisture again when kept in damp places in unclosed vessels aftei being dried. A quantity of these, more than suflBcient for two aisays, must be dried, and the dry ore pulverized in an agate mor- tar. Care must be taken to avoid too high a temperature when drying ores containing compounds of sulphur or arsenic, since otherwise, roasting, with partial decomposition of the ore and alter- ation of weight, may result. Minerals and metallurgical products, which are almost alwaye received for analysis in a dry state, are broken up between papei on an anvil, or in a steel mortar, and when friable, pulverized in an agate mortar. It is safest to prepare from the substance to be assayed eight or ten times the amount of powder needed for one assay, except in cases of pure crystals, or fragments of minerals oi metallurgical products, since, when too small a quantity is used, there is no certainty that a proper average has been attained, as regards the proportion of metal present. For example, when too small a quantity of a rich diy-stamped silrer ore, which may be a mixture of real silver ore and substances containing no silver, is taken, one may have t«o many rich portions, or too many poor portions, which will give a very different * In a watoh-glass over boiling water. 350 plattneb's blowpipe analysis. proportion of metal from that contained in the whole. From an ore prepared on ibc large scale, therefore, a quantity of at least thirty grammes shonld always be taken from various parts of the heap, mixed if possible in an iron mortar and made somewhat finer, and from this the portion required for the blowpipe assays, irom eight to ten blow- pipe centners, taken, dried according to the preceding directions, and rubbed quite fine in a mortar. II. Detailed description of the quantitative assays with the blowpipe. 1. THE SIIiVER ASSAY. The blowpipe assay for silver, first proposed by Harkort, and aescribed by him in a work that appeared in Freiberg, in the year 1837, is one of the most important assays that can be made with this instrument. It is possible not only to detect in a short time the silver in any ore, mineral, or product, but also to determine its amount quantitatively with all needful accuracy. Eegard must, however, be paid to the other substances besides silver, with which we have to do, and we must classify the mineral and metallic bodies, together with the artificial products, in order to determine the silver in them, and each of these classes must be assayed by a suitable method. They are classified into : — A. Ores, minerals, and products in which the silver is especially combined with non-metaUic bodies, and these further into : a. Those containing volatile constituents, viz., sulphur and arsenic, as well as chlorine, bromine, and iodine, in greater or less proportion, or such as are wholly free from them and can be decomposed by fusion on coal with borax and test lead. b. Those containing compounds which cannot be decomposed by fusion with borax and test lead alone. c. Those consisting of metallic oxide that are readily reduced on coal. B. Metallic compounds {alloys) ; these are: a. Those in which silver is the chief constituent, or in which gold occurs with the silver. i. In which copper or nickel forms the prevailing constituent. while silver is only a minor one. e. In which lead or bismuth is the chief constituent. d. In which tellurium, antimony, or zinc is the chief constitU' ent. ■WEIGHING AND CHARGING THE ASSAY. 351 e. In whicli tin is the chief, or else only an accessory co&stitib ent. /. In which mercury is the prevailing constituent. g. In which iron or steel is the chief constituent. A.. Assay for Silver in Ores, Minerals, and Metallurgical products is which the silver is especially combined with non-metallic bodies. 0. Substances which contain volatile constituents, viz., sulphur and arsenic, as well as chlorine, bromine, and iodine, in greater or less proportion, or are entirely free from them, and can be reduced by fusion on coal with borax and test lead. Here belong, among ores dressed on a large scale, such as contain more or less pyrites, chalcopyrite, mispichel, stibnite, and blende, as well as the minerals above mentioned ; further, all the so-called Dilrr- erze, consisting chiefly of earthy ingredients and containing only a small portion of actual silver ores ; all the ores enumerated on pages 264-266. in which the silver occurs in combination with selenium or sulphur and other selenides or sulphides, as well as with chlorine, bromine, and iodine ; further, all the copper ores enumerated on pages 246-247, in which the copper is oombined with selenium or sulphur ; the lead ores named on pages 217-218, in which the lead is present, as selenide or sulphide of lead; further, roasted argentiferous lead and copper ores, all silver ores and metallurgical products roasted, with salt, for the pui-pose of amalgamation or extraction, and the residues from amalgamation or extraction ; finally, among metallur- gical products, Rohstein, lead and copper matts, cadmia, flue dust,. lead and cobalt speisses, hearths from cupelling and refining silver,, all sorts of argentiferous slags, and also the silver scraps of the gold. and silver smiths. • 1. Weighing and Chaeging the Assat. Ores consisting of a mixture of rich silver ores and earthy parts,, which usually yield in analysis varying amounts of silver, are best weighed out in two or three portions of 1 centner = 100 milligr. {vide p. 28) each ; on the contrary, poor silver ores and crystallized minerals, as well as products which differ very little or not at all in, richness, are general!? v/eighed out only once.* The weighed portion is transferred to a mixing capsule, into wliich the scale-pan is cleaned with a brush, and borax-glass and test lead * Ores containing almost exclusively quartz are hard to fuse, and it is well to weigh out two portions ol ^ centner each, adding to each assay a spoonful of borax glass, as will be later indicated, and 1 to 9 ctr. of test lead. 353 plattnek's dlowpipe axalysis. are then added. The quantity of borax-glass is regulated by the fusibility and amount of the substances to be converted into slag The small spoon, Fig. 56, heaped full and containing about one decigr. or one ctr. of borax-glass is suflBcient for an assay of diflBcult fusion, bul if during the fusion the assay seems too refractory, a small portion of this flux can be added. Less is needed with very fusible ores, oi in general, such as hare no earthy admixture, but consist only of metallic sulphides which combine readily with the lead and are less oxidizable than it. For these a spoon but slightly heaped, contain- ing from one-half to three-quarters ctr., is quite suflBcient. With assays containing a considerable proportion of earthy ingredients, oi much iron, cobalt, or tin, the spoon must always be heaped full. The quantity of test lead is regulated by the presence of othei metals in the assay substance. If it is a substance containing not more than seven per cent of copper or ten per cent, of nickel, five ctrs. of lead are used for one ctr. of assay powder, being measured in the test lead measure. Fig. 58 ; if the substance contains more than seven per cent, of copper or ten per cent, of nickel, the amount of lead must be proportionally increased. The presence of cobalt is less to be regarded, as this metal is easily slagged off with borax. As we cannot always know beforehand how large an amount of these metals is present, it is better to use too much lead than too little, since with too little lead the separation of the copper from the silver is not thorough, while the cupellation of lead rich in nickel is almost impossible. The following minerals and products, containing partly copper and partly nickel, must therefore be charged with the indicated amounts of test lead : — I ctr. Chalcocite, cont^ning about 80 % Copper, with 15 ctr. test lesi. (( Covellite ti 65—66 ■■ " " 12 " Bomite (( 55—60 " " 12 " Tetrahedrite " 30—40 " " 1 " Chalcopyrite " 30—34 •' " .. 10 " StForaeyerita " 30-31 " .. \ " Stannite (C 29—30 " : :\^ " Bouraonite " 12—13 " M Copper Matt II 30—50 " '• 10 it U 11 H 50—70 " " 12 tt Iiead speisa II 10—40 " Nickel, Co- bait, and Copper " 10 1 II Cobalt speiss with 40—50 " Nickel and Cobalt " Ifl When the substances have been most thoroughly mingled in the mixing spoon, with the aid of the ivory spoon handle, the charge is poured into a soda-paper cylinder, made as directed on p. 42. For FUSIOK OF THE ASSAY. 353 this purpose the cylinder is held between the thumb and index finger of the left hand and the mixing spoon with the same fingers of the right hand, while the closed end of the cylinder rests on the middle finger of the left hand. The lip of the capsule is then inserted into the paper cylinder, which is slightly inclined to one side, as far as seems necessary for safely pouring in the charge, the paper being pressed against the lip with the finger and thumb, so that the capsule cannot fall on removing the right hand. The charge is then caused to slide gradually into the cylinder by gently tapping on the outside of the capsule with the brass forceps, and any adhering dust is brushed into the paper. While the lower end of the cylinder still remains resting upon the middle finger of the left hand the upper empty end is pressed out flat and then rolled up from the top downward ; the cylinder thus far closed is placed with the lower end on the extremity of the left thumb, and the ends of the part that was rolled together are bent upward and toward each other, making the whole perfectly tight. While wrapping up the charge care must be taken that the lower end of the cylinder does not open or the paper tear in any part, thus occasioning mechanical loss. 2. The Fusion of the Assay. The fusion of a silver assay is performed on coal with the blow- pipe flame.* In the cross section of a good piece of charcoal, near one corner, a deep cylindrical hole is bored with the square borer. Pig. 46, the diameter of which is about one-third more than that of the paper cylinder ; or a coal crucible. Fig. 17, is used, as shown in Fig. 78, A. The latter mast also be bored out as deep as necessary, and the hole widened from above with the knife, so that the flame can be directed between the assay and the inside of the crucible down to the bottom, and the assay thus readily melted. The cylinder is set in the cavity with the end last closed above, and is pressed down firmly. The assay is now inclined toward the flame, and a pure, but at first not too violent, reducing flame directed upon it, so that it almost covers the upper part of the paper cylinder. The soda-paper is indeed charred in " ^"-w moments, but the ashea * Quantitative blowpipe assays require a continued and powerful blast, so that a bellows blast is to be recommended, especially in roasting copper ores, and in making assays in crucible, as for lead, bismuth, tin, cobalt, and nickel. 354 plattnee's blowpipe axalysis. are not disturbed until the borax-glass nas already fused together i he separate particles of ore, so that they cannot be blown away. When the ashes of the paper burn away, exposing a part of the charge as a fluid slag, mixed with melted globules of lead, the whole assay is covered with a strong, but pure, reducing flame, which has an in- clination of 30° to 35°, as shown in Fig, 78. During the time that this flame is used, portions of the sulphur, arsenic, antimony, zinc, etc., volatilize, but the greater part of them, as well as several of the metals still combined with sulphur and arsenic, join with the lead and melt with it to a button. The earthy ingredients, on the other hand, and the metallic oxides of diflBcult reduction, with a small part of the non-volatile and easily oxidizable metals, which become in part oxidized by the first action of the heat, fuse with the borax to a slag. With compounds of silver and chlo- rine, bromine, or iodine, which are decomposed by the lead, vapors of chloride, bromide, and iodide of lead are seen to pass off. Although it generally seems, after a short time, as if the slag was quite free from lead globules, this must not be regarded as satisfac- tory, since beneath the well-fused slag there are often unmelted por- tions of the charge, which can only be affected by the blowpipe flame when this is directed between the slag and coal against tlie bottom of the crucible, while the charcoal, or the clay cylinder with the crucible, is turned during the blast and held inclined toward another side, until the assay has changed its position and turned over. In this turning over, which should take place even with the most fusible assays, the bottom of the paper cylinder, being all that remains of it, rises from below, and comes in a charred state to the top, or to one side. To destroy the ashes of the paper the assay must then be so held toward the flame that only that part of the slag where there is no paper is covered by it, when the air instantly rushes in and the ashes are consumed. When the position of the slag c, which has been covered with the reducing flame ab, Fig. 78, has been altered several times with regard to the lead button d, and the slag finally appears quite fluid and free from lead globules, it is also certainly free from silver. The E. F. is changed to a moderate 0. F., which is directed against the lead only, and at a somewhat greater distance. The above-named volatile metals, with the sul- phur, are now driven from the lead, while some of the easily oxidiza- ble metals, as iron, tin, and cobalt, with a small part of the nickel and copper, are oxidized and combine in this state with the slag ; only the silver, with the gi-eater part of the copper and nickel, remains with the lead. In substances containing much arsenide FUSION OP THE ASSAY. 353 of nickel it~is diflBcult to destroy this combination, which does not combine readily with the lead, but remains on top of it, and must be treated a long time with the 0. F. to oxidize and slag off all the nickel and arsenic. Since, however, this compound readily yields its silver to the lead, no loss of silver need be feared, even if the arsenide of nickel is by no means entirely decomposed, and in many cases it may even be mechanically separated from the lead with advantage after the assay has cooled. When the volatile parts of the assay are nearly gone, a part of the lead is oxidized, and with it a trace of the silver, which is, however, very trifling. Both oxides are taken up by the slag, but as this is always in contact with the coal, a portion of the dissolved oxide of lead, exceedingly poor in silver, is reduced at the points of contact, occasioning a bubbling in the slag. The slag has now lost its spheri- cal shape and has spread out, and the reduced globules of lead, first appearing on its borders, are gradually carried toward the argen- tiferous lead button by the motion of the slag, and unite with it. When the volatile matters are quite gone, the lead button begins to oxidize more rapidly and assumes a rotary motion, while the bub- bling in the slag is livelier. On observing these signs the coal is inclined a little, so that the lead button may go to one side in case it is quite surrounded by slag, the blast is stopped, and the assay allowed to cool upon the inclined coal. When there are few or no constituents that require to be volatilized by an oxidizing blast, a short treatment only with the O, F. is needed, after the fusion of the silver particles with the lead and the conversion into slag of the earthy portions and the metallic oxides of diflBcult reduction. The fusion may be regarded as completed if, after the assay is cold, the argentiferous lead or silver-lead, has a white color ; if, however, it appears black, this depends, in. case of a substance free from cop- per, upon some sulphur or antimony remaining in it ; with a sub- stance containing copper, on the other hand, either upon the copper alone, or upon this and both of the others at the same time. Sul- phur and antimony can be removed in 'both cases by treating the assay again with the 0. F., but the copper can only be separated together with the lead during the cupellation. In assaying any sub- stance for silver, therefore, a white lead cannot be expected if more than a trifling amount of copper is present, and we .can only assume that the sulphur is all removed when the lead has been in rather strong rotary motion for at least one minute. The complete removal of volatile bodies from the lead by an oxidizing fusion is necessary for two reasons ; first, because the impure lead is generally brittle, 356 plattnek's blowpipe analysis. and some of it may easily be lost in breaking off the slag and, secondly, because it is liable to sputter on the cupel, especially when containing sulphur. When the assay is cold, the slag and lead are lifted out jf the crucible with a knife, laid on an anyil, and the slag separated as much as possible with a few strokes of the hammer, after which the lead is held with the forceps and beaten into a cube. Should a small button of arsenide of nickel adhere to the lead from an assay rich in nickel, as mentioned above, an attempt must be made to separate it here, that it may not impede the cupellation. Among the ores, minerals, and products to be fused according to the preceding method, the most infusible are pyrites, mispickel, cer- tain nickel and cobalt ores, and such Rohsteins as consist chiefly of sulphide of iron ; the other substances in this class fuse, for the most part, very easily, even when mixed with refractory earthy matters. No right result would be obtained if, as beginners frequently do, the attempt were made to perform the fusion of a silver assay with the 0. F., since a considerable amount of lead would be oxidized at the very beginning, the oxide would dissolve in the borax, and being reduced by the coal, would form fresh globules of lead, which would abstract a portion of the silver still remaining in the slag. On attempting, after a few moments, to collect these separated globules by varying the position of the chief button in the slag, which would have spread out to a great extent over the coal, new ones would con- stantly form in their place, which could not be distinguished from those containing silver. The spreading of the slag also renders the complete fusion of the charge at the bottom of the crucible difficult or quite impossible, and an assay in which this mistake has been committed should be regarded as useless. [The utmost care must be taken to blow a reducing flame only, during the first part of the fiision ; then the lead cannot oxidize, the borax and dissolved bodies will retain a spherical form and not adhere to the coal, the assay can, at the proper time, easily be made to turn over and expose the lower part of the paper and charge, and then, when all is in proper fusion, the oxidizing flame ia to be used so as to drive off the sulphur, etc. While the flame must be reducing at first, it must still be large enough to keep the whole mass at a proper temperature, and it must be borne in mind that the heat produced is nearly as essential to success as the quality of the flame. Transl.] The time required for the above fiision depends upon the assay to be treated. If it contains a large amount of volatile substances, or such as must be slagged ofij eight to ten minutes are necessary ; if but little, about five minutes. When several assays are to be made the second can be fused while the first is cooling ; then the third is taken up, and so on, until all the assays weighed out have been fused. The assays must be arranged according to their number, to avoid confusion. When the several assays have been fused the first ones will be cold and can then be freed from slag in their proper order. When but one assay is to be made, the cnpel tir it can b« formed, as will be described nnder cupellation, while the silver-lead is coolie g. euoKiFiCATiou. 357 3, cupellation op the silver-lead obtained by the Fusion. It is well known that the cupellation of the silver-lead is an oxid- ation occurring at a red-heat with access of air, by which the lead with other oxidizable metals is separated from the silver, whicli oxidizes with difficulty. In the blowpipe assay this oxidizing or cupelling process is divided into two periods, viz., the Haupttreihen, the chief cupellation, or, as we will style it, the scorification, and the Feintreiben, or refining cupellation, which we will call the fine- cupellation. This division is necessary because it is not possible to separate a large quantity of lead from the silver in one period, so that the latter may remain in the form of a pure round button, as in the muffle assay. We will, therefore, now describe the first period, or THE SCORIFICATION. This is the easiest operation in the whole silver assay. A cupel of sifted bone-ash, p. 25, is struck in the cupel mould. Fig. 49, A, placed on the stand. Fig. 50, and the bone-ash heated with the 0. F. in all parts as strongly as possible, so as to remove any remain- ing hygroscopic moisture. If this heating is omitted, the steam escaping during the fusion is liable to cause the lead to sputter and be lost. After heating the cupel, the lead is placed in the middle of it with the forceps, and brought into fusion with a rather strong 0. F., so that the oxidation of the rotating lead begins. During this operation the cupel is inclined slightly backward from the lamp, and the result is efiected most rapidly by allowing the point of the blue flame to act directly on the lead. When the lead contains much copper or nickel the period of fusion, before the oxidation begins, is somewhat prolonged, since the copper makes the lead less fusible, while the nickel separates as the lead begins to oxidize, covering the whole surface with an infusible coat, and causing a difficult cupellation, or, with too little lead, entirely preventing the operation. In the latter case, a piece of pure lead of from two to four ctr., ac- cording to the thickness of the crust, must be added to the silver- lead in the cupel, and then only is the cupellation possible. Persons not accustomed to using the blowpipe sometimes expe- rience inconvenience in not immediately causing a large button of silver-lead to oxidize, or else it freezes during the process, becoming covered with a coat of oxidized lead which they cannot easily drive 558 i-LATTNEE'S BLOWPIPE AKALISIS. away. In this case a somewhat stronger blast must be used, and the lead touched directly with the point of the blue flame, and after this has acted uninterruptedly on one point of the lead button, the lead will soon begin to oxidize again. When the lead has been brought to the proper temperature for cupellation, the tip of the blow- pipe is thrust farther into the flame, so as to produce a fine blue point, a, Fig. 79, which is directed at an angle of about 30° upon the ox- idizing lead, so that this is kept at a moderate red heat, but is only touched by the outer flame, and on no account by the blue flame. The surrounding air thus has free access, while the lead (and copper) absorb a portion of the oxygen from it and become oxidized. The oxide formed flows from the upper surface of the lead to the border, exhibiting prismatic colors caused by the interference of light, and solidifies on the cupel behind the button to a firm mass called litharge. Fig. 79, c, which has a reddish yellow fracture after cooling, if free from other oxides. When the lead contains Tery much silver the prismatic colors are less distinct, and thus a large proportion of silver is already indicated ; if it contains copper, the color of the solid litharge is nearly black. The cupellation must proceed at neither too high nor too low a temperature. If it is too hot the lead begins to vaporize, and some silver may easily be mechanically carried off, especially if the lead is rich in silver ; moreover, the litharge does not cool upon the cupel, but sinks into it, by which again a part of the silver is lost, since the surface of the lead is covered with too little fused oxide of lead, and the silver has a chance to become oxidized. If the cupel- lation is carried on too "cold," and the temperature is not high enough to continue the oxidation of the lead, the latter becomes covered with too much litharge, the motion of its surface ceases, and 'it freezes. This mistake is less injurious than having too high a temperature, since the frozen assay can be immediately made to oxidize again by a somewhat stronger flame, without loss of silver ; but this must not occur often in the same assay. When the scorification proceeds at the proper heat, which cannot be so clearly described as perceived by practice, the litharge collects around and chiefly behind the lead, and solidifles. After a quantity jf it has collected, and the lead in its midst has too little surface exposed, the cupel is gradually brought into another position with- EINE-CGPELLATIOH'. 353 out interrupting the operation, so that the lead, by reason of its weight, may move to the side of the litharge and expose a greater surface for oxidation. The lead having finally decreased so much that, in an» assay not very rich in silver, it is only the size of a mustard-seed. Pig. 79, d, and in case of a rich assay, about two or three times as large, the cupel is removed from the flame by degrees, so that the lead button may very gradually solidify in the litharge. The button will indeed always be somewhat raised by the contrac- tion of the cooling litharge, but if too hastily drawn away from the flame, the still soft button will be too violently driven out by the solidification of the litharge, and a spattering of the lead, with loss of silver, may easily occur. Notice must here be taken of a phenomenon which sometimes appears at the close of the scorification of a lead button very rich in silver. When such lead has been so far oxidized that it consists of about six or seven parts of silver to one part of lead, and allowed to cool slowly in the litharge before a gradually diminishing blowpipe flame, a grayish-white, easily friable mass is forced out from the^ solidifying lead, which is always very rich in silver. It appears to be a sub-oxide of lead mixed vrith metallic silver, and is probably to be regarded as a phenomenon allied to the sprouting of silver, which will be mentioned under the flne-cupellation. If unnoticed, the greater part of this mass falls off in separating the lead from the litharge, entailing a not altogether unimpor- tant loss of silver. This evil can be remedied by treating the silver button containing lead immediately on the cupel with the E. F., or fusing with it a small piece of test lead, when the whole unites into a button, which cools with a clean surface. It, therefore, rich ores or products are to be assayed, it is always well not to continue the soorifloatiou too long. After the scorification, the lead button, which is in, or surrounded by, the litharge, is taken out together with it, and when cool is freed from all adhering litharge, which is very easily done by laying the whole on an anvil and pressing off the fragile litharge from around the button with the broad face of the hammer, without touching the button; any remaining litharge may then be removed by a few strokes of the hammer. THE FINE-CUPELLATION. This requires more care and practice than the preceding operation. The bone-ash remaining from the scorification which is not per- meated by oxide of lead is broken up with the small iron spatula, covered over with enough elutriated bone-ash to fill the cupel mould, and after placing on it the proper stamp, it is struck with a few blows of the hammer into a cupel for the fine-cupellation. This ia then thoroughly heated as before, and if any cracks form, or por- 300 plattker's blowpipe analysis. tions of the bone-ash become loosened during the heating, from moisture remaining in the bone-ash, the fault can be at once reme- died by placing the clean stamp upon it and striking it once or twicft gently. For this purpose the mould must of course be removed from the stand to the anvil. The lead button, d, Fig. 79, is then placed with the forceps upon the cupel, so that it may lie nearer the left-hand edge than the mid- Pdle, Fig. 80, that any adhering substance may re- ^^ main at the edge when the button moves toward . ^m. the middle, and may not prevent the formation of a spherical silver button during the fine-cupella- tion. The cupellation is then carried on, observ- ing the following directions. First, the cupel is brought near the lamp flame, with the stand so much inclined in an opposite direction, that the lead button, which is on the further side, cannot roll down before it has become fused. The button is then heated with the 0. F., directed downward as much as pos- sible, until it fuses and begins to oxidize. As soon as this takes place, the stand is gradually brought into a vertical position and the flame ab directed at an angle of 40° to 45° upon the cupel, toward the middle of which the button is moving, so as to heat the bone- ash directly about the button and keep it as much as possible in a constant glow around it. This is best effected by moving the cupel slowly around in a small circle before the blowpipe flame, the direction of which remains unaltered, at the same time inclining the stand as required toward the flame, and giving it, if necessary, a slight rotary motion. Without touching the assay with the flame, a strong enough heat must be imparted to the bone-ash to keep the assay in oxidation without allowing it to become quiet, or to freeze. Should this happen, the solidified lead must be brought for a moment nearer the flame, so as to cause it to oxidize, and the cupel then immediately moved slowly about in a circle before the flame again. The cupellation proceeds better, the drier the surface of the bone-ash; that is, the more perfectly the litharge sinks into it. If the bone-ash is not strongly enough heated it becomes covered with a thin coat of litharge, in which the button begins to swim about rapidly, and even if this does not ruin the assay it is still very difficult to detach the silver button from the cupel, and thus an uncertain result is caused. It is not indispensable, and in case a large amount of lead remains with the silver m t possibl?, to complete the fine-cupellation on one FINE-CUPELLATIOK. 361 spot of the cupel, but the button may just as well be allowed to roll from one place to another, only keeping the bone-ash around the button at a red heat without touching the latter with the flame.. When the last portions of lead have been oxidized from a lead but- ton poor in silver, the rotary motion of the remaining silver button may cease without a change of color; the heat is then raised to remove entirely the last thin coating of litharge, which separates with the most difBculty, and the silver button is allowed to cool slowly by gradually removing it from the flame. It can be exam- ined with the glass, to see whether it has the pure silver color, with a bright snrfece, or whether it requires further heating. If the lead is rich in silver a play of color is seen about five or ten seconds before the "brightening" of the pure silver, while the last portion of lead is separating as litharge. Colors appear, similar to those in the scorification, but they are much finer, on account of the thinner coating of litharge which reflects better and causes more perfect interference of the light. They also vanish entirely as soon as the silver is pure. So long as the fine prismatic colors appear the cupel should b& moved about in a circle before the oxidizing flame, so that the metal- lic button is nearly touched by the tip of the blue flame and is driven from one point to another, while the blast must not cease until the surface of the silver is quite free from litharge, which can be very well seen with a rich assay. As soon, however, as it shows a clean surface the assay must be very gradually removed from the flame and the silver allowed to cool slowly. When a large silver button is heated for some time after it has brightened, some silver may easily volatilize, as can be seen from the rose-colored coat that forms on the cupel ; moreover, here and there on the bright surface of the fluid silver button dull spots appear near each other, having the appearance of foreign substances, which finally form a crust, and have a dull silver-white color when the button is cold.* The silver button must be slowly cooled to prevent the so-called sprouting, a phenomenon due to the absorption by the silver of a small amount of oxygen during the cupellation, and this escaping again at the moment of solidification may easily cause some loss. In cupelling silver-lead containing such a quantity of copper that it cannot be completely oxidized at the same time with the lead, the silver button generally spreads out during the brightening, and * These appear to be a combination of silver and oxide of silver, and may probablj; be regarded as over-refined silver, analogous to over-refined copper. 363 PLATTIfEE'S BLOWPIPE AlfALYSIS. althougli it appears white after cooling, is often anything but frea from copper. Such a button must be melted immediately, while still on the cupel, with one centner of fused test lead, or if so small as to require measuring on the scale, with one-fourth to one-half ctr., and cupelled fine on another part of the cupel, so that it may become round and quite pure. It is better to perform the final cupellation of a very cupriferous lead in this way than to add at the start as much lead as is necessary for the perfect separation of the copper, since in many cases almost twice as much test lead would then be required and the fusion and cupellation would be rendered more difficult. Slight obstacles sometimes arise in the fine-cupcUation of the silver-lead, which if disregarded may exercise a very bad influence in determining the weight of the silver button on the measuring scale. 1 . In spite of all care a bit of bone-ash or something else may adhere to the lead, and if the operation were continued without regard to this there would be danger of the silver button adhering to it, or, if very small, getting under it, and it would in any case receive a very irregular shape. It is then better to interrupt the cupellation. Lay a little piece of fused test lead near the button and melt the two together, after which they are again cupelled. By this means the mass of lead is increased, and when tho n is so small that its weight can be better determined on the scale than the balance, it must be carefully detached from the cupel with the small brass forceps, p. 3C, so that it may retain its shape, while as little bone- ash as possible adheres to it. If too strongly pressed its diameter WEIGHT OF SILVEK BUTTONS. 363 will be altered, and if any bone-ash adheres to it, the button cannot be accurately measured when placed on its flat side. The best method of proceeding is as follows : First place the cupel mould upon the anvil, then carefully insert the shai-p end of the small iron spatula, or the point of a small knife, between the button and the bone-ash and detach it from the cupel, holding it meanwhile with the small forceps, after which it is cleaned by rolling it between paper underneath the finger on the table, and placed upon the scale. The mode of operating in measuring such a button, or determining the amount of silver generally, on the scale, has been already given under the description of the scale on p. 28, et scq.* The liability of silver to oxidize causes a loss, called the cupellation loss, in cupelling argentiferous lead in the muffle. The same loss occurs in the blow- pipe assay, not only in the fine-cupellation, where the litharge sinks into the bone-ash, but also in a less degree during the scorification and during the fusion of the ore, while the assay is subjected to the 0. F. It is, however, less than that which occurs in the muffle assay, where all the litharge formed in cupelling the lead must sink into the mass of the cupel. With only one per cent, of silver this loss is scarcely perceptible on the balajice, but it becomes appreciable as the button to be weighed grows larger, and if reckoned by percentage it increases again as the button becomes smaller ; it also alters as the quantity of lead to be cupelled increases or diminishes, but remains constant in other respects, for each separate proportion of silver, if thB same quantity of lead is always used and the proper temperature employed in the cupellation. Plattner has sought by careful experiments to ascertain the loss that occurs, with a proper temperature for the cupellation, for every weighable amount of silver down to one per cent., with varying quantities of lead. The tabular arrangement of the values found is given on pp. 364-365. Since, according to p. 352, cupriferous silver ores and minerals are charged with 5, 7, 10, 13, and 15ctrs. test lead, according to the amount of copper they contain, while the silver button obtained by their cupellation can only be completely refined by adding one more centner of test lead, their cupellation loss is given at once for the whole amount of lead, viz., 6, 8, 11, 13, and 16 ctrs. If the blowpipe balance described on p. 26 is so delicate as to * Goldsohmidt (Zeltschr. f. analyt. Ch. vol. 16, p. 43i et seg.) has proposed tc determine the weight o£ small silver and gold buttons with the microscope, the advantage of tho method being attested by nnraerous careful experiments. [If the button is too small to remove from the cupel (less than 0.03 mgrm.) a fair result can be obtained by placing the cupel itself under the microscope. Transl.] 364 plaxtkeb's blowpipe analysis. TA Showing the Loss which occties in CuPELLma The assay contains the following amounts of Weight of 80 to 99 v.. 60 to 79 v.. 30 to 59 %. 10 to 29 •/,. THE SILVEB BUTTON OBTAINED BT And has been charged and cnpelled CUPBLLATION. 16ctis.lead. ISctrs. lead. 11 ctrs. lead. 8 ctrs. lead. The cupellatioh loss suflTered hj th« MiUigrammes. MUligr. MilUgr. Milligr. Milligr. 99.5 to 99.75 90. 0.83 m. 075 70 0.82 0.6S 60 0.74 0.61 5a 0.65 0.54 40 0.62 0.55 0.46 35 0.57 0.50 0.42 30 0.51 0.45 0.38 25. 0.45 0.40 0.34 20. 0.45 0.39 0.35 0.29 IS. 0.37 0.32 0.28 0.23 12. 0.32 0.26 0.23 0.19 10. 0.27 0.23 0.20 0.17 9. 0.25 0.21 0.18 0.16 8. 0.22 O.IS 0.16 0.15 7. 0.20 016 0.14 0.13 6. 0.17 0.14 0.12 0.11 5. 0.14 0.12 0.11 0.10 4. 0.11 0.10 0.09 0.08 3. 0.09 0.08 0.07 0.06 8. 0.07 0.06 0.05 0.04 1. 0.05 1 0.04 0.04 0.03 indicate 0.05 milligr., the cupellation loss can be reckoned with both decimal places, and for silver buttons weighing between 70 and 60, or 50 and 60, etc., milligr., it can be reckoned from the difference. When the balance will only indicate 0.1 milligr. with diflBculty, it is unnecessary to reckon the cupellation loss with more than one decimal figure.* * Beginners, lacking the necessary practice, are apt to cupel too hot, and may still get too low a value, even after reckoning in the cupellation loss, as given in the tables. WEIGHT OF SILVER BUTTONS. 365 BLE SiLVEE WITH VABIOVB AMOUNTS OF TeST LeAS. copper : THE ASBAT CONTAININQ SO COPPER, OB LESS THAJI 7 to 9 v.. 7 Vi, HAS BEEN CHARGED AND CUPELLED WITH with: 6 ctrs. lead. S Ctrs. 4 Ctrs. 3 ctra. 2ctra. Ictr. silver present in the assay is : Milligr. MiUigr. Milligr. Milligr. Milligr. Milligr. 0.50 0.45 0.39 0.32 0.25 0.69 0.47 0.42 0.36 0.29 0.22 0.64 0.44 0.39 0.33 0.26 0.20 0.58 0.40 0.35 0.29 0.23 0.18 0.52 0.36 0.30 0.26 0.20 0.16 0.46 0.32 0.26 0.23 0.17 0.14 0.39 0.27 0.22 0.20 0.15 0.12 0.36 0.25 0.20 0.18 0.13 0.11 0.32 0.22 0.18 0.16 0.12 0.10 0.29 0.20 0.16 0.14 0.10 0.25 0.17 0.14 0.12 KTO. 0.20 0.15 0.12 0.10 BTO. 0.17 0.13 0.11 0.15 0.11 0.10 ETC. 0.14 0.10 0.13 0.09 ETC. 0.12 0.08 0.10 0.07 0.09 0.06 0.07 0.03 0.05 0.04 0.04 0.03 0.03 0.02 In order to learn by practice the temperature to be used in cupelling, particularly in the fine-cupellation, an accurately weighed button of pure silver is fused with five ctrs. of test lead, under a cover of borax-glass in the B. F., and after cupelling the silver-lead thus formed the pure silver button is weighed again. If the loss is greater than that given in the table for a button of this weight, it has been cupelled too hot, provided there has been no mechanical loss ; if it is not greater, the proper heat was employed ' Generally the greatest loss occurs in the fine-cupellation. 366 plattser's blowpipe analysis. Naturally the cnpellation loss is only to be added for assays thai do not serve as a control on commercial assays of ores ; moreover, in blowpipe assays, where the silver must be measured on the scale, tne loss is not reckoned in, because the proportion of silver is so trifling that the cupellation loss is often less than the error that may occur in the measurement itself. Should the amount of silver in the substance to be assayed be so small that it comes among the lowest lines of the scale, it is safer for an unskillful person to weigh out several centners of the prepared assay powder, charge them each with the necessary amount of borax and test lead, fuse the prepared assay according to the method pre- viously described, and then scorify the pieces of silver-lead so obtained by twos, or threes, at a time, down to small buttons. These small buttons, in which the amount of silver is already considerably con- centrated, are then scorified all together on a fresh cupel, and the resulting button is cupelled fine. In this way the silver is united to one large button, the weight of which, as given on the scale, need only be divided by the number of centners weighed out to find the amount in one centner. It is assumed, however, in such a concentration assay, that the test lead is quite free from silver; otherwise the amount of silver in the quan- tity used must be determined by concentrating an equal amount, cupelling it, and deducting the silver found from the result previously obtained. b. Assay of minerals containing compounds which cannot be decom- posed by fusion with borax and test lead alone on coal. Molybdenite is such a mineral, and an argentiferous specimen of this from the Zwitter of the Altenberg tin stocJcwerTc in Saxony contained, according to Plattner, 0.176 V. silver. This mineral is neither decomposed nor dissolved by borax, but is decomposed very easily with eflfervescence by soda, and regard must be had to this behavior in the fusion of the assay. A small quantity of the molyb- denite is first broken up as much as possible in the steel mortar, or- Detween paper, if it cannot be pulverized in the agate mortar, ana then 1 ctr. is weighed out and mixed with 1\ ctrs. soda, 1| " borax-glass, and 5 « test lead. This charge is wrapped up and fused like any other assay. The' molybdenite is decomposed by the soda, its sulphur combining with. ASSAY OF METALLURGICAL PKODUCTS 367 the radical of the soda to form sulphide of sodium, while the liber- ated molybdenum partly combines with the test lead and partly volatilizes, coating the coal white. When the slag flows quietly, and there are no more scales of molybdenite to be seen, the lead button, which generally lies under the slag, is caused to come out by inclin- ing the coal or crucible, and is treated with the 0. F., until all the molybdenum, which forms an almost white and somewhat brittle alloy with the lead, is volatilized, and then the assay is allowed to cool. The addition of borax is necessary to prevent the sulphide of sodium from spreading over the coal. The lead is cupelled as before described. c. Assay of metallurgical products which consist of metallic oxides and are easily reduced on coal. Litharge and dbstrich belong here. When resulting from the smelting of argentiferous lead ores they always contain silver, even though in very small quantities, probably present as oxide. They are, however, generally so poor in silver that the amount cannot always be exactly determined from one blowpipe assay centner ; but as they mostly consist of oxide of lead alone, which is very easily reduced, a large quantity can be taken, and the determination of the silver is free from diflSculty. Five ctrs. of each of these products is weighed out in the form of powder, mixed with an even spoonful of soda and the same amount of borax-glass, and the charge, wrapped in soda-paper, is treated in a cavity in good charcoal, or in a properly cut coal crucible, with the E. F., until all the oxide is reduced and the slag lies beside it, as a spherical bead, free from lead globules. Toward the end, however, the flame must be directed rather on the slag than on the reduced lead, otherwise a violent movement of the lead would ensue, with a possible loss of silver. The lead reduced from litharge sometimes contains traces of copper, but is generally free from volatile metals, while that from abstrich often contains, besides a little copper, some antimony, arsenic, zinc, etc. These ingredients separate when, after ending tlie fusion, the slag alone; by the side of the lead, is treated witli the K. F. The silvci-lead is cupelled as in any other assay. 368 plattneb's blowpipe analysis. B. Metallic Compounds. a. In which the silver is a chief ingredient. Here are to be classed : native silver, brightened, cement, refined, retort, a.ndi jewellers' silver, and silver coins. No regular fusion of the substances is necessary, but they must be melted together with test lead, in order to separate by cupellation, together with the lead, the easily oxidizable metals that are mixed with the silver. As these substances cannot be readily pulverized, it is unnecessary to weigh out exactly 100 milligr. for an assay, but a piece can be chiselled or broken off, which weighs from 80-100 milligr., but not more. If the surface is not clean, it must be made so by filing, before breaking it up. Of the richer substances 50 to CO milligr. is enough. The clean fragment is accurately weighed, placed in a hole made in charcoal with the borer. Fig. 46, or in a coal crucible, and covered with one ctr. test lead and half a spoonful of borax-glass, if it is native silver, brightened, cement, or fine silver ; but if it is a cuprif- erous retort or refined silver, or other silver alloyed with copper, it must be mixed, according to the proportion of copper, with two to seven ctr. lead and half a spoonful of borax-glass. The fusion is made with the R. ¥., and the test lead soon unites with the metallic compound and acquires a rotary motion. The union of the separate metals may be considered perfect when this has lasted a few moments; the blast is stopped, the whole allowed to cool, the fused assay raised from the coal, and the borax-glass separated as car'^fuUy as possible from the lead with a few strokes of the hammer. Although the lead can be easily combined with silver, copper, and many other metals by the blowpipe flame on coal without adding borax-glass, some of it readily oxidizes when it acquires a rotary motion, and the oxide formed being immediately reduced again on coming into contact with the coal, produces such a violent com- motion in the fluid metals that spattering may easily occur. If, however, a little borax-glass is added and treated uninterruptedly with the R. F., the lead fuses easily with the metallic compound, and assumes the rotary motion without the occurrence of the evil mentioned. The silver-lead is cupelled as before described. Compounds which have been fused with but one ctr. of lead can be subjected at once to fine-cupellation, but this is less to be recommended with a greater METALLIC COMPOUlfDS. 36D amount of lead, and at all events only for a practiced person. 1b this case the oxidizing lead button, rich in silver, is caused to move away from the litharge to a free spot on the bone-ash, by slightly inclining the cupel, and is here cupelled to fine silver without letting it come in contact with the heaped up litharge. Should the metal- lic compound contain several per cent, of copper, opportunity for oxidation must be afforded to this metal .as much as possible during the scoriflcation, so that in the fine-cupellation the rest of the cop- per may be separated by adding only one ctr. of test lead, according to p. 362. When, therefore, a rich lead, containing a considerable quantity of copper, is to be treated, the oxidizing lead must not be surrounded by too much litharge in the scoriflcation, but the cupel must be con- stantly held in a somewhat inclined position, so that the surface of the lead may be as free as possible and the copper may have suffi- cient opportunity to oxidize also. 'When the silver compound con- tains gold, the amount of this is determined by the process given under the gold assay, and deducted from the weight of the silver. h. Assay of metallic compounds in tuldcli copper or nicTcel forms the chief, and silver only a minor ingredient. Here are to be reckoned : hlack copper, raw copper, refined copper ; also, argentiferous copper coins, brass, German silver, etc. A small quantity must be prepared from a clean surface of the substance, by beating it out and cutting it with the scissors, or by filing, so that an assay may be easily weighed out. In the case of black copper, raw copper, refined copper, argentiferous copper coins, and German silver, one ctr. is charged with twenty ctrs. test lead, or, to avoid so large a volume, one-half ctr. of the compound witli 10 ctrs. test lead and ^ ctr., or one even spoonful, of borax-glass. This is well mixed in the mixing capsule, wrapped in soda paper, and fused in the R. P. as already described. The lead with the com- bined metallic compound must remain for some time in rotary motion, until no more of the metallic particles, which at first generally float upon the lead, can be seen. If the fusion were broken off earlier, those portions of the metallic compound not yet thoroughly combined with the lead would pass in part mechanically into the litharge during the subsequent cupellation. During iho 370 plattner's blowpipe analysis. fusion any cobalt and iron, sometimes present in German silver, are oxidized and dissolved in the borax -glass, but the zinc, which is a chief ingredient of German silver, is volatilized. The lead after cooling is separated from the slag on the anvil and cupejled as before, but the button of silver obtained by the fine-cupellation generally spreads out, owing to the presence of copper, and it must be subjected to a second refining cupellation on the same cupel, with one-quarter to one-half ctr. of melted test lead, as directed on p. 363, £0 that the button may have a proper diameter for the determination of the silver on the scale. The weight of the silver button must necessarily be doubled if only one-half ctr. of the substance was taken for the assay, and in order to be safe with such an assay, two portions of one-half ctr. each may be weighed out, and the argen- tiferous lead buttons obtained by the scorification united in the fine-cupellation. To assay brass for silver, 1 ctr. is charged with 10 ctrs. test lead and 1 heaped spoonful of borax-glass. The charge, wrapped in soda-paper, is treated as before in the K. F., until the lead has united with the metal to be assayed, and has been in rotary motion with it for some time, while the borax -glass is free from lead globules ; after which the flame is allowed to act only on the borax, and the zinc not yet volatilized in the fusion with the lead is thus completely removed. When the lead shows a clean surface it is heated rather strongly for a few moments, and poured out on the anvil if the fusion was performed on an ordinary piece of coal, or allowed to cool slowly with the borax-glass if in a coal crucible. The cupriferous lead is cupelled just like that obtained from the foregoing metallic compounds rich in copper. c. Assay of vietalUc compounds in loMch lead or bismuth is a chief ingredient. Here belong the argentiferous lead and bismuth, obtained on a large scale ; the mineral chilenite from Chili may also be mentioned here. A small piece of the argentiferous lead is beaten out, cut up with the scissors, and from two to five, or even ten centners weighed out, according to the amoujit of silver expected. For the sake of dispaich a certain quantity is weighed out accurately, and then the amount of silver is calculated for one ctr. It is only advisable to begin at once with the cupellation in case of quite pure lead ; generally it ia TELLURIUM AND ANTIMONY A CHIEF INGREDIENT. 371 better to fuse the weighed portion in an excayated coal or a coal crucible, and to treat it for a short time with the 0. P. With lead containing much copper regard must be had to the remarks on p. 363, about the complete separation of the copper in the fine- cupellation. As bismuth is brittle, a quantity sufficient for several assays is broken off with the hammer on the anvil and made as fine as pos- sible. Then a weighed portion, of about five ctrs., is fused in an excavated coal with borax-glass for some time in the 0. P., and the fluid metallic button poured out upon the anvil, which will not cause the slightest loss if carefully done. The button is then subjected to the scorification, like argentiferous lead. In separating the oxide of bismuth thus formed from the argentiferous bismuth button, which is to be subjected to the flne-cupellation, great care must be taken to lose no fragments, since the bismuth is brittle. The button should never be lifted out of the oxide, but the latter must be gradually removed from it with the pliers, Fig. 39. Argentiferous bismutx never yields a silver button with a bright surface, and it is therefore necessary to fuse the button obtained from the scorification with a piece of test lead weighing forty to sixty milligr., and then proceed with the fine-cupellation. d. Assay of substances in which tellurium, antimony, or zinc forms a chief ingredient. Here belong hessUe and dyscrasite, which occur in nature, and also argentiferous antimony and zinc. One centner of the substance is fused on coal or in a coal crucible with five ctrs. of test lead, under borax-glass, with the K. P., and an opportunity is given to the metals in combination with the silver to volatilize by afterward treating the metallic button, rich in lead, with the 0. P. alone. Zinc volatilizes rather easily ; so does anti- mony, although it is somewhat difficult to remove the last ,portions ; but tellurium can only be partially volatilized, and must therefore be separated through oxidation by cupelling it with a large amount of lead. When the antimony and zinc seem to be volatilized the blast is stopped, the silver-lead separated from the slag, after the assay cools, and the cupellation is begun. When the lead is free from the volatile metals in question, it can be at once cupelled in two periods, but otherwise, as in case of native telluride of silver and other metallic compounds of silver containing tellurium, the scorification 372 plattnek's blowpipe analysis. must be repeated, with fresh quantities of lead (five ctrs. each time), 60 long as the resulting silver button, containing lead, cools with a dark colored surface, before proceeding to the fine-cupellation. Finally, if after the fine-cupellation the silver button solidifies with a reticu- lated, dull, grayish-white surface, this indicates that traces of tel- lurium are still present. Another centner of test lead must be added and the fine-cupellation repeated. One centner of pure telluride of silver requires nearly twenty centners of test lead, and with about 62.7 V. of silver suffers a cupellation loss of nearly 1.5 milligr. silver, 80 that only about 6l7« of silver can be actually obtained. e. Assay of mdallic compounds in which tin forms a chief, or only a secondary ingredient. In this class belong argentiferous tin, bell and gun metal, and several other alloys containing tin, which are employed in the arts. The substance is cut up, or finely divided in some way, and on. centner weighed out and mixed in the mixing capsule with 5 to 15 ctrs. test lead, according to the amount of copper present, 50 milligr. soda, and 50 " borax-glass. The mixture, wrapped in soda-paper, is treated on coal or in a coal crucible, with a strong K. P., until the tin or metallic compound is fused to a globule with the lead, and the soda, which prevents the easy oxidation of the tin, is melted to a glass with the borax. The metal alone is then touched with the blowpipe flame, for which pur- pose the blue flame is best suited, but only so that the very easily oxidizable tin may oxidize slowly, while the oxide is taken up by the fluid glass. When globules of reduced tin appear on the border of the slag the blast is stopped and the assay allowed to cool, after which the lead, still containing tin, is treated on another coal with a spoonful of borax-glass in E. F. until all is well fused, and then in the 0. F., in the same way as before with soda and borax, until the lead shows a bright surface, no longer covered with oxide of tin. It is then cupelled like any other argentiferous lead obtained from a fusion. IKON OB STEEL THE CHIEF INGREDIENT. 373 f. Assay of metallic 'compounds in which mercury is the prevailing ingredient. This includes native and artificial silver amalgam and argentif- erous mercury. In weighing these substances the scale pans, if of silver or gilt, must for well known reasons be covered with paper and the balance then adjusted, after which one ctr. of the compound is weighed out and put into a small glass tube, sealed at one end and blown into a bulb, as shown in Pig. 74, p. 261. The tube is held somewhat inclined and very gradually heated over a spirit-lamp, and the distillation continued until the metal remaining behind has been for some time at a red heat. By turning the tube and tapping on it, when it is somewhat cooled, all the separated mercury is collected into one drop and shaken out. When the metallic compound subjected to distillation was a silver amalgam, the silver remains in the bulb aa a single porous globule, which can be easily shaken out if the heat was not too high. This globule is fused with one, or if it appears to contain copper, with two or three ctrs. of test lead, under a cover of borax-glass in the E. F. on coal, and the resulting metallic com pound, rich in lead, is cupelled in the usual way. If the compound distilled was only an argentiferous mercury, a very trifling residue remains, which adheres firmly to the glass and cannot be shaken out. The bulb of the tube must then be cut off, filled with a mixture of one ctr. of test lead and half a spoonful of soda, placed in an excavated coal, or a coal crucible, and the lead melted together with the residue of silver in a strong K. F. The resulting metallic compound fiows out from the melting glass, and, after cooling, can easily be detached from the coal and glass and cupelled. Several centners of mercury may be distilled if the amount of silver is suspected to be very small. g. Assay of metallic compounds in which iron or steel forms the chief ingredient. Here belong, besides iron and steel, the iron hears mentioned on p. 182, which form under certain circumstances in smelting argen- tiferous ores and products. Neither iron nor steel can be directly united with lead before the blowpipe, so they must first be combined with sulphur, and then they will yield up their silver to the lead just as readily as an argen- tiferous iron pyrites. Hardened steel must first be softened by heat, ing, and then, after cleansing its surface from the resulting magnetic 374 plattxbk's blowpipe analysis. oxide by filing, the quantity necessary for an assay is reduced to a fine state by beating or filing. Iron bears being more or less brittle, can often be easily reduced under the hammer. From the divided metal, which may remain in pieces weighing from twenty to .thirty milligr., one ctr. is weighed out, and mixed with ^ ctr. powdered sulphur, 8 " test lead, and 1 spoonful borax-glass. The mixture is poured into a soda-paper cylinder and treated on coal, or in a coal crucible, with the E. F., until everything is fused to a fluid ball. The sulphur first combines with the easily fusible lead, and the iron, after continued blowing, begins to glow, taking a part of the sulphur from the lead to saturate itself, and combining then as proto-sulphide of iron with the lead, which still contains sulphur, to a quite fluid mass which is surrounded by the melted borax. A single spoonful of borax-glass being insuflScient to take up all the iron which must be oxidized by treating the assay with the 0. F. after this fusion, another heaped spoonful of the flux is then melted together with the already fused globule, and the whole treated with a powerfully oxidizing flame, until the impure lead begins to separate from the glass. The coal is now held so that, for the most part, only the lead is touched by the outer flame, in order that the sulphur may pass ofi' and the iron be oxidized and dissolved in the borax. After all the sulphur is gone and the iron separated the blast is stopped, and the silver lead, which has a bright surface, is allowed to cool. If it is of a gniyish-white color, it is cupelled, and the weight of the silver button ascertained ; but if it is black and brittle, it must be exposed to a second oxidation before it can be cupelled. 2, THE GOLD ASSAY. Like silver, gold can be separated from its combinations in the dry way, and it is therefore possible to ascertain with the blowpipe the amount of gold present in ores, minerals, and metallurgical and artificial products. In this method gold suflers no cupellation loss, since it cannot be oxidized. Gold, however, seldom occurs in nature without containing somu silver {vide p. 375), while silver ores are very frequently more or less auriferous, and since the silver cannot be separated from the gold in tlie dry way, the separation of gold in a pure state is somewhat more eomplicated than that of silver. ASSAY OF GOLD AND AUKIPEROUS SILVER OEES. 375 With reference to the quantitatiye assay for gold the various minerals, ores, and products may be divided into : A. Gold ores, auriferous silver ores, and argentiferous and aurip erous metallurgical products. B. Metallic compounds, viz., a. Such as consist only of gold and silver; b. Such as contain, besides gold and silver, other metals, ai copper, platinum, iridium, palladium, and rhoaium ; c. Such as consist of gold and mercury. A. Assay of Gold Ores, Auriferous Silver Ores, and Auriferous and Argentiferous Metallurgical Products. This includes: 1. Native tellurium, which usually contains some gold, but has not any silver. 2. All the minerals mentioned ou pp. 375-376, which contain silver as well as gold. 3. The auriferous iron and copper pyrites occurring in various places. 4. Rohstein and lead matt obtained from auriferous silver ores. 5. The grind- ings and gold scraps of gold and silver smiths. In the case of gold ores proper, containing little or no silver, the quantity of assay powder necessary for several assays is prepared, according to p. 349, and an assay made from it just as in the silver assay. After the cupellation, the color of the button will show whether the gold is pure or contains silver, since even two per cent, of silver is sufQcient to give the gold a brass-yellow color. If the button has a pure gold color, its weight may be immediately deter- mined on the balance, or on the scale, according to p. 38, et seq. ; but a lighter color indicates silver, and then a further separation must be effected, as will be described hereafter. From the other substances, containing more silver than gold, a quantity of assay powder suflBcient for ten or fifteen assays is pre- pared, and a preliminary assay of this is first made for silver. From the amount obtained a calculation is made of the number of assays necessary to obtain a quantity of silver so great that the gold in it may be quantitatively determined. If it is a substance contain- ing only about 0.11 pound of silver in a hundredweiglit, or 0.11 Vo, and in which but little gold is suspected, more assay powder must be prepared and at least twenty-four assays weighed out; but if it contains more silver, perhaps as high as 0.28 Vo, ten or fifteen assays will be enough. It is in general advisable to make as many assays as possible, with a substance poor in silver, because the proportion of gold to silver can be determined quantitatirely 376 plattneb's blowpipe analysis. only in a portion of the alloy which is large enough to be weighed on the balance. If the substance contains several per cent, of silver, only a threefold or fivefold assay is made. The separate assays are charged precisely as in a silver assay, with borax and test lead ; if the substance contains copper, the quantity of lead must be increased in proportion to the probable amount of that metal present. Each assay is fused exactly according to the directions given for the silver assay ; the fine-cupellation of the raw lead from each assay, however, is not performed separately, but in the manner now to be described. When all the assays have been fused, and the lead freed from slag and hammered into cubes, these are placed two or three at a time, if their united weight does not exceed fifteen ctrs., on a well-heated cupel, and the scorification begun as described in the silver assay, p. 357. After the scorification has been carried as far as is there stated, it is stopped, and the litharge and lead button lifted off from the bone- ash, which is not yet permeated with oxide, and set aside, while a new cupel is made, heated well, and another scorification performed with two or three more pieces of raw lead. This operation is per- formed on all the lead, and the resulting buttons, which contain the concentrated silver and gold, are all placed on a fresh, well-heated cupel, and the concentration of the gold and silver continued until the rich lead is only the size of a large mustard-seed. This button is then subjected to a fine-cupellation on another cupeL When the substance containg a great deal of copper, so that the silver is not pure after the brightening, a little test lead is added and the button cupelled fine on a free spot of the cupel. The auriferous silver but- ton obtained is accurately weighed and then parted in the manner described below, under metallic compounds. For the parting the auriferous silver button must always be large enough to weigh, since its true weight cannot be read upon the scale on account of the greater specific gravity of the gold. When pure pyrites, or very pyritiferous ores with little silver, or metallurgical products consisting chiefly of metallic sulphides, are to be assayed for gold, another method must be employed to conien- trate the silver and gold contained in them. Should the finely- powdered ore or product contain not less than about 0.11 */« of silver, twenty-four to thirty-six ctrs., according to the richness, are weighed out in portions of three ctrs. each, and the separate portions put into a clay capsule, p. 23, which has been painted with reddle, and roasted without the addition of any carboniferous substance, as in the quantitative copper assay. When no more fumes of sulphurou* ASSAY OF GOLD AND AURIFEROUS SILVER ORES. 377 acid can be smelled, the roasted stuff is rubbed in a mortar and again ignited in the capsule, until no signs of any escaping sul- phurous acid can be noticed. This is done with all the weighed por- tions. The roasting can be performed in a rery short time if one is provided with a gas-lamp, or a spirit-lamp with double draught, — as it is then only necessary to heat the whole weighed quantity of ore at once to a low, red heat, in a thin, flat porcelain dish, oyer the lamp, with access of air, stirring it from time to time with the iron spatula, p. 40, and keeping it in a glowing state, until the smell of sulphurous acid is no longer perceptible. After the whole twenty-four or thirty-six ctrs. are roasted, the ore, or product, is put in a porcelain vessel, p. 43, corresponding to the quantity of the substance and enough hydrochloric acid added to dissolve the oxides mentioned below. The porcelain vessel, covered with a watch-glass, is set upon a wire frame stretched over a brass ring, above the feeble lamp-flame, and the solution is begun with the aid of heat. Sesquioxide of iron, oxide and sulphate of copper, and the simultaneously forming chloride of silver, are dissolved. The gold remains in the metallic state if the roasted ore is free from metallic oxides which dissolve in hydrochloric acid with evolution of chlorine, but if it contains such oxides, for instance, proto-ses- quioxide of manganese, the gold also goes into solution. Any earthy admixtures not soluble in hydrochloric acid, likewise remain behind. After complete solution of the soluble portions, the whole is evaporated to dryness, preferably on the water-bath, and the remaining mass is warmed with enough water to separate the solu- ble chlorides from the now insoluble chloride of silver and the other insoluble portions. The whole is then treated with a solution of ferrous sulphate, to precipitate the gold in solution, stirred, and allowed to settle. When the liquid is clear it is flltered, the precipi- tate and residue washed with water, and dried on the filter in a porcelain dish over the lamp-flame, without unfolding it. The dry filter is then unfolded, five ctrs. test lead apd a spoonful of borax- glass carefully mixed with the powder upon it, and the filter folded again. After which, the upper part is cut off, if none of the charge has touched it, while the lower part with the charge is wrapped tightly together and placed in an excavated coal, or a coal crucible. The paper is first charred and mostly destroyed by a gentle 0. F.,. and the whole is then fused with a good R. F. The test lead decom- poses the chloride of silver, and the silver and gold unite with the lead, while any earthy matters present are dissolved by the borax, The raw lead is then cupelled in two operations, as in the silve* 378 plattxer's blowpipe analysis. assay, and the auriferous silver button further treated, as will be hereafter described in the parting of gold and silver. Another method, feasible for any assayer who has a muiile and wind-furnace at hand and is practiced in the use of the blowpipe, is the following. A very poor ore may be used, which would necessitate the treatment of three or four pounds in order to obtain a weighable button of gold by the ordinary muffle assay. The auriferous silver, from seventy -five to one hundred and twenty grm. of the ore or product in question ia first separated by any of the methods known to all assayers, viz., by a scorification assay in the muffle, followed by cupellation of the raw lead in the cupel, or by smelting the roasted substance with alkaline fluxes, litharge, or test lead, and other reagents, in clay crucibles, concentrating the lead by scorification under the muffle and then cupel- ling the enriched lead. The auriferous silver button thus obtained is weighed with the ordinary assay weights, the amount of silver contained in the test lead or litharge em- ployed is deducted, and from the result the amount of silver and gold together in the ore is calculated. Then, after separating the silver by the method to be directly given, the weight of the gold is determined on the measuring scale, and from it the proportion of gold and silver separately ascertained. If the system of gramme weights is used throughout there will be no difficulty whatever in making the necessary calculations. B. Metallic Compounds. a. Consisting only of gold and silver. Thfs includes native gold, gold alloyed with silver, and the argen- tiferous gold or auriferous silver from the assay of auriferous min- erals, ores, and products. There is no sure way of easily dissolving or slagging off one of these metals in the dry way, so as to separate the other pure and without loss, and it is necessary to perform the separation with nitric acid, both in the commercial and blowpipe assays. In the separating process, which is called parting, the proportion of silver to gold in the alloy must be not less than 2.5 : 1 ; otherwise the silver will be imperfectly; or not at all dissolved. The amount of gold must, therefore, be previously ascertained, and if it exceeds this limit the lack of silver must be supplied. Touch needles are used in the muffle assay, aud in blowpipe assays, where very small quantities are em- ployed, although not indispensable, these may be replaced by a small stock of alloys of known composition, which with a touchstone, p. 53, are of great advantage when frequent gold assays are made. Gold with only a few per cent, of silver is light brass-yellow, and if it has 60^ no yellow color is perceptible. From its more or less yellow color the approximate composition of the alloy can be esti- mated, as well as the amount of silver necessary to produce the METALLIC COMPOUNDS OF GOLD AND SILVER. 379 required proportions, but this may be more exactly ascertained from the streak on the touchstone. When native gold, of a brass- yellow color, is to be assayed for fine gold, it may be assumed that the amount of silver is unimportant, and fifty to eighty milligr. being weighed out, are fused with two and a half times the quantity of silver free from gold, which has been reduced from chloride of silver with a little borax -glass on coal in the E. F. A very light brass-yellow indicates a more considerable proportion of silver, and in this case only twice the weight of silver is added. When the alloy is silver-white, consisting perhaps of 60 '/, silver and 40 •/« gold, the proportion of silver cannot be estimated, and it is tlien necessary to fuse the weighed portion with fully half as much pure silver. Care must be taken in fusing the alloy with the silver and borax that the gold is equally distributed throughout the silver, and on this account the button must be kept for some time in a fluid state, while the E. F. is allowed to act only on the borax bead. The alloy obtained from mineTals or gold ores proper is generally richer in gold than in silver, and hence in this case also the button should be fused with two and a half times its weight of pure silver. As regards the alloy obtained from auriferous silver ores, pyrites, or matt-like pro- ducts, the gold is generally much less than one-third or one-fourth, and no silver need be added to such a compound. When the silver in native gold, or in an artificial alloy of gold and silver, is also to be determined, the weighed metallic compound, before being fused with the pure silver, must be cupelled with one or two ctrs. of test lead, to remove any admixture of easily oxidiza- ble metals, as iron, copper, etc., and the resulting button weighed, after which the silver is determined by difference when the weight of the separated gold has been ascertained. When regard must be had to the cupellation loss suffered by the silver, all of the litharge and the bone-ash which is permeated by it must be reduced on coal, with the addition of soda and borax-glass, the resulting lead cupelled and the weight of the silver button as ascertained on the scale added to the amount of silver previously found by difference. The surface of the alloy to be parted is increased by hammering it out between paper, and it is then heated to redness on coal with a weak blowpipe flame, so as to lessen the increased density, after which it is bent into a small roll. Very small buttons do not lequire this preparation. It is now laid in a small porcelain vessel, Fig. 63, and chemically pure nitric acid of 1.3 sp. gr. then poured over it in 380 plattxee's blowpipe AJS'ALYSIS. slight excess. The vessel is then placed oyer the free lamp flame on the wire frame D, Pig. 7, and covered with a watch-glass. The silver dissolves readily, leaving the gold in a black metallic mass, which preserves the shape of the compound when considerable gold is present, but otherwise is divided into several portions. As soon as the yellow fumes cease the flame is brought nearer, and the acid heated to gentle boiling for a few minutes, and then the wire frame is turned to one side and the vessel allowed to cool until it can be held with the fingers. Then the silver solution is carefully decanted from the gold on the bottom with the aid of a glass rod, and, for the flake of certainly removing all the silver from an alloy rich in gold, the remaining gold is boiled with fresh acid. When all of the silver solation is decanted the vessel is half filled with distilled water and again boiled, after which this water is decanted and the washing repeated several times, especially if the amount of gold is consid- erable.* When the last wash- water has been poured off the gold is dried thoroughly in the vessel over the flame, care being taken not to heat it too strongly, or it will adhere very firmly to the porcelain. The dried gold is generally in a finely-divided state when its amount is trifling, and it is then advisable to mix it in the vessel with a little borax-glass and about one ctr. of test lead ; pour this mixture into the mixing capsule, and then transfer it to a soda-paper cylinder, and fuse the whole in a moderate R. F. on coali After thorough fusion the auriferous lead is separated from the glass by very carefully ham- mering it between paper, and is cupelled fine at once on a well- heated cupel of sifted bone-ash, covered with elutriated bone-ash. Gold forms a brittle alloy with lead, if in considerable proportion, and hence loss may ensue if the rich lead is strongly hammered or pressed. The gold button is weighed or measured, according to its size {vide p. 28). Should the amount of gold be considerable it may be shaken into a platinum spoon or a clay crucible and heated to redness. The epoon is heated over the spirit-lamp, the clay crucible in a square coal, as described in the quantitative lead assay, the crucible and coal being uncovered and only a low red heat applied. The heated * The silver solntion is decomposed by adding hydrochloric acid, and the resulting chloride is washed, dried, and preserved until a quantity is on hand, when it is reduced by placing it in a porcelain vessel, pouring water containing some hydrochloric acid over it, and then adding a piece of zinc. The well-washed reduced silver is melted to a button in the R. F. on coal, with a little borax. ASSAY OF METALLIC COMPOUNDS. 381 gold, which has baked together and has a dull gold color, is then weighed. i. Assay of metallic compi'-iinds which contain other metals besides gold and silver, as copper, platinum, iridium, palladium, or rhodium. 1. Gold alloyed with both copper and silver. Thirty to fifty milligr. of the alloy are weighed and fused with 3.5 to 8 ctrs. test lead, according to the copper present, with a good E. F. under borax-glass on coal, and the resulting lead cupelled like any other lead containing copper, p. 363. Should the argentiferous gold button resulting from the fine-cupellation seem too impure, owing to a small admixture of copper, it must be cupelled fine at once on a free spot of the cupel after adding one ctr. of test lead. When both the gold and silver are to be determined the refined but- ton is weighed and the two metals are then parted as above described. There is undoubtedly some cupellation loss in cupelling such an alloy, but this can be ascertained by reducing the litharge and treat- ing it as described on p. 379. 2. Here are included alloys of gold with platinum, with platinum ftnd silver, and with platinum, silver, and copper. a. Gold and platinum. When the amount of platinum is consid- erable, the separation is best efiected by dissolving thirty to fifty milligr. of the alloy in aqua regia (three parts of hydrochloric and one of nitric acid), by warming it in a beaker-glass, adding chloride of ammonium to the solution, and evaporating the whole to dryness in a porcelain dish at a moderate temperature, so as not to decom- pose the salt. The residue is then washed on a small filter with alcoliol of 75" to 80°, until a fresh portion of alcohol is no longer colored yellow. By this means the gold is dissolved out and may be precipitated in the metallic state, after adding water to the solution and removing the alcohol through evaporation, by warming it with a solution of ferrous sulphate, allowing it to settle and collecting it on a filter. The filter is unfolded, dried in a porcelain dish over the lamp, folded up again, and incinerated over the agate mortar, being held up by one edge with the forceps. The ashes are mixed Tvith about fifty milligr. borax-glass, wrapped in soda-paper, and the divided gold fused to a button with the 0. P. on coal, while 383 plattner's blowpipe analysis. the ashes are slagged off. This button is freed from the borax be- tween paper on the anvil and weighed. As alloys containing much platinum rarely require to be treated, this separation, 'which requires much time, is seldom made. It is more frequently the ease that gold containing but a small quantity of platinum is to be assayed for fine gold. Thirty to fifty milligr. of such an alloy are fused thoroughly with three times as much pure silver, the alloy then hammered as thin as possible, heated to redness, rolled up and treated a few times with nitric acid according to p. 378. By boiling the alloy somewhat longer than if it were free from pla- tinum, the latter is dissolved with the silver, leaving either pure gold, or, if there was several per cent, of platinum in the original alloy, gold with a little platinum. In the first case the gold is boiled with distilled water, washed a few times with cold water, dried, heated to redness in a platinum spoon, and weighed. In the second case, however, the gold does not show a pure gold color after being weighed and fused with a little borax on coal, and it must be again fused with three times its weight of silver, after which the platinum can be completely removed by nitric acid. p. Gold, platinum, ani silver. When no regard is had to the silver the method just described is exactly followed, but if the silver is to be determined it must first be extracted with sulphuric acid. To do this with proper accuracy the alloy should contain, according to Chaudet, for one part of gold and platinum not less than one and a quarter nor more than two parts of silver, because some platinum seems to dissolve with more silver. When silver is lacking, an accurately weighed quantity of pure silver must be added, and if gold is lacking the alloy must be melted with pure gold, to secure the necessary proportions of the metals. Thirty to fifty milligr. of. the alloy being weighed out and brought to the proper proportions by fusing it with gold or silver and borax-glass on coal, the button is beaten as thin as possible, heated to redness, and rolled up. After being weighed to see that no mechanical loss has occurred, it is covered with concentrated sulphuric acid in a porcelain vessel and boiled for ten minutes. After cooling somewhat, the acid solution, con- taining sulphate of silver, is decanted and the porous metallic residue boiled five minutes longer with fresh acid to complete the separation of the silver. The remaining roll is boiled with distilled water, dried, ignited, and weighed; the difference gives the weight of the silver. The gold and platinum are then separated by fusion with silver and solution in nitric acid, as described under a. ASSAY OF METALLIC COMPOUNDS. 383 y. Gold, platinum, silver, and copper. The copper is first separated by cupelling the alloy with test lead as described on p. 381. If the gold cannot be made fine, owing to the presence of too much plati num, the rest of the lead is separated by means of boracic acid, as given in the qualitative assay, p. 273; it being assumed that the cop- per has been separated on the cupel. The silver is then removed with sulphuric acid, and the gold and platinum separated as above. 3. Gold containing iridium. The iridium can be very easily detected and separated by treating the alloy with aqua regia, which dissolves the gold and leaves the iridium as a black powder. When the decomposition is effected the gold solution Is diluted with water, filtered, and the iridium well washed. The gold is precipitated by warming it with ferrous sulphate according to p. 381, and deter- mining it as there directed. Any copper in the alloy is first re- moved by cupelling it with three to five parts of test lead, and sub- sequently every trace of lead is removed with boracic acid on coal, if the gold containing iridium cannot be made fine by simple cupellation. 4 Gold containing palladium. Thirty to fifty milligr. of the gold containing palladium are fused with three times as much silver and treated with nitric acid, as described in the separation of gold from platinum. The gold remaining behind is boiled and washed with distilled water, ignited, and weighed. Should the alloy not be fre« from easily osidizable metals, the separation of the gold from the palladium is preceded by cupellation with three to five parts of test lead, and, if necessary, treated with boracic acid on coal. The silver is precipitated from the diluted solution by salt and the palladium in the metallic state by zinc. 5. Gold containing rhodium. According to del Eio, when the gold is the prevailing constituent the alloy is dissolved without residue iu a(iua regia, and the gold can then be precipitated, free from rhodium, by ferrous sulphate. According to Berzelius, rhodium can be separa- ted from platinum, iridium, and osmium, by fusing the finely-divided alloy with bisulphate of potassa, which dissolves it and leaves the other metals. Gold being likewise insoluble, this method can bo applied to gold containing rhodium if the alloy is converted into a thoroughly porous state. Thirty to fifty milligr. of the alloy are weighed out, fused wii^h borax -glass and three times the weight of pure silver, then beaten out as thin as possible, annealed and bent into a roll. This is treated with nitric acid until all the silver is dissolved, leaving the spongy gold and rhodium in the shape of the 384 plattxer's blowpipe analysis. roll. The silver solution is decanted, the roll boiled and waslied well with water, then dried in the porcelain vessel. It is now gradually heated in the large platinum spoon or a platinum dish with a suffi- cient amount of bisulphate of potassa, until the salt is fluid at a low red heat. The rhodium and any remaining silver dissolve with lively evolution of sulphurous acid, imparting a dark red, almost black, color to the salt. When the evolution of sulphurous acid ceases and the fluid salt becomes quiet, it is poured off from the gold upon the iron anvil as completely as possible, using the iron spatula for the pur- pose, and the fusion is repeated with fresh bisulphate. This portion, which is only slightly colored, having been poured off, the gold is boiled a few times with distilled water in a porcelain vessel, dried, ignited, and weighed. It is safe to ascertain, in case much rhodium was present, whether this gold is quite free from rhodium, by again fusing it with three times its weight of silver, dissolving it in the shape of a roll in nitric acid, treating it again with bisulphate of potassa, washing, drying, igniting, and reweighing it. A trace of remaining rhodium will be shown by the pale yellowish color imparted to the bisulphate, and if weighable is also detected by the difference in the weight of the gold. c. Assay of metallic compounds of gold and mercury. About fifty milligr. of amalgam are weighed out, the scale pans being covered with paper if of silver or gilded, and then distilled just like the silver amalgam, p. 373. The remaining gold is cupelled with one ctr. test lead and weighed. If a light color of the button indicates silver, this is to be separated by the process described on p. 380, and the amount of gold and silver reckoned, after again weighing the gold button obtained from the separation. When one ctr. of the mercury to be treated contains a weighable quantity of both gold and silver, the method given on p. 373 is fol- lowed exactly, and the argentiferous button melted with two to three parts of pure silver and separated as above. The difference in weigh'; between the argentiferous gold button and the gold button gives the weight of silver. When the mercury is very poor and one ctr. will not afford a weighable argentiferous gold button, several centners are distilled in a small glass retort with a receiver over the spirit-lamp, or the distillation may be made in a tube blown out at one end, which is charged with one ctr. of amalgam, the condensed mercury THE ASSAY FOB COPPER. 385 cleaned out, and another centner of amalgam charged and distilled, continuing this until a weighable crust of gold and silver is observed in the bulb. The operation is then continued as directed for mer- cury containing silver, p. 373. The silver and gold are separated and determined as before. 3. THE ASSAY FOR COPPER. Copper can be separated with little difBeulty by means of the blowpipe, in the metallic state, when in combination, even if com- bined with other metals. Eegard must, however, be had to the different ways in which- it occurs, both in nature and in artificial products, as enumerated on pp. 246-249, because its quantitafive ■determination varies in the different cases. Substances containing copper are therefore most suitably classified as follows : A. Ores, minerals, and metallurgical products : — a. Containing volatile constituents ; h. Containing copper in an oxidized state, free from, or com- bined with, acids and water ; or slagged with earthy mat- ters, or combined in any other way. B. Alloys in which copper is the prevailing, or an accessory, in- gredient : a. Plumbiferous copper and cupriferous lead ; i. Compounds of copper with iron, nickel, cobalt, zinc, and bismuth ; either singly, or several at the same time, while lead, antimony, and arsenic frequently accompany it ; c. Copper containing antimony ; d. Copper containing tin. Before the fusion of substances belonging to class A, a, prelim" inary roasting is necessary to remove the sulphur and arsenic. A. Assay of Ores, Minerals, and Products, which, a, contain volatile constituents, as sulphur, selenium, and arsenic. This includes copper ores dressed on the large scale ; among min- erals, the compounds of copper with selenium, arsenic, and sulphur, pp. 246-247; among metallurgical products, copper matt, regulus, /cupriferous Rohstein, lead matt, tutty, or cadmia, etc. 386 plaxtkek's blowpipe analysis. EOASTING THE ASSAY. One ctr. of the assay powder is mixed in an agate mortar with three times its volume of pure dry charcoal dust, or with twenty to thirty milligr. of graphite, which is preferable in nearly all cases^ and especially for substances very rich in arsenic. Minerals which, on account of a considerable proportion of sulphide of antimony or bismuth, fuse easily together at a low red heat, viz., chalcostiMte, hournonite, emplectite, receive an addition of fifty milligr. pure ses- quioxide of iron, or pulverized hematite, which prevents them from fusing together, and has not the least injurious effect on the subse- quent separation of the copper. The carefully-mixed charge is transferred to a clay capsule, which has been painted with reddle, and is then spread out with the iron spatula. A square coal, p. 18, Fig. 19, F, with a hollow in it, either of natural or artificial charcoal, is then fixed in the coal-holder, p. 39, and so much of the coal cut out on one side of the cavity with the knife as is indicated by the slit b, Fig. 53, p. 40, so that the space cut out forms a channel leading to the cavity. The wire and pla- tinum shield, p. 40, are fixed in the cavity, and then the capsule is set upon the wire with the forceps, as shown in Fig. 82. In all these assays the aperture in the blowpipe tip should not be too narrow, p. 5. At first a moderate 0. F. is directed through the lower part of the channel a into ^_ 1 *'"p the empty space below the capsule, so as to ^H %miSi^ bring the sides of the cavity and the capsule ^H ^ ^ itself to a low red heat. The point of the ^'^■^^' blue flame must reach little or not at all within the coal-holder. When the substance begins to glow, if coal dust has been used, a moderate blast must be continued for some time, so that the particles of ore may not bake together, much less sinter or fuse, while the coal is consuming. When this has con- Bumed, which can be ascertained by examination with the iron spatula, first warming it in the spirit flame to prevent adhesion of the ore, the capsule is removed and the somewhat cooled charge poured into the agate mortar and rubbed fine. The ore will usually have changed in color and lies in a quite porous state in the capsule, 80 that it is seldom necessary to detach still adhering particles with the spatula. This roasting is completed in about ten minutes, and most of the KOASTING THE ASSAY. 387 volatile substances — sulphur, selenium, arsenic, and part of the antimony are removed, while the addition of coal has prevented to a great degree the formation of sulphates and arsenates. Some arsenic and sulphur- remain, however, partly as unaltered sulphides and arsenides and partly as acids combined with the metallic oxides formed, and to remove them as completely as possible a second roasting is required. The substance is therefore again mixed in the mortar with three times its volume of charcoal dust, the capsule painted anew with reddle and replaced with the charge upon the wire, when the roasting is continued. As soon as the intermingled coal is in full glow a somewhat stronger heat is employed, and the presence of still volatilizing constituents tested by smelling. When the charge ceases to give any odor, the rest of the coal is burned off and the assay regarded as thoroughly roasted. If, however, fumes are ses,n to escape, the assay must be again rubbed in the mortar, coal dust added, and a third roasting undertaken, during which the presence of volatile constituents is again tested by smelling. When no more fumes can be smelled and the coal dust is consumed, the capsule is removed and allowed to cool. Should fumes still be observed, which is only the case with substances containing much arsenide of nickel, even a fourth roasting is necessary; but generally the second is enough. Since it would be tedious to reweigh the assay, and thus ascertain whether its weight remained constant, the absence of any odor of volatile bodies from the glowing assay ia regarded as indicating the completion of the roasting when coal dust is added. The color of the roasted substance affords a tolerably sure sign of its richness in copper. The darker its blackish-brown color after cooling, so much the richer is it in copper, while a redder or lighter shade indicate less of this metal. In roasting with graphite the assay is kept at a red heat from the beginning of the roasting until no more volatile substances can be Bmelled. The graphite is less easily destroyed than the charcoal dust, and being, therefore, longer in direct contact with the substances, constantly exerts a deoxidizing influence on the volatile constituents, prevenbng the formation of sulphates or arsenates better than the coal,' which has to be added anew in order to decompose them. When, therefore, the fumes cease, the capsule is removed, and the substance, mixed with still undestroyed graphite, is carefully rubbed in tha mortar. This is necessary, because the graphite is more destroyed in the upper layer than below, and there may also possibly be imperfectly roasted portions here and there, which are thus brought into fresh 388 plattnek's blowpipe analysis. ooutact with tlie graphite. After spreading out the mixture again in the capsule, which, if necessary, is painted with fresh reddle, it is again heated to redness, but more strongly than at first. Sometime? at the commencement, fumes, resulting generally from some remain- ing arsenic, may be smelled, but shortly not the least trace can be smelled, and after continuing the blast awhile nearly all the gi-aphite is destroyed, and the assay can be remored from the coal. The only indication of a well-roasted assay is the absence of any odor of volatilizing constituents oyer the assay, which is glowing, and mixed with undestroyed graphite. When the assay contains sulphide of lead only a part of the sulphur combined with the lead is removed and basic sulphate of lead remains. Moreover, when examining an ore dressed on the large scale for copper, if it contains barytes or gypsum and must be first roasted, it is impossible to remove the sulphuric acid combined with the lime or baryta, either by means of coal or graphite. When the ore contains an admixture of calcite, this is likewise altered during roasting into sulphate of lime, if metallic sulphides are present. If disregarded, these undecomposable sulphates may have a very injurious effect on the success of the assay during the redaction of the oxide of copper formed, since they are decomposed by fusion -with alkaline fluxes, and give rise to the formation of sulphide of copper. During the fusion for black copper, therefore, regard must be hai to this point, and the remaining sulphur be made harmless as there indicated. The roasting is followed by THE EUSION FOE BLACK COPPER. The roasted substance, which may contain, besides oxide of copper, various metallic oxides and earthy matters, is charged for reduction with 100 to 150 milligr. soda,* according to the amount of silicic acid (quartz) present, 50 milligr. borax-glass, and 30 to 50 milligr. test lead. If the substance contains sufficient lead, or if there is considerable antimony, bismuth, or tin present, as m tetrahedrife, emplectite, and stannite, and the roasting has been conducted with great care, no test lead is needed, because the reduction yields an easily fusible alloy, from which the copper can be obtained pure. It is, to be sure, safer to add at least thirty milligr. test lead, even with plumbiferous sub- stances, on account of the unavoidable formation of sulphate of lead. The soda serves as a reducing agent for the oxide of cppper and other easily reducible oxides, and to slag ofi" the quartz or silicates ; * Tho soda and borax-glass must be pei-feotly dry, or else so lively a motion occurs in the mass during tho tusio-i that a mechanical loss can scarcely be avoided FUSIOK POK BLACK COPPER. 389 the borax as a solvent for oxides of difficult reduction, as oxide of iron, manganese, and cobalt, and for many earthy ingredients; the test lead takes up the reduced copper, and forms an easily fusible alloy, black copper, from which the pure copper can be separated in a short time. The roasted substance and charge are well mixed in the agate mortar, transferred to the mixing capsule, and thence to a soda-paper cylinder, as in the silver assay. In this charge, however, there is less test lead, and it does not pour into the cylinder so readily, so that the ivory spoon-handle, or the Bpatula, must be used to push the charge in small portions into the cylinder, after which all adhering particles are brushed in. The closed cylinder is then placed in a coal crucible, or in an excavated coal, and a pure E. P., at first very feeble, and subsequently made stronger, directed upon it until all the paper is destroyed, and either various sized metallic globules appear in the fluid glass bead, which is now to be regarded as a slag, or the reduced copper, united with the lead or other easily fusible metals, appears as a button beside it. From this time the reducing flame is directed only upon the slag, the position of which is so changed by slowly turning the coal that the separate globules can unite to one metallic button. After several times altering the position of the slag with regard to this fluid button, so that every part which has been in contact with the coal appears free from metallic globules on coming into the opposite position, the blast can be stopped and the fusion regai-ded as complete. The metallic button is either taken out with the forceps the moment it solidifies, or is allowed to cool in the slag on the coal, and then separated from it between paper on the anvil, after which the oxidizable metals combined with the copper are removed with appropriate fluxes or by simple volatilization, according to the processes described hereafter under the metallic compounds. The button must be light bluish-gray or whitisb, and have a weak metallic lustre.* Slag which is gray or black when cold, and is quite free from ntetallic globules, which can be best ascertained with tli'' magnifying glass, can be thrown away, but if it contains metallic globules, or has a more or less red color indicative of suboxide of copper, the assay must be treated some time longer in the E. F., and it is weU to add * All black copper free from antimony, bismuth, tin, and sulphur, is malleable; while that contaiuing vuxe. or less of these bodies, or trifling quantities of arsenic com- bined with niclcel and cobalt, is more or less brittle, and therefore the greatest care must be taken to avoid mechanical loss in removing the slag. 390 plattner's blowpipe analysis. about fifty milligr. of soda and a few grannies of test lead. Care must be taken to lose no slag when removing it from the black copper button, as it might be necessary to remelt it. As a rule, the assay is carefully examined with the glass after removing it from the coal, to see whether all the copper is reduced and melted to one button, so that the slag need not be previously separated from the black copper, in case a further fusion is required. If the surface of the black copper button is very gray or nearly black and without any metallic lustre, it is nearly certain to contain more or less sulphur, resulting from sulphate of baryta, lime, or lead in the roasted substance, or from imperfect roasting. The first named salts are decomposed by the soda during the reduction, forming at first only sulphide of sodium, which, however, afterward yields sulphur to the reduced metals and the copper. In case of imperfect roasting the substance still contains sulphates of the metallic oxides, which are very easily reduced to sulphides. In case the admixture of earthy or metallic sulphates in the roasted substance is considerable, and the reduction is made rapidly at a high temperature, the black copper button is covered with a very brittle crust of sulphide of copper and lead ; while if the reduction was made slowly, so as to afford the sulphur an opportunity to volatilize as sulphide of lead, the resulting button is sometimes tolerably free from sulphur. The metallic sulphides formed in reducing an assay containing a small quantity of earthy or metallic sulphates are also destroyed by continued fusion in presence of sufficient lead, so that in most cases the black copper button is free from metallic sulphides. In case the button is surrounded with a crust of sulphide of copper and lead it must be very carefully separated from the slag between paper, or, to avoid mechanical loss, the whole assay is melted on coal in the R. F., and the button taken out quickly as soon as it is solid. It is then melted on coal in the R. F., with about twice as much test lead and some borax-glass, and the borax bead beside the button treated with the R. F., until all the sulphur has volatilized with a part of the lead, leaving an alloy which shows a clean metallic surface on cooling. The button is then separated from the colorless glass and refined with boracic acid according to B, a. If the substance contained much antimony, and was therefore charged without test lead, then, in presence of sulphates, the sulphur is volatilized in combination with the antimony during the reduction, so that a copper button containing only antimony ii obtained, which is refined according to B, c. A copper button containing bismath or tin is freed fh>m a little Bolphnr by refiling u ia described below in B,b, a ORES CONTAIKINQ COPPER IIT THE STATE OE OXIDE. 391 i. Ores, minerals, and products containing copper in the state of oxide, or combined with chlorine; it ieing in the former case pure, or combined tvith acids or water, or slagged with earthy matters, or otherwise combined. Here are ranked atacamite, cuprite, tenorite, melaconite, crednerite, cupreous manganese ; likewise all the minerals mentioned on pp. 347- 248, containing sulphate, phosphate, carbonate, arsenate, chromate, vanadate and silicate of copper ; among metallurgical products, all sorts of slags from copper smeltings ; among artificial products, especially colors prepared fi'om copper and blue vitriol with other cupriferous vitriols. "With the exception of th'e vitriols and poor slags, a quantity of assay powder is prepared from the substance, and one ctr, weighed out and charged as follows, without roasting : 100 milligr. soda, 50 " borax-glass, 30-50 « test lead. In case phosphoric acid is present, as in phosphate of copper, which is not entirely reduced by the above charge, twenty mUligr. fine iron filings are added. The addition of test lead is unnecessary for cupriferous slags con- taining not too little oxide of lead, as in certain refining slags ; but if they at the same time contain protoxide of nickel, which is easily reduced and combined with the copper, it is better to add some lead. The substance is mixed with the charge in the agate mortar and fused just like the roasted substance, pp. 386-387. The soda acts partly as a reducing agent, and partly as a base for the non-reducible acids ; the borax, as a solvent for the earthy matters and metallic oxides of difficult reduction, and it also prevents the soda from sinking into the coal in their absence ; the test lead, as a protection against mechanical loss ; the iron filings, to separate the phosphoric acid as phosphide of iron, which, indeed, combines with the black copper, but is separated from it simultaneously with the lead during the refining, described under B, a. Blue vitriol, or other cupriferous vitriols, cannot be thus treated, since the sulphuric acid is reduced to sulphur, which, forming at first sulphide of sodium, is again separated after longer reduction, and com- bines with the reduced copper to sulphide of copper, and this cannot be freed from the sulphur without loss. It is safer to dissolve two hundred milligr. of the vitriol over the lamp flame in a porcelain ves- flel with water, converi, the protoxide of iron into sesquioxide with a 393 plattxer's blowpipe analysis. few drops of nitric acid at a boiling heat, precipitate the metallic oxides, from the hot solution with potassa, and then wash the precipi- tate well on a filter, which is dried and ignited over the mortar. The oxides and the filter ash are then mixed with one hundred milligr. soda, fifty milligr. borax-glass, and twenty to thirty milligr. lead, and treated as before for black copper. In case of slags so poor that the copper in a centner can scarcely be separated and weighed as a pure button, fifty to eighty milligr. of gold, beaten thin, is added, and the copper then combines so perfectly with it that none can be detected in the slag after fusion. The fluid gold must, however, be carefully brought into contact with every part of the likewise fluid slag during the reduction. If the slag con- tains only protoxide of iron, and suboxide of copper, the increase of weight in the button freed from slag gives the amount of the copper ; but if oxide of lead was present the button also contains lead, which must first be separated with boracic acid, as will be described iu the sf paration of lead from copper. If besides suboxide of copper protox- ide of nickel was present, this is likewise reduced, imparting to the gold a gray color and making it harder and more brittle, while it would cause too high an amount of copper if disregarded. The but- ton is therefore weighed and afterward treated on coal witn borax, so as to keep the blue flame in contact with the borax, when the nickel is oxidized and dissolved, coloring the glass brown, while the copper remains with the gold, and its weight is again ascertained. The sep- aration of the nickel is slow, but unattended by any loss of copper if carefully conducted. B. Assay of alloys in which copper forms an ingredient. a. Alloys of copper and lead. Here belong the plumbiferous copper obtained by the reduction of the foregoing substances with the test lead, as well as the cupriferoas lead obtained from the reduction of a roasted ore in the lead assaj^,. q. V. ; among metallurgical products are to be reckoned here, the cuprif- erous raw lead obtained on the large scale, and the liquation discs, carcasses and dross from the liquation processes. 1. The compound of copper with lead obtained from the reduction of one ctr. of any cupriferous substance, if rich in copper, is thus separated : — A shallow cavity, about four millim. deep and eight millim. wide at the top, is bored in the cross section of a coal or in a coal capsule. Fig. 15, in which vitrified boracic acid, fully one half the weight of the plumbiferous copper button, is fused; then the button is- ASSAY OF ALLOYS CONTAIlfllfG COPPER. 39d. laid beside it aiid fused as rapidly as possible, being covered with the blue flame. When this is done the blue cone is made to cover only the boracic acid, but not the button, which should also be constantly in contact with the glass on one side and the coal on the other. A slight fault in the inclination of the coal may very easily cause the- button to go under the glass, at once interrupting the oxidation, in which case the coal must be inclined toward another side and a strong slast used, so that the button may appear again. "While the glass is covered with the blue flame the lead is oxidized and at once dissolved in it. This process is continued until the button begins to assume a greenish color, and at this moment a more spreading flame is caused to act on the glass, so that the remaining lead is slowly oxidized, while the copper is pi-otected from oxidation, and the copper button does not .then sputter. If the cavity in the coal is too small, or the blast stronger than is just requisite, the copper almost always sputters, even when still combined with a little lead; the dimensions given above must therefore be observed, while the blast is just strong enough to keep the copper fluid and its surface bright. When the button shows perfectly the peculiar bluish-green color of melted copper, indicative of the proper fineness, the process is stopped, the solidified button removed from the still soft slag with the forceps, and its qualities ex- amined. If it has a copper-red color, can be hammered out without cracking, and when broken shows under the glass a true copper color and a hackly texture, which can, however, only be determined in case of larger buttons, it is certain that the copper is free from foreign "admixtures. If the slag on the coal is also transparent and. only colored yellowish with oxide of lead, there has been no chemical loss of copper, and the button may be weighed. Should the slag, however, show red streaks, or appear very red, this indicates a loss of copper, which can be very quickly determined, as follows : from horacic acid that is not saturated with oxide of lead, no lead can be reduced by a good E. P., while the dissolved oxide and suboxide of copper are very easily reduced to metal. It is only necessary, after removing the refined button, to treat this slag and the glass separated from the button for a time with the E. R, when it becomes transparent and yellowish on cooling, and the reduced copper appears in separate globules. These can be collected either by replacing the large button in the slag and fusing the whole with a powerful E. P. until all the email globules have united with the large one, which is then again removed from the slag ; or the slag may be at once broken up between paper, and removed from the metallic particles by triturating and washing it in a porcelain dish. The little copper globules . are thej 394 PLATTITBB'S blowpipe AKALTSI3. dried in the dish over the lamp, and weighed with the large button. If the glass contains also considerable oxide of lead, some lead is min- gled with the reduced copper, which in this case is generally all in one button, and is then fused for a short time with the E. P. in a cavity on coal with a little boracic acid, when the lead is soon sepa- rated and leaves the copper pure. This is then weighed with the large button. Should the assay substance contain more than an unimportant amount of silver, which has been ascertained beforehand by a silver assay, this must be deducted from the weight of the copper. In case the amount of silver in the copper button is to be determined, it must be fused with fifteen parts of test lead and cupelled accord- ing to p. 357, et seq. 2. In the lead assay, if the substance has been roasted before the fusion, cupriferous lead ores containing much copper yield plum- biferous copper, otherwise they yield cupriferous lead, if the lead prevails ; likewise in assaying poor copper ores, etc., for copper, the addition of test lead causes only cupriferous lead. The refining of plumbiferous copper has just been described, and to ascertain the weight of the lead, it is only necessary to weigh the alloy obtained from the lead assay, and then to deduct the weight of the refined copper and silver from it. The refining of cupriferous lead from a lead or copper assay, or lead obtained in the large way, as raw lead, cannot be made in one period, on account of the length of the ox- idizing process, but must be divided into : a. a concentration of the copper, ^. the refining proper. Both operations are performed with boracic acid as before, but if enough of this were employed at once to take up the oxide of lead formed, the remaining copper button would seldom be pure, since it would be concealed by the large quantity of slag before it was refined. a. A concetitrafion of the copper must therefore be first performed. The cupriferous lead from the lead assay is weighed and melted to a button in the E. P., with a little soda and borax-glass ; this opera- tion is unnecessary in case of the button from the copper assay. If lead, as raw lead, is to be examined for copper, one ctr. is weighed out and fused on coal, if not already in one piece. The cupriferous lead is tlien ti-eated with its weight of boracic acid on coal, just as in the refining process above described, so long as it can be kept from passing beneath the glass and until little globules of reduced KEFINING OF COPPEK. 395 lead are obsenred. "When the greater part of the lead has been thus removed, the process is stopped, and the button containing the concentrated copper freed from the glass on cooling. If the glass appears like a white enamel, as is almost always the case, there has been no loss of copper, and the /3. proper refining of the copper ensues, by which the concentrated plumbiferous copper button is refined according to p. 393. The lead is determined by deducting the amount of copper and silver, if any. i. Alloys consisting of copper with iron, nickel, cobalt, zinc, and bis- muth, either singly or with several of them at once, and containing frequently some lead, antimony, and arsenic. In this class belong : a. Bismuthiferous copper reduced in the assay of minerals con- taining bismuth and copper ; niccoliferous black copper obtained by assaying certain copper I'efining slags ; the frequently very impure black copper and the liquation residues obtained in the treatment on a large scale of cupriferous lead matt. (3. The black copper obtained in the large way from copper ores free from lead. y. German silver and other compounds of copper and nickel, sontaining very little or no lead. a. Refining of thecopper containing bismuth, lead, or nickel, ob- tained from an assay, as well as the frequently very impure black copper obtained in the treatment in the large way of cupriferous lead matt. The bismuthiferous copper obtained in the copper assay from min- erals containing these metals, where no test lead was added, must be (reated on coal alone in the 0. P., until most of the bismuth has volatilized ; then a little lead is added and the whole refined with boracic acid, when the trifiing residue of bismuth likewise separates. The black copper obtained in the large way is often very impure, and contains, besides copper and lead, iron, nickel, cobalt, zinc, anti- mony, arsenic, etc. ; it is very brittle, and can be hammered only into easily broken scales. Of this 60 to 80 mg. is fused on coal, with a little soda and borax-glass and 20 to 30 mg. of test lead, to a button, which is then treated with 50 mg. boracic acid, exactly according to p. 393, until either reduced globules of lead are observed in the glass, or the copper button is covered with a film of oxide and can only be kept fiuid with diflBculty. During this process, lead, iron, antimony, zinc, arsenic, and other easily oxidizable metals are oxidized, with "396 plattnee's blowpipe analysis. Bome nickel; the metals which volatilize with difficulty combine with the horacic acid, while the others partly volatilize and partly combine with the acid; a part of the nickel, however, owing to ita slight capacity for oxidation, remains obstinately with the copper and causes a thin film on its surface, hindering the'refining of the cop- per. By continuing the oxidizing process this film of protoxiSe of nickel is indeed taken up by the boracic acid and the rest of the nickel slagged off, but not without loss of copper. The remaining niccoliferous copper must therefore be fused with its weight of test lead and subjected to a new oxidation quite similar to the first. The surface is thus increased and the nickel oxidized with the lead almost without loss of copper. Should the slag, however, be red and some copper be reduced from it, after removing the refined button, this must be collected by triturating and washing the slag, and then dried and weighed. The nickel is not easily reduced unless the slag is saturated with oxide of lead and nickel, being usually only reduced afterward by using a very powerfully reducing flame. Such black copper being frequently rich in silver, the amount of this metal must be ascertained and deducted from the copper found. After learning to refine such a black copper it is easy to refine the 3)lumbiferous and niccoliferous black copper button obtained by as- saying a copper refining slag. Should the lead present not suffice to separate all the nickel a second addition is necessary. 13. Eejinivg of the Hack copper obtained in the large way from copper ores free from lead. This is generally combined with iron and occasionally with some zinc. Brass being a similar alloy, although containing much more zinc, will be included here. Any alloy of copper, zinc, and iron can be assayed for refined copper like plumbiferous copper. A quantity of the metal is made fine and one ctr. weighed and melted on coal to a button with one or one-half ctr. of test lead, as the copper contains much or little zinc and iron ; a little soda and borax-glass being added to the charge. This button is then treated with its weight of boracic acid just like any plumbiferous copper. The iron and part of the zinc oxidize with the lead, while part of the zinc is volatilized and the copper remains alone. Since the black copper in question sometimes con- tains a little nickel and cobalt, the remarks on the impure black copper above must be regarded here. Any copper in the slag may be obtained again as before described, and if there is an important amount of silver it must be determined according to p. 394, and deducted. ALLOTS OF COPPEK AND TIN. 397 y. ITie determination of copper m presence of much nickel, as in German silver, packfong, etc. The copper cannot here be determined accurately by refining with lead, since in slagging off so much nickel a considerable amount of copper is also slagged off. A method is giyen under the assay foi nickel and cobalt by which both the copper and nickel in such alloys may be determined pretty accurately with the help of the blowpipe and the wet way. c. Alloys of copper and antimony. Here is included especially the antimonial copper obtained m assaying tetrahedrite for copper. Antimony in combination with copper alone can be easily volatil- ized on coal in the 0. P. without loss of copper. The copper button is placed in a sliallow cavity on coal, or a coal capsule, and kept in a melted state with the 0. F., the point of which is occasionally di- rected a little to one side, so as to admit air freely to the assay. The antimony then volatilizes, leaving the copper behind. When there IS much antimony, and the coal is burned away so that the metal lies too deep, it is sometimes necessary to stop the process and complete the volatilization of the antimony in a fresh cavity. The purity of the copper is indicated by its bluish-green color while melted and its true copper color when cold, as well as by its malleability. Should these tests not be satisfactory, the oxidizing process must be repeated until it is quite pure, when it is weighed. The silver generally pres- ent, if it has not been already determined by a special assay, must be now determined, and if weighable, deducted from the weight of the argentiferous copper button. d. Alloys of copper and tin. Here are ranked the alloy of copper and tin obtained in assaying stannite for copper, and among artificial products ; bell, gun, and speculum metal, as well as ironze. Since boracic acid, when not combined with oxide of lead, melta with diflSculty, and has no particular solvent action on binoxide of tin, it is advantageously replaced by a flux which is easily fusible wid dissolves the binoxide. This flux is composed of— 100 parts by weight of soda, 50 « « « " borax-glass, and 30 " " " " silicic acid (quartz). 398 PLATTNER'S BLOWPIPE ANALYSIS. It is best to melt a quantity of this mixture in a platinum crucible and preserve the resulting glass in a well-closed bottle. To refine stanniferous copper sixty to eighty mg. of the above flux is melted to a bead on coal, and the alloy to be separated is laid beside it. For the compound obtained by reducing stannite the above amount is required, but for the other artificial products forty- five to fifty milligr. is enough. The bead and the metal are then fused with the R. F., so that the metal may assume a rotary motion, and the moment this occurs the flame is made somewhat more oxidizing and directed only upon the glass, but so as to cut off the access of air from it as much as possible. The button then begins to oxidize and the oxide of tin, which is mingled with protoxide of irou in the presence of iron, is immediately taken up by the glass. In case of copper from stannite, which through imperfect roasting is not quite free from sulphur, the sulphur is at the same time removed ; but if there is too much sulphur a loss of copper in the slag is unavoidable. It is then necessary to make a new assay. When, however, the metallic compound is such that the copper can be separated pure, the following points must be observed during the refining. During the oxidation of the tin the assay must be so held toward the flame that the alloy may always be in contact with the coal on one side and the glass on the other, so that no copper can be oxidized. The glass is capable of dissolving considerable oxide of tin, and the process is continued without interruption until it is completely saturated, which is indicated by the appearance of little specks of reduced tin here and there in the enamel-like glass. Upon this the process is stopped and the solidified metal removed from the still soft slag with the forceps, and transferred, with the trifling adherent slag, to another coal, where it is treated with sixty milligr, of the flux, just as before, until it begins to assume the color of melted copper. When this appears the glass is treated with a mod- erately strong and not too spreading E. P., until the metal beside it (to which, however, the air must always have free access) possesses the characteristics of pure melted copper. The blast is now imme- diately stopped, the button removed as before, and first examined as to color and then as to malleability. If it has a true copper color, and does not crack when beaten out to three or four times its original diameter, it can be regarded as pure, and weighed; other- wise it must be treated with twenty to thirty milligr. of the flux as above, so as to refine it perfectly. In this process of separation, which indeed requires some practice; care must be taken lest a part of the copper become oxidized and go THE LEAD ASSAY. 399' into the slag with the tin, which is, however, very easily purcei VL-d, because the suboxide of copper gives the glass a brownish -red color when cold. Such a slag is treated a few moments with the E. P., to. separate the copper, which is then united with the button by the side of the slag. The oxide of tin is not so easily reduced unless the glass is supersaturated with it. Some copper is always oxidized while removing the last portions of the tin, which by careful treat- ment amounts on the average to 0.3 milligr. for 25 milligr. of copper. 4. THE LEAD ASSAY. The quantitative determination of lead with the blowpipe can b& performed in two ways. The more complicated process is, however, only recommended for substances containing, besides the lead, copper, which is at the same time to be quantitatively determined; tlio other shorter process is applicable to all substances. The plumbiferous minerals, ores, and products can be classified into — A. Those containing the lead as sulphide. B. Those containing the lead as chloride and as oxide, free, or in the form of slag, or combined with acids. * G. Those containing the lead in the metallic state, combijied either with selenium, or with other metals. A. Assay of Minerals, Ores, and Metallurgical Products containing the Lead as sulphide. FIRST METHOD. The substances for which this method is especially suitable are :— all the minerals containing sulphide of lead mentioned on p. 217,, et seq., which are at the same time cupriferous, as lournoniter cuproplumhite, etc. ; and among metallurgical products, particularly cupriferous lead matt and plumbiferous copper matt. One centner of the assay powder is freed from volatile constituents- by careful roasting on a clay capsule painted with reddle, as iu the copper assay, p. 386, with addition of charcoal dust. Besidi*- the coal about fifty milligr. of sesquioxide of iron is added to sub- stances which sinter, or fuse together easily, as bournonite, etc. When all of the coal has been consumed at a low red heat (sul- phide of lead may easily be volatilized by a stronger heat), and iia- 400 PLATXXER'S BLOWPIPE ANALYSIS. more fumes of folatile constituents can be observed, the capsule is remoYed and the ore rubbed in the mortar and mixed with twice ita Tolume of fresh coal dust, after which it is replaced in the clay capsule and roasted the second time. When the fresh coal takes fire the presence of volatilizing constituents is quickly tested by smelling, and in case a considerable quantity of them is detected the coal is allowed to consume at a moderate red heat, after which it is again rubbed in the mortar, and if necessary roasted a third time with coal. Although seldom occurring, the third roasting is unavoidable when the substance to be assayed for lead contains metallic sulphides and arsenides which are decomposed with difiBculty. If after the second addition of coal the substance evolves no odor while the coal is glowing, or only a feeble odor of sulphurous acid, the assay may be regarded as well roasted, after the coal has been slowly burnt out from the ore. Lustrous particles of undecomposed sulphides must not be present, but the whole mass should have a dull, earthy appearance, and must lie in a porous state on the capsule. The roasted assay is charged, for the reduction of the oxide of lead in it, with — 100 milligr. soda (anhydrous), 30-40 " borax-glass. The soda, in common with the coal which surrounds the charge during the fusion, acts as a reducing agent on the oxide of lead, chiefly through the formation of carbonic oxide, and at the same time takes up the sulphuric acid remaining with the roasted oxides, especially the oxide of lead, forming sulphide of sodium. Any othtt reducible metallic oxides are separated in the metallic state, and the others are brought to the lowest stage of oxidation and then go into the slag. The borax prevents the soda from sinking into the coa. lining and dissolves the non-reducible oxides. The amount given is generally suflBcient to form a perfectly fluid slag ; but in case many earthy matters, or bodies to be converted into slag, are present, it is Bell to increase the amount of borax-glass to fifty milligr. *> Both of the fluxes are mixed with the roasted ore in the mortar, and then poured into the mixing capsule and transferred to a soda- paper cylinder, as in the preceding assays. The cylinder is not closed by pressing the comers of the empty part upward after rolling it together, as in the copper or silver assay, but downward, so as to lie upon the filled portion, in order that the wrapped up assay may rather have a hemispherical shape. ASSAY OF MINERALS CON'TAIXING LEAD AS SULPHIDE. 401 It is then placed in a clay crucible lined with coal, Pig. 31, p; 2.5. which must, however, be thoroughly dried as soon as it is made. The assay is then covered with so much fine charcoal dust that. when the clay-roasting capsule which serves as a cover is laid in an inverted position upon the crucible, the whole space between the capsule and crucible is filled. During this operation the crucible ia set on the cupel mould, Fig. 49, B, p. 39, or on a tripod of iron wire. A small piece of gas-pipe makes a good stand. Transl. The coal-holder is provided with an artificial or natural coal, but only an opening for the flame is bored in this with the borer. Fig. 48, p. .38, without cutting it out, as is necessary for the roasting, and the slit in the coal-holder is closed with the screen of sheet-iron, h, Fig. 53. The platinum wire, on which the crucible is to rest, ia set in without the shield, since the crucible protects the coal from being too rapidly burned through. The full crucible is now placed in the ring, Fig. 83, so as to leave a space between it and the coal all around, and especial care must be taken that the lower part of the crucible may be dis- tinctly seen through the opening at a, and not only the point of it. The clay capsule is placed upon the crucible and the whole cov- ered with a natural or artificial coal prism. Fig. 19, 0, p. 18 which fits into the coal? holder, being held by the projecting sides, ■ and has on its inner surface a cavity, o, and an opening,^, four mil- lim. wide. (The platinum wire may be replaced by iron. — Transl.) After arranging everything thus and providing the blowpipe with a tip having not too narrow an aperture, a strong 0. F. is directed through the hole a in a horizontal direction, so that the blue point of the flame is still seen outside. The temperature increases so rapidly from below that after a few minutes a little flame of burning carbonic oxide is seen at q. Fig. 83. If the coal is not too hard or dense, in which case only can the proper heat be produced, the most refractory assay will certainly be fused after blowing uninterruptedly 8 to 10 minutes. After that time has passed the blast is stopped, the coal cover removed, and the wire seized with the pliers at «, Fig. 55, p. 41, so as to raise the covered crucible and set it on the tripod, or other stand, to cool. In a successful assay there should be no coat of oxide of lead visible on the upper side of the coal cover near the opening, whiclk 402 PI.ATTNER'S blowpipe ANALySIS. ■would indicate so strong a heat that some lead was volatilized. Moreover, tlie fused assay must lie as a perfect ball at the bottom of the lined crucible, and be easily removed with the forceps from the almost uninjured coal lining. It happens very rarely that the lead forms one button, but it generally lies in the slag in several separate buttons, large and small. The slag is broken coarsely between paper on the anvil, and poured into a porcelain dish, when the larger but- tons, free from slag, are picked out and the slag washed from the remaining lead buttons by carefully triturating it with the agate pestle and pouring it off with the water, repeating the operation until all of the slag is removed. The remaining lead is then dried in the porcelain vessel. Should the previously removed larger but- tons not be free from slag, they must be beaten out on the anvil, cleaned with water, dried with the others, and weighed. When the roasting was carefully performed, the reduced lead can only contain copper, silver, bismuth, and antimony. The copper is found by fusing the lead buttons together on coal with borax-glass and treating them with boracic acid, according to p. 393. The silver is then determined by cupelling the resulting copper button with fifteen times its weight of test lead. Should bismuth be present in the substance assayed, as well as lead and copper, it is best to make two assays; one serving to determine the copper in the alio}', as well as the combined weight of the bismuth and lead, while the other is performed to determine the amount of the lead and the bismuth in the following way : The larger buttons produced are flattened out and fused, together with the smaller ones, in a porcelain vessel, Fig. 62, p. 43, or.e of the smaller ones there described, with about twenty times their weight of bisulphate of potassa, over the spirit-lamp, until the alloy is oxidized and combined with the sulphuric acid. More of the salt is added if necessary. Tlie fused mass is then further treated as will be described under the quantitative bismuth assay, and the sulphate of lead collected on a filter, dried thoroughly, weighed, and the lead calculated ; one hundred parts of the sulphate contain 68.3 parts of lead. By deducting this and the weight of the refined copper obtained from the other assay, the amount of bismuth IS obtained, at least approximately. When the assay contains antimony, only the greater part of it is removed by roasting, and a little remains and is reduced. The antimony in such an alloy can be qualitatively detected by treating it on coal in the 0. F., when it forms a white coat of oxide of antimony. The quantitative determination could only be made in ASSAY OF MINERALS CONTAINING LEAD AS SULPHIDE. 403 the wet way, and would not be very feasible on account of the small quantity pi-esent. Antimony is oxidized by the fusion with bisul- phate of potassa, but not separated from the lead. rinally, it must be remarked that in treating by this process suli- fifajtices containing sulphide of lead, the amount of lead obtained is always from one to three per cent, too low, because during the roasting the lead is chiefly converted into basic sulphate, which is, indeed, decomposed by the soda, but in consequence of the formation ■of sulphide of sodium some sulphide of lead also results and goes into the slag. The loss can even increase if the fusion is continued too long at a high temperature, because then some lead is liable to be volatilized. Hirsohwald {Berg-u, Buttenm. Zeit. 1876, No. 18) has proposed an apparatus for such cruoible assays, using gas ivnd a bellows ; its arrangement is given in the article cited. The coal furnace used is of graphite or gas coke and of the size of Plattner's coals just mentioned. Lead assays in unlined crucibles can be thus made, according to Hirsohwald. in half the time, and assays in crucibles lined with coal are easily made according to the method just described. The very suitable application of the flame from below, in these crucible assays, may also be used in case of artificial or natural charcoal prisms. For this purpose it is best to use the coal-holder and the platinum wire accompanying it. Figs. 53 and 54, boring the opening for the flame in the middle of the lower face of the prism. Friok's gas blowpipe, Fig. 9, can also bo »sed, being fastened in a suitable manner. In this case, however, the long tube must be replaced by a rubber tube with a mouthpiece. The coal-holder can then be set upon the ring D or E of the blowpipe lamp, Fig. 7. To use the flame of this lamp it must be provided with a circular burner in the centre of which is fixed a small tube with a fine opening for the passage of the air supplied either by the mouth or a bellows. SECOND METHOD. The substances which can be assayed by this method are: — all the compounds containing sulphide of lead mentioned on pp. 217-218; among ores dressed on the large scale, galenas and all lead ores mixed with other metallic sulphides and arsenides; among metal- lurgical products, especially lead matt and plumhiferous cadmia (Ofenbruch), as well as lead slags and Rohsclilacken {raw slags). . The purer lead ores can be assayed at once ; those containing considerable sulphide or arsenide of iron need roasting, also those with considerable antimony. The roasting is done without char- coal dust (antimonial ores require addition of 50 mg. of ferric oxide) in a clay capsule, p. 386, with a feeble heat, until no odor of sulphurous acid or fumes of antimony or arsenic are perceptible. 404 platxxee's blowpipe analysis. One centner of the assay powder (roasted if necessary) is poured into a clay crucible, Pig. 30, p. 24, and the requisite fluxing and reducing agents arc added as follows: 1. Metallic iron in the form of wire, the thickness of a moderately coarse knitting needle; according to the amount of metallic sul- phides present and the proportion of sulphur they contain, the piece employed varies from thirty to fifty milligrams, and it is laid directly on the weighed substance .in the crucible. 2. An alkaline fluxing and reducing agent (Plattner's flux), con- sisting of equal equivalents of anhydrous carbonates of soda and potassa, with borax-glass and starch-powder in the following pro» portions : — 10 parts by weight of carbonate of soda, 13 « « " " « " potassa, 6 " " " " powdered borax-glass, 5 " " " " dry starch-powder. These ingredients are carefully mixed in a spacious mortar and then preserved in a well-closed bottle. If no mortar is at hand the ingredients, when fine enough, can be mixed by shaking them to- gether in a corked bottle. Three hundred milligr. of this easily fusible flux are poured directly upon the substance and the iron in the crucible, and the whole is covered with three heaped spoonfuls of decrepitated common salt, p. 51, or about six hundred milligr. Fifty to eighty milligr. of pure silver in one button are added to- substances containing only a- little lead, in order to collect the latter. During the fusion of the assay, the iron serves to separate the sulphur and arsenic, the latter being, however, generally volatile ; the alkaline carbonates, with the borax, serve to form the slag and dissolve the earthy matters. With such metallic sulphides as are not decom- posed by iron, as well as to take up the greater part of the sulphide of iron formed; the starch acts as a reducing agent, in common with the carbonates of the alkalies, while the salt, being very fluid when melted, and having no tendency to combine with the slag, serves as 'a cover, so that the separate reduced lead buttons can more easily unite into one. The substance to be assayed might be mixed witli the flux, but then little globules of lead are liable to come to the Burface of the slag, and the union into one button is retarded. When, however, the substance consists chiefly of substances that must be slagged off, such a mixture is to be recommended. For the fusion a coal is prepared in the coal-holder, regarding all the details mentioned on p. 18. The crucible is then set on the ASSAY OF MISDEALS COKTAINING LEAD AS SULPHIDE. 405 wire ring without any cover, the perforated charcoal cover is placed above it, and a strong 0. F. directed into the opening a in a horizon- tal direction, so that the point of the blue flame remains just out- side, while, for the most part, only the glowing gaseous products of combustion enter the hollow coal. The crucible must not be touched directly by the flame, or else the high temperature at that Bpot will cause it to be attacked and perfo- rated by the alkalies. The heat spreads quite rapidly when the coal is not too dense, and after blowing five or six minutes at the most, tlie assay is perfectly fused. Even after the first minute the noise caused by the lively evolution of gas from the action of the sub- stances in the crucible can be heard, and so long as this is distinct the blast must on no account be strong, or the evolution of gas will become too lively and cause the charge to overflow. After the noise ceases, however, a strong blast must be kept up for at least one or two minutes, and the point of the flame directed very particularly toward the lowest point of the crucible, if a correct quantitative determination of the lead is desired. After stopping the blast the coal cover is removed and the coal-holder struck on the side with the handle of the forceps, so that the little lead globules which may still be scattered about the border of the crucible, or the surface of the slag, may sink and combine with the main button. The slag should be as fluid as water at this time. The crucible is then lifted out and set on its stand to cool for some minutes, until it can be held in the fingers, when it is carefully broken with the hammer on the anvil, and the lead, with the iron adhering to it, separated from the slag. The lead is then held with the forceps on the anvil so that the iron is on top, and this, which is sometimes surrounded by sulphide of iron in case of very pyritiferous ores, is detached by a few light strokes of the hammer. Any adhering portions of slag are removed from the lead by hammering it gently between moistened filter-paper, after which the button is weighed. In this second process the formation of alkaline sulphides cannot be avoided, and therefore, in spite of the addition of iron, a little sulphide of lead also goes into the slag, and the result is always somewhat too low, as in the first process and likewise in the dry assay on the large scale. If the substance is supposed to be argentiferous, the lead button 406 PLATTNEK'S blowpipe AXALT8IS. ehould be cupelled and the weight of the silver deducted. If the substance assayed consisted of pure galena the silver thus found weighs the same as that obtained by a special silver assay, but it is too little if the substance contains argentiferous pyrites, or other argentiferous sulphides. A trifling amount of sulphide of copper in the plumbiferoua sub- stance goes into the alkaline slag, but if considerable of it is present, or the copper is in the oxidized state, and there is, moreover, a lack of metallic sulphides, more or less copper always goes into the lead. In this case it is necessary to treat the lead with boracic acid, accord- ing to p. 394, and to deduct the weight of the resulting copper from that of the cupriferous lead.* When the substance contains only one to ten per cent, of lead, it is difficult to separate the lead button from the iron, so as to weigh it accurately. In this case fifty to eighty milligr. of silver is added, in small clippings, or in one or several buttons, and the lead combines with this to a button, which is so large that it can be easily separated from the iron. The increase of weight gives the amount of lead. S. Minerals, Ores, and Products containing the Lead in the state of chloride as well as of oxide, free, as slag, or combined with acids. Here are included chloride of lead, as well as combinations of oxide of lead with phosphoric, arsenic, sulphuric, carbonic, acetic, vanadic, molybdic, tungstic, and chromic acids; further, litharge, ab- strich, and cupel bottoms, and all sorts oi plumbiferous glasses. These compounds may, indeed, be assayed according to the first method on p. 399, the roasting being only performed when other metallic sulphates are present, or when metallic sulphides and arsenides are intermingled; the second method is, however, far simpler, and equally reliable. One centner of the substance is poured into a clay crucible, and twenty-five to thirty milligr. of iron wire added in one piece. Three hundred milligr. of the fluxing and reducing agent, p. 404, and twenty- five to thirty milligr. of additional starch-powder, are then mixed directly in the crucible with the substance, with the ivory spoon-handle or the small ii"on spatula. The mixture is then made as compact as * In cases where the presence of considerable antimony necessitates preliminary roasting, and a trifling qnantity of copper may be present, this can be prevented from going into the lead by mixing the roasted assay first with one hundred milligr. of snlphni in the crucible, and heating it to low redness in the square coal, until the blue flame ;«!ases. The oxide of copper formed during the roasting is thus transformed iata culjihide which goes into the slag. THE BISMUTH ASSAY. 40? jtossible by striking the crucible carefully upon the table, and three heaped spoonfuls, or about six hundred milligr. of common salt added as a cover. An addition of fifty to eighty milligr. of pure silver is required for elags and substances containing little lead. The fusion is performed in precisely the same manneras before described. The alkaline flux serves to decompose the lead salts, and, in common with the starch, to reduce the oxide of lead and other reducible ingredients, while it forms, in common with the borax, the necessary slag. The iron serves chiefly to prevent any sulphide of lead from going into the slag, in case it should be formed from sulphate of lead present. If the substances belonging here are not free from a trifling amount of copper, the assay can be sulphurized before charging it with the flux and reducing agent, according to the note on p. 406. C Minerals containing the Lead in the metallic state, combined either with Selenium or with other metals. In this class belong dausthalUe, tilkerodite, zorgite, lehrhachite, altaite, nagyagite, and weissteUur. These minerals can be most simply assayed in an unlined clay crucible. One centner of~ the finely pulverized mineral is mixed directly in the crucible with three hundred milligr. of the fluxing and reducing agent, twenty-five to thirty milligi-. of iron wire added in one piece, as a precautionary measure, the whole compacted by striking the crucible carefully against the table, and then three heaped spoon- fuls of salt added as a cover. The fusion is made just as before. The compounds of lead with selenium or tellurium are decomposed, alkaline selenides or tellurides being formed, and the lead liberated. If the mineral likewise contains metallic sulphides, then sulphides of sodium and potassium are also formed. After the fused assay is cold the crucible is broken, and the separated lead detached from the iron and slag. The lead need only be cupelled in order to determine any silver or gold combined with it. When con- siderable copper is present, the lead button is unavoidably cupriferous and must then be refined to determine the copper. 5. THE BISMUTH ASSAY. Bismuth generally occurs in nature only in the native state, but it is also found in combination with tellurium, as seen in the composi- tion of the bismuthiferous minerals on pp. 236 and 237; also with sulphur, both alone and in combination with sulphides of copper, lead, 408 plattstee's blowpipe analysis. and other metals, and some rare minerals ; likewise in tlio oxidized state, partly free and partly with carbonic, phosphoric, and silicic acids. In metallurgical products it sometimes forms a constituent of cobalt speiss from the manufacture of smalt, and of nickel speiss from the smelting of bismuthiferous nickel ores, etc. In purifying with dilute hydrochloric acid, the impure oxide of tin ore roasted on the large scale, and containing bismuth, which is converted into oxide by the roasting, basic chloride of bismuth is obtaiaed, which is rendered more or less impure by other- substances, as earthy matters, fine particles of oxide of tin, etc. The same salt is obtained in extracting bismuth by tlie wet way from the silver refining hearth. The minerals, ores, and products to be assayed for bismuth can, therefore, be classified thus : A. Such as contain bismuth in the metallic state; either mixed only with earthy substances, or arsenides of cobalt, nickel, and iron; or else chemically combined with tellurium or selenium. B. Those in which the bismuth occurs as sulphide, either alone or chemically combined with other metallic sulphides or arsenides. C. Those containing the bismuth as oxide, free, or combined with carbonic, phosphoric, or silicic acids, etc., and possibly mingled with oxides of copper, nickel, and cobalt, or their salts ; or else containing the bismuth combined with chlorine, A.. Assay of Minerals, Ores, and Products containing the Bismuth in the metallic state, either mixed only with earthy substances, or arseoiaes of Cobalt, Nickel, and Iron; or else chemically combined with Tel- lurium or Selenium. In this class belong all cobalt and nickel ores, dressed on the large Ecale, and containing an admixture of native bismuth; among minerals,, native lismuth disseminated in earthy gamgues, ietrady- mite and joseite ; among metallurgical products, the cobalt and nickel speisses. One centner of the powdered substance is weighed out, and, if necessary, prepared for the fusion as follows : — Cobalt and nickel ores dressed on the large scale and containing these metals combined with 60 much arsenic, that they give a sublimate of metallic arsenic in the closed tube, and therefore contain more arsenic than the combination (Xi, Co) As, must be freed from this excess. When the substance tc be assayed consists of such an ore, the weighed quantity is poured into a clay crucible, which is placed on a proper support, and is to be MINEKALS CONTAINING METALLIC BISMUTH. iOi) subsequently used for the fusion also. The crucible is then put intc a square coal fixed in the coal-holder, and in which a ring of iron wire is substituted for the similarly-shaped platinum wke, p. 40, just as described under the fusion of a lead assay, p. 401. The cruci- ble is then covered with a clay capsule and the whole with a perfo- rated coal cover, the blowpipe flame being directed through the hole in the coal-holder as before described, so as to bring the interior of the coal and the crucible to a dull redness. The excess of arsenic then escapes, and the substance, when rich in metallic arsenides, sinters together more or less strongly.* When the fumes cease to ascend the blast is stopped, the wire, together with the crucible, removed with the pliers, as described in the lead assay, p. 401, and allowed to cool with the cover on, so as to prevent access of air and roasting. After removing the excess of arsenic by this gentle ignition, the assay is, ready for the fusion. When the substance is cold, a piece of iron wire weighing about thirty miUigr. is added, which is indispensable for the thorough de- composition of the sulphide of bismuth and the saturation of the metallic sulphides and arsenides, which cannot be decomposed by the fusion. Further, in order to collect the bismuth separated during the fusion, and to separate it after the fusion from the simultaneously liberated metallic arsenides, and the excess of unaltered iron, so that there may be no mechanical loss of the brittle bismuth, fifty to two. hundred milligr. of pure silver, according to the quantity of bismuth expected, is added in fine clippings or a button, which have been exactly weighed out. During the fusion the bismuth forms an alloy with the silver, and if there is three or four times as much of the latter as of the former, this alloy on cooling is much less brittle than pure bismuth; after deducting the weight of the silver it shows the amount of bismuth, provided no other metals have been reduced at the same time. Lead might be used in place of silver, since one part of bismuth with about four of lead gives a likewise malleable alloy, but the results would be less exact, because with a large proportion of bismuth in the substance so much lead must be added, that several per cent, of it might easily be lost as sulphide in the slag, or by vola- tilization, and the amount of bismuth found would be proportion- ately smaller. • Should copious fumes of arsenic be evolved during the preliminary test in the closed tube, it is well to perform the ignition outsi. Oxides of cobalt and nickel. B. Those consisting of alloys, or metallic sulphides and arsenides with more copper than nickel. A. Assay for Cobalt, Nickel, and, if necessary, Bismuth, in Minerals, Ores, and Products, which contain the Cobalt and Nickel combined with Arsenic, and sometimes with a little Sulphur, but are &ee from Copper. Here belong, among minerals, the compounds of cobalt and nickel with arsenic, mentioned on pp. 197 and 203; among metal iurgical products, the speisses free from copper. With substances containing no bismuth, or where it is not neces- sary to determine the trifling amount of it present, the first opera- tion of fusing the assay with a suitable flux can be performed in two ways : either in a coal crucible, as in the silver assay, or in an onlined clay crucible, as in the lead and bismuth assays. By the latter method the mechanical loss attendant on mixing, wrapping up, and fusing the assay is entirely avoided, and with cobaltiferoua substances containing little or no iron there cannot well be any oxidation of the cobalt during the fusion, while the presence of earthy constituents also does no harm ; on the other hand, it cannot be used when arsenide of cobalt prevails in the assay, on account of ASSAY FOB COBALT, KICKEL, AND BISMUTH. 429 ■the difficult fusibility of this compound, unless some arsenide of iron is added. The fusion on coal or in a coal crucible is performed on one ctr. of the powdered substance, which is mixed in the agate mortar with : 50 milligr. soda, and 15 " borax-glass, ■transferred to a soda-paper cylinder and then treated with a pure, moderate R F., until the flux has become a slag and the metallic particles have united to a button. The soda not only forms an easily-fusible slag with the borax, furthering the rapid union of the metallic parts and the separation of any sulphur, while it takes up some iron as protoxide, but it also prevents the easy oxidation of the cobalt when a pure E. F. is used. 'J'he resulting metallic button is freed from slag by cooling it in water, and then all iron must be removed from it before the Co' As and Ni" As can be formed. The button is therefore fused in a cavity on coal with a moderate K. F., when, if no iron is present, it speedily shows a bright surface and assumes a rotary motion. In this case it is kept fused until the fumes of arsenic cease, when the blast is stopped and the button weighed; the weight gives the sum of the (Co Ni)" As. During the operation, by which any trifling admixture of bismuth is also volatilized, the blast must be just strong enough to keep the button fluid and bright, since it may ■easily spit with too high a heat. If the button contains iron it does not show a bright surface, but is quickly covered with a film of oxide, when borax-glass must be added and the usually trifling amount of iron slagged off, according to p. 434, until the button shows a perfectly bright surface. A little cobalt is unavoidably lost by slagging with the last portions of the iron ; but the iron must be completely removed, or it is impossible to volatilize entirely the excess of arsenic ; the button is then heated alone, as above men- tioned, and the (CoNi)''As weighed. The cobalt is next slagged off, according to p. 435, until finally Xi^ As alone remains. This compound is weighed and the amount of Co" As obtained by difference. If experience is wanting in regard to the proper temperature and the various phenomena of this assay, the resulting button may be again fused with a little borax on coal for a short time, and the melted glass examined, to see whether it is colored brownish by oxide of nickel, or violet from a mixture of some cobalt remaining or only blue from oxide of cobalt. In the latter case the tuttou 430 plattner's blowpipe analysis. must be again weighed and the amounts of cobalt and nickel reck- oned anew, provided that all cobalt is now really separated. When treating smaltite or cobalt speiss, which often contain so much arsenide of cobalt, that one fusion is not sufficient, the blast must be stopped when the borax-glass appears to be saturated in the first fusion, freed from the slag in water, and treated with fresh borax-glass, until all cobalt is removed, .or the glass is again satu- rated. In the former case, that is, when apple.-green spots appear on the surface of the solidified button, the slag is removed and the button weighed; in the other case, the cooled button is covered on the surface with a gray or dirty-yellow film of oxide, and the fusion must be repeated with a third and not too large portion of borax- glass, the operation being continued with fresh, but constantly decreasing portions of borax -glass, until all of the arsenide of cobalt is removed. If the borax-glass, after saturation, were further treated with t^e blue flame, the arsenide of cobalt in the button would indeed grad- ually oxidize, but portions of it would be reduced again from the glass by the reducing action of the glowing coal, and the oxidizing process would only be prolonged. It is therefore better to remove the last of the cobalt with fresh borax-glass. If the assay contains a notable amount of silver, this must be determined and deducted from the arsenide of nickel as sulphide of silver, in which state it occurs in the arsenide, before the nickel can. be calculated. For this purpose the button is fused with enough test lead and some borax -glass on coal, and then cupelled according to p. 369, et seq. The resulting silver is reckoned as sulphide of silver, 100 parts of Ag yielding 114.8 parts Ag' S. When the substance is to be fused in a clay crucible instead of a coal crucible, the weighed amount is placed in it and freed from the excess of arsenic, if considerable, by gentle ignition, according to p. 409, until no more fumes are observed. To the mass, which is gen- erally sintered together, three hundred milligr. of the fluxing and reducing agent are added, without mixing it with the substance, and then a cover of three spoonfuls of salt, as in the lead and bis- muth assays.* The fusion is conducted just as in those assays, and yields a perfectly fluid slag, through which may be seen the button of metallic arsenides at the bottom, when the coal cover is removed. * If cobalt predominates in the substance, 15 to 20 milligr. of arsenide of iron, or some ferric oxide, must be added, as above mentioned. ASSAY rOE COBALT, NICKEL, AND BISMUTH. 431 After breaking open the cold crucible, the button is treated on coal, according to p. 429, when the presence or absence of iron is at once ascertained, and the assay oompleted as there directed. To determine bismuth at the same time, the substance, freed from excess of arsenic, is fused in the clay crucible with the flux and reducing agent, and an addition of iron and silver, as directed for the quantitative bismuth assay, p. 409. The combination of arsen- ides of iron, cobalt, and nickel, which has been more or less broken up in separating the bismuthiferous silver, either between paper on the anvil, or in the steel mortar, is fused on coal, or in a coal cruci- ble, in the K. P., with soda and borax-glass, to a button, which is treated as before. The amount of iron being increased by the ad- dition of the metallic iron, two or more portions of borax-glass are sometimes necessary to remove all the arsenide of iron from the arsenides of cobalt and nickel. B. Assay for Cobalt and Nickel, and, if required, for Lead, Bismuth, or Copper at the same time, in Minerals, Ores, and Products containing Cobalt and Nickel, with perhaps other metals, combined partly with Arsenic and partly with Sulphur. In this class are included, among minerals: cobaltite, glaucodot, danaite, gersdorfflte, ullmannite, syepoorite, linnaeite, miUerife, horiachite, and pentlandite; further, all cobalt and nickel ores dressed on the large scale, and not free from mispickel, iron pyrites, or copper pyrites; among metallurgical products: lead speisses, which contain, besides arsenides of cobalt and nickel, much arsenide of iron and several metallic sulphides ; also niccoliferous and colaltiferous lend matt and Rohstein. Before the fusion these substances must be completely roasted on a clay capsule, according to p. 386; at first alone, but afterward, when they cease to evolve any odor, with fifty to sixty milligr. of carbonate of ammonia, which is rubbed up in the mortar with the roasted assay. The resulting oxides must be converted into arsen- ides by a large addition of metallic arsenic, which can be done in a clay crucible, or in a tube closed at one end. When the conversion of the metallic oxides into metallic arsenides, or the "arsenicizing," can be done outside of the laboratory it is 432 plattner's blowpipe analysis. performed as follows : the roasted powder is mixed in the agate mor- tar with one hundred milligr. of pulverized metallic arsenic* and poured into the clay crucible, which is also to be used for the subse quent fusion. This is set on an iron wire ring in a square coal fixed iu the coal-holder, as described for the fusion of the lead assay, p. 400; the crucible is then corered with a clay capsule and the whole with a perforated coal cover. The coal-holder is kept at some distance from the lamp and the hot products of combustion directed into the interior of the coal, when the crucible becomes so strongly heated that the arsenic begins to sublime and exerts a reducing action on the free metallic oxides and basic arsenates, forming arsenous acid and suboxide of arsenic, and at the same time changing into arsen- ides those metals which have a tendency to combine with it. The crucible is heated to low redness, so as to volatilize the excess of arsenic, as far as this is possible without access of air, and to sinter, or, under certain circumstances, fuse together, the metallic arsenides formed. "When the excess of arsenic is expelled the iron wire with the covered crucible is removed from the coal, as in the case of the melted lead assay, and placed on a stand to cool, with the cover still on. When the arsenicizing must be performed in the laboratory the mixture of ore, etc., with metallic arsenic is placed in the mixing capsule and thence transferred to a perfectly dry glass tube, closed at one end, and gradually heated to glowing over the spirit-lamp. As before, the oxides and arsenates are converted into arsenides, while the excess of arsenic sublimes and condenses in the cool part of the tube. When cold the tube is cut with a file close under the sublimate, broken off, and the metallic arsenides, which generally form a dark, yellowish -gray powder, poured into the clay crucible destined for the fusion, while the tube is cleaned into it with the spatula and brush and the assay charged as will be directed below.f One centner of the finely-pulverized substance to be assayed hav- ing, if it contains metallic sulphides, been roasted thoroughly and the free oxides and basic arsenates thus formed converted into arsenides, the question arises, whether 'the substance contains lead or bismuth ? If this is found to be the case by testing a little of the raw substance on coal, these metals can be separated during the fusion and quanti- tatively determined. It is only necessary, as directed in the bismuth assay, p. 409, to add to the arsenides in the crucible a piece of iron wire * A less quantity is not admissible, as the desired result might not then be at- tained owing to the volatility of the arsenic. f To avoid mechanical loss the arsenicizing can be done in a glass tube, Fig. 85, p. 439. ASSAY FOR COBALT, NICKEL, LEAD, ETC. 433 weighing about twenty milligr. and an exactly weighed amount of silver, from fifty to one hundred milligr., so that an alloy of bismuth or lead and silver is obtained during the fusion, from the weight of which the amount of lead or bismuth can be ascertained. If the substance contains none of these metals, or only an unimportant amount, which can be volatilized during the separation of the arsenide of iron and the excess of arsenic on coal, p. 439, the iron and silver are omitted, and the following substances at ouce added to the substance already in the crucrble : 300 milligr. fluxing and reducing agent. 3 spoonfuls of salt as a cover. The fusion is conducted as in the lead assay, p. 405, and the heat must be rather strong toward the end, so as to collect the arsenide to one button.- After continuing the proper temperature for five or six minutes the arsenides collect in a round button at the bottom, while the earthy matters and the oxides which do not separate in the metallic state are completely slagged off. If iron and silver had been added to sep- arate any lead or bismuth, the iron passes into the metallic arsenides, and the lead or bismuth forms an alloy with the silver, which joins with the arsenides to one button, but only forms an adherent part of it, and can easily be mechanically separated, as has been fuUy de- scribed in the bismuth assay, p.- 409. If the substance contains more nickel than cobalt the metallic arsenides unite very easily to a button, but otherwise, the union is more difficult in proportion as the cobalt exceeds the nickel. A combination of arsenides of iron and cobalt, however, also fuses easily, and as these two "arsenides can be separated without any important loss of cobalt, the evil mentioned can be remedied by combining the arsenide of cobalt with a corresponding amount of arsenide of iron. This is done by adding to the roasted substance which is to be arsenicized, according to the cobalt present, ten to twenty milligr. of iron, in case none was to be added to separate bismuth or lead. When the substance seems very poor in nickel and cobalt, so that it would be difficult to obtain a perfectly fused button, some collect- ing agent must be employed, which can be easily slagged off from the arsenides of cobalt and nickel. Arsenide of iron serves here also. Fifteen to twenty milligr. of arsenide of iron, formed directly in a clay crucible from iron filings and metallic arsenic, are added to the substance to be fused, or when the substance is arsenicized, ten to fifteen milligr. of iron filings are added also, in order that the neces- 434 plattner's blowpipe analysis. gary amount of arsenide of iron may be present already. The filings can be omitted when the roasted substance contains much oxide of iron, which secures the formation of arsenide, but a bit of iron and the necessary amount of silyer must always be added when the lead or bismuth is to be determined- When the fusion has been successfully accomplished, i. e., when the slag is perfectly fluid, and the melted button can be seen at the bot- tom, unless the slag contains too much protoxide of iron, or coal, which finally oxidizes at the expense of the carbonic acid of the alka- lies, the crucible is set aside to cool on its stand ; otherwise the assay must be kept at a melting heat for some time longer. When cool the crucible is broken, and the button carefully separated from the slag on the anvil. If silver has been added, the alloy is separated from the metallic arsenides between paper, or in the steel morfcar, freed from adherent slag with borax, p. 410, and the lead or bismuth determined by the increase m weight. The arsenides and the slag last removed from the alloy are fused in the E. F. with soda* ami the metallic arsenides separated, as given on p. 434. The substance is seldom free from nickel, and then the button entirely disappears when treated with fresh portions of borax -glass; if otherwise, there remains a button which can be recognized as arsenide of nickel, either by the signs given on p. 425, or by the last addition of borax, even when it only weighs one milligramme. If everything dissolves in the borax, the cobalt is to be calculated from the weight last noted down, according to p. 427; but if a little button of arsenide of nickel remains, it must be weighed, and the cobalt reckoned from the diflference. When the substance also contaius copper, this will be present in the arsenical compound, which is then separated as follows : first, the arsenide of iron is removed with borax, according to p. 425; any zinc or antimony present is also volatilized at the same time; the excess of arsenic, with any remaining antimony, is volatilized next, and the arsenide weighed, after which the cobalt is removed, leaving a com- pound of arsenides of nickel and copper, which is fused with eighty to one hundred milligr. gold, the nickel separated with salt of phos- phorus, according to p. 427; and the cupriferous gold weighed, after which the amounts of the metals can be found from the results of the respective weighings.f * This second fusion, to get the arsenides in one button, can be made in a coal crucible, or in a clay crucible ; in the latter case 3 etrs. of the fluxing and reducing agent are laid on the fragments of arsenides, with the slag, and a salt cover is also employed. + MilQSter (translated by Schweder, Berg- u. Huttenm. ZeU., 1877, p. 118) has proposed to carry out the cobalt and nickel assay in a somewhat different way, for a completely equipped laboratory. The variations refer especially to roasting and fusing the assay, and to separating the copper. ASSAY FOE COBALT, NICKEL, LEAD, ETC. 435 The wet way, although more complicated, may also be used for determining the copper and nickel after removing the cobalt. The button is dissolved in a test-glass with a mixture of about three parts dilute sulphuric acid and one part nitric acid, by warming it, and the copper and arsenic are precipitated with sulphuretted hydrogen.* The sulphides are separated by filtration from the solution contain- ing all the nickel, washed with sulphuretted hydrogen water, and the clear solution warmed in a porcelain vessel over the spirit-lamp until all the sulphuretted hydrogen is driven off. Some sulphide of arsenic generally separates, which must be removed by a second filtration, and then the protoxide of nickel is precipitated with not too concen- trated a solution of potassa. The precipitate is collected and washed with hot water on a filter, dried, ignited, and reduced to metallic nickel. For this purpose the dry precipitate and the filter ash are mixed with — 50 milligr. soda, 50 " borax-glass, and a weighed gold button, and treated in a soda-paper cylinder on coal with the E. P., until all the nickel is reduced and combined with the gold ; the amount of nickel is ascertained from the increase in weight of the gold button. To determine the copper, the washed sulphides are dried and gradually heated in a deep porcelain vessel, p. 43, Fig. 62, over the spirit-lamp, so strongly that all the sulphide of arsenic volatilizes and only sulphide of copper remains. To avoid loss, the dry precipitate is first transferred to the vessel and then the filter ash added. The heat may be continued until most of the sulphide is converted into sulphate of copper, and when the odor of sulphurous acid ceases, six to eight times as much dry bisulphate of potassa is added, brought to fusion, and kept so at a moderate red 'heat until all the copper ia dissolved. It is well to cover the vessel with a piece of platinum foil during this operation. The cooled mass is then dissolved by placing the vessel with its contents in another porcelain vessel half full of water and heating it well over the lamp, after which it ia filtered, if necessary, the solution brought to boiling heat, and the * The wet way must be adopted if the amount of copper ia at all considerable, becanse the dry way with the use of gold becomes very inaccurate. 436 plattnee's blowpipe analysis, copper precipitated by not too concentrated a solution of potassa. It is then collected on a filter, well washed with hot water, dried, ignited, and reduced as just directed for the nickel, but using only 25 milligr. of borax-glass. When one of the substances of the second class contains a notable amount of silver, this must be deducted, either as sulphide of silver from the arsenide of nickel, if the substance was fused in the raw state without addition of iron or silver, or as metallic silver from the reduced bismuth, if the substance was roasted, arsenicized, and fused with iron and silver, as directed in the bismuth assay, p. 410. Example. — ^A lead speis8 from the Freiberg Smelting Works, enriched by concentra- tion for nickel and cobalt, but still very impure, was found by qualitative tests, p. 342, to consist of arsenides of iron, nickel, and cobalt, and sulphide of copper, lead, zinc, and antimony ; the trifling amount of silver was neglected. One ctr. being roasted, arsenicized, and fused with the flux and the addition of about twenty milligr. iron and ninety milligr. silver, in a clay crucible, yielded a button one half of which was an alloy of silver and lead, while the other half consisted of metallic arsenides. Being detached in the steel mortar, and properly freed from slag, the alloy weighed 93.5 milligr., and, therefore, the ninety milligr. silver had taken up 3.5 milligr. lead. The arsenides and the slag, properly treated and freed from arsenide of iron and the excess of arsenic, yielded a combination of m (Ni, Co)^ As + n Cu' As, which weighoil 61.5 milligr. After removing the cobalt the button weighed 48.5 milligr., so that thir- teen milligr. C02 Aa were removed, giving — '^^ — = 7.95 milligr. cobalt. If the speiss had been iree from copper the nickel could now have been also determined, but it was really necessary to fuse the button with a gold button weighing 85.6 milligr., when it was treated as directed on p. 427, and yielded a button weighing 93.9 milligr. The speiss, therefore, contained 8.3 milligr. copper. To determine the nickel, this copper was reckoned as Cu" As, and subtracted from the combination of arsenides of nickel and copper that had been found to weigh 48.5 milligr. The method of calculating the CusAs is as follows: 71.7 parts Cu, and 28.3 parts As form 100 Cu« As, the 8.3 100 X 8 3 milligr. copper in the gold correspond, therefore, to — 7~s~~ ~ 11.57 milligr. Cu> As, which was taken at 11.6 milligr. and subtracted from 48.5, leaving 86,9 milligr. 60.9 X 36.9 „„ . .,,. . , , Ni' As, or — — — = 22.4 milligr. mckel. The speiss, therefore, contained 22.4 per cent, nickel, 7,3 " cobalt, 8.3 '' copper, 5.5 " Ipad. By making the assay according to the foregoing directions, when the necesMi; practice has been acquired, the whole examination can be made in about three hoor& and the results obtained will leave little to be desired, unless analytical accuracy Is absolutely necessary. ASSAY OF MIXTURES OF METALLIC OXIDES. 437 O. Assay for Cobalt and Nickel in Minerals, Ores, and Products con- taining Nickel and Cobalt in the oxidized state, combined with arsenic or arsenous acids, or other metallic oxides, and sometimes also water. This class includes, among minerals and ores, Meberite, erythrite, earthy cobalt bloom, lavendulan, morenosite, emerald nickel, annaber- gite, rSttisiie, genthite, pimelite, earthy cobalt, and cobalt and nickel ores roasted on a large scale ; among products, speisses roasted on a large scale, smalt, cobaltiferous and niccoliferous slags which fall from refining the slags and from other smelting operations and con- tain very little or no copper. Erythrite, cobalt bloom, and annabergite (nickel ochre) contain more arsenic than is required to convert all the cobalt and nickel into (Co, Ni)' As during the reducing fusion to unite them into one button, from which the amount of each of these metals may then be determined; the arsenide of cobalt reduced from these cobalt com- pounds is, however, so hard to fuse that it can only be melted to a button in the clay crucible with great difficulty, unless arsenide of iron is added. Directly formed arsenide of iron must therefore be added, or the substance in question must be mixed with fifteen to twenty milligr. iron filings and arsenicized, p. 433. Cobalt ore, roasted in the large way, and the vitriols, after being well roasted in- a clay capsule with charcoal powder, must be similarly prepared for the fusion. The other minerals and the nickel ores and speisses roasted on a large scale can be arsenicized at once. Smalt and slags, which some- times contain oxide of lead and suboxide of copper, must be mingled in the finest powder with ten to fifteen milligr. iron and then arseni- cized. One ctr. of the perfectly dry powdered substance having been, if necessary, roasted and arsenicized, while in case the cobalt pre- dominates, or the substance is a slag or ore poor in cobalt and nickel, provision has been made for the formation of arsenide of iron, not only to secure a fusible combination of arsenides, but, in case of pool substances, also to collect the metals in question to a single button, it is charged in a clay crucible with — 300 milligr. fluxing and reducing agent, which is pressed down somewhat and covered with — 3 heaped spoonfuls of salt. 438 plattner's blowpipe ajtaltsis. If the substance contains oxides of bismuth or lead, the latter some- times occurring in many slags, a bit of iron wire and a weighed quantity of silver is added to it, before putting in the flux, p. 409, to effect the separation of those metals from the metallic arsenides. The fusion is performed in a manner quite similar to that of sub- stances of the first and second class; and the separation of the silver containing lead, or bismuth, from the metallic arsenides is carried out in the usual manner, as also the separation of the arsen- ides from one another. When slags contain trifling amounts ol cobalt and nickel these cannot be deter- mined in 100 milligr. by the above method alone. Either a larger quantity must be decomposed in the wet way by known methods and the separated oxides, possi- bly containing iron, further treated according to the next section, or recourse must be had to the muffle. For this purpose several grammes of the flnely powdered substance are mixed with one half as much arsenic, the mixture placed in an assay crucible, 20 to 25 per cent, of iron arsenide added (this is prepared by fusing to- gether flnely divided iron and metallic arsenic), and, as in other crucible assays, three times as much fluxing and reducing agent added, with a salt cover. There results a regulus consisting chiefly of iron arsenide, with all of the cobalt and nickel. The iron arsenide is slagged off with borax in a clay scorifler in the mufBe until a button is obtained which can be handled B. B. D. Assay of lUiztures of Metallic Oxides consiating especially of ozldeB of Cobalt or NickeL In this class belong the oxides of cobalt and nickel prepared in the large way ; the former being not always free from nickel, while the latter is seldom quite free from cobalt ; both also contain frequently trifling admixtures of other metallic oxides and earthy matters. To determine cobalt and nickel in these oxides, which generally occur in the ignited state in commerce, one to two ctrs. are first heated gradually to incipient redness in a closed tube or a matrass over the spirit-lamp, to drive off any trifling amount of mechanically com- bined water, the moisture is removed from the tube with filter-paper, and the cold oxide then poured into the mortar and pulverized, unless already fine enough. Fifty milligr. of this prepared oxide are then arsenicized and fused to form a button of metallic arsenides ; both of these operations may be performed variously, according as the arseniciing must be done within the laboratory, or may be done outside. It is better to use fifty than one hundred milligr. for an assay, because if cobalt prevails its oxide cannot be so easily treated, while its arsenide is less fusible and also more easily oxidizable than that of nickel. If done without the laboratory the fifty milligr. of oxide are placed in the clay crucible to be subsequently used for the fusion, and then one hundred milligr. of powdered metallic arsenic are mixed thor- oughly with it. If the oxide consists chiefly of protoxide of nickel, or a mixture of protoxide of nickel and oxides of cobalt, in which the former prevails, the resulting arsenides can easily be melted to one ASSAY OF MIXTUEES OF METALLIC OXIDES. 439 button during the fusion in the crucible ; if, however, oxide of cobalt prevails, the resulting arsenides melt with difficulty, and about fifteen milligr. of iron filings must be added, so as to form arsenide of iron, which produces a fusible combination with the arsenide of cobalt in the subsequent fusion. The arsenicizing is performed just as de- scribed on p. 432, and if a stronger heat than necessary was employed toward the end, the metallic arsenides, if easily fusible, may be melted to a button. After cooling in the covered crucible, the arsenides are charged with three hundred milligr. flux and reducing agent, which is poured upon them, and then covered with three heaped spoonfuls •of salt, after which they are fused according to p. 433. Another method of arsenicizing, with which the fusion of the me- tallic arsenides formed is at the same time combined, consists, accord- ing to Fritzsche, in treating fifty milligr. of the oxides, mixed with one hundred milligr. arsenate of potassa and thirty milligr. borax- glass,* in a soda-paper cylinder in a coal crucible with the E. F., until the arsenides formed by the liberated^ arsenic have united to a button and the carbonate of potassa produced has sunk with the borax into the coal. This should be done outside of the laboratory. Small ad- mixtures of metallic oxides, which are neither converted into arsen- ides nor volatilized, remain in a divided state on the crucible without exerting any injurious effect on the union of the metallic arsenides. When the arsenicizing must be done in the laboratory another method should be adopted, so that the fumes of arsenic cannot escape. Fifty milligr. of the oxides mixed with one hundred milligr. powdered metallic arsenic are placed in a glass tube closed at one end, and heated, as described for ores, etc., p. 433, over the spirit-lamp, until the sublimate of arsenic ceases to increase; or, to avoid all mechanical I /^ ^°^®» *^® mixture is inclosed in a soda-paper I //JT cylinder, made of a strip of fine filter-pa- ^^^_ y // per forty-five millim. long and twenty mil- ^^^y ^ JA lim. wide, ae in the silver assay, and placed ^^^^ / ^ in a tube, eighty to ninety millim. long and ^B if/M about ten millim. wide, closed at one end, as ^B #Jr shown in Fig. 85, a. A roll of ordinary ^B Ms filter-paper is then inserted as far as I, to ^V Mm ^^^ absorb the moisture evolved from the char- c^^ ^^^Hred soda-paper, and the assay is gradually ^^ ^^^Hheated in the spirit flame to redness, while Mm ^^^|the tube is occasionally turned, to prevent ^^^ ^^^|the charring paper from adhering to the \ ^^ FiK. ssMi^B^glass. It is kept in this condition until the * If cobalt predominates about 15 milligr. of iron filings are also added. 440 plattker's blowpipe akalysis. sublimate, c, ceases to increase.* By carefully heating it at first the paper is charred without opening in any part, or adhering to the glass, and therefore prevents all mechanical loss. The fusion of the metallic arsenides, obtained in one way or another, to a button is performed in a clay or coal crucible, p. 428. While the arsenides, formed in either way, are fusing to a button, arsenic still volatilizes, until the remaining compound corresponds nearly or quite to the composition (Ni, Co)' As, provided there is no iron present; the fluxes either sink into the coal or combine to s transparent slag, according as the oxides assayed are free from or contain other metallic oxides. When the fusion is performed in a coal crucible it is well to add half a spoonful of neutral oxalate of potassa and treat the assay further with the R. F., before removing the metal- lic button, as this causes all the slag to sink into the coal, leaving the button quite free. With the aid of a glass it may easily be seen Vhether any little buttons are scattered about, and if any one is found, which is seldom the case, it is (detached with the point of the knife, rolled up to the main button, and at once fused with it in the R P. In sej^arating the arsenides now formed the first question is, again, whether the button contains arsenide of iron or not ? The manner in which this is ascertained and the iron separated is given on p. 439. The nickel and cobalt are then also determined by the process already described. The methods heretofore described are advantageously used in the analysis of niccoliferous apd cobaltiferous substances. The other constituents of the assay having been separated by the known methods and the oxides of cobalt and nickel precipitated together, they are washed, ignited, and weighed. After being then pulverized and again ignited, fifty milligr. of them are arsenicized, which should be done in a clay crucible if possible, because then there can scarcely be any mechanical loss, and after being fused to a button they are separated, according to p. 435, and the percentage of cobalt and nickel or their oxides thus ascertained. * The sublimate adhering firmly to the tube is best detached, after taking out the assay, by simply pushing through the tube another tube open at both ends. If the soda-paper contains too much soda and a strong heat has been used at the beginning, the assay often sticks to the glass, but it can be detached by gentle pressure with a splinter of wood or awlre. MINERALS COlirTAINIlfO MOBB COPPEE THAK NICKEL. 441 E, ARsay of Minerals and Products consisting of alloys, or arsenidei and sulphides, in which there is more Copper than NickeL This class includes among minerals : hreithauptUe ; among metal- lurgical products : niccoUferous and coMtiferous Hack copper, similar copper matts and slags, which are rich in suboxide of copper; among artificial products : Qerman silver, or packfong, tutenag, and similar alloys. These substances cannot be quantitatiTely examined for cobalt and nickel according to the method giyen under A. to D., since they con- tain too much antimony and copper. In case of alloys of nickel and cobalt with antimony, one hundred milligr. are dissolved in nitric acid, the solution filtered from the res- idue of oxide of antimony, and the oxides of cobalt and nickel pre- cipitated with potassa, collected on a filter, washed, dried, ignited in the platinum capsule, and the ignited oxide, which may contain other metallic oxides with a little antimonic acid and oxide of antimony, arsenicized according to one of the methods on p. 438, et seq. They are then fused and treated for cobalt and nickel, which are deter- mined according to p. 440. Products containing more copper than nickel must likewise be dissolved in nitric acid, or if necessary in aqua regia. When the amount of nickel and cobalt is supposed to be very small, more than one hundred milligr. are taken, and slags must be very finely pul- verized. From the solution, copper, lead, antimony, etc., are pre- cipitated by sulphuretted hydrogen, the solution filtered, and the precipitate washed with sulphuretted hydrogen water, which is added to the solution, and the whole evaporated until it has no odor of that gas; it is then heated to boiling, any protoxide of iron present converted into sesquioxide by adding a little nitric acid, and the metallic oxides precipitated with potassa. If the solution of the metallic oxide in aqua regia contained arsenic acid, this is partially precipitated in combination with protoxide of nickel and cobalt, but does no harm. The precipitated oxides are collected on a filter, washed with hot water, dried, ignited, and arsenicized, and the result- ing arsenides fused and treated for cobalt and nickel. If the copper, lead, etc., are to be determined, the precipitated sul- phides are dried and gradually heated to redness in a thin porcelain capsule, so as to expel the excess of sulphur, sulphide of arsenic, and most of the antimony, after which they are fused with bisulphate of potassa in the same capsule. When the resulting Bulphates are 442 PLATTlfBK'S BLOWPIPE ANALTSIS. treated with hot water the sulphate of lead remains behind, bat the sulphate of copper goes into solution, and, after filtration, can be precipitated as oxide with potassa. If pure, the sulphate of lead and the oxide of copper may then be dried,' ignited, and weighed; or they may be determined by reduction assays ; for copper, according to p. 391, and for lead, according to p. 406, et seq. 8. THE ASSAY FOR MERCURY. Mercury occurs chiefly free, or as sulphide {cinnabar), which is the usual subject of assays. If free, simple distillation is em- ployed ; if combined with sulphur or chlorine (as in amalgamation products), decomposing agents are also needed. For blowpipe assays soda and litharge are best. (Biewend has proposed metallic copper). a. Domeyko's method for sulphides. — This method is given in the Beig-u. Huttenm. Zeit., 1845, p. 435. In a glass tube closed at one end. Fig. 86, 16 to 18 cm. long and 6 to 7 mm. in diameter, bent to form a little retort, the short arm about 3 cm. in length, is put an intimate mixture of 0.5 grm. of the assay substance with 0.75 to 0. 8 grm. of finely powdered litharge, and the lower end is gradually heated over the spirit-lamp, provided with a chimney, until the whole mass is fused and the glass begins to soften. The moisture that may be present condenses in the middle of the tube, while the mercury will settle as a thin film, sometimes scarcely perceptible, upon the sides of the glass. When all of the mercury has been sublimed, the tube is carefully heated so as to concentrate the mer- cury, as much as possible, to a ring at i, the tube is allowed to cool, cut off with a file close to the ring, and the mercury then brushed together to one drop and transferred to a weighed capsule. b. Method of Kiistel. This method is given in the Polytechn. CentralU., 1874, p. 464. Of poorer ores, with a few per cent, of silver, 100 mgr. are taken; of richer ores, 50 mgr. With the aid of a long, smooth paper strip THE ASSAY FOK MERCUKT. 443 the ore is placed in the lower end, a, of a tube, Fig. 87, and upon it is put a three- or four-fold volume of perfectly dry soda I. Finally, a spiral of thin gold foil, of 300 to 400 mgr. in weight, exactly weighed. The tube is heated in a horizontal position, at the closed end, over a spirit-lamp, and afterwards for a few minutes is heated with the blowpipe flame, so that the mercury may bo entirely volatilized and may combine with the gold. Any globules of mercury which may condense on the tube are gathered by rolling the gold spiral here and there. The spiral is then with- drawn by means of a wire and weighed. Should any water condense on the gold the latter is dried a short time in a glass over boiling water. When the mercury is combined with chlorine, as in amalgama- tion residues, soda must also be used (about five volumes) because chloride of mercury is not decomposed by oxide of lead. It is best to employ Kiistel's method. Neither of these methods is suitable for the hepatic cinnabar of Idria, containing idrialite, because this volatile compound f scapes with the mercury. APPENDIX. M. Websky {Bergwerksfreund, neue Folge, Bd. I, Lief. 1) has proposed to determine quantitatively various elements by convert- ing them into constant compounds with metals, especially with eilver, and estimating the amount of the metal in the compound by means of the blowpipe. A simple calculation will then give tlie proportion of the substance sought. For details of the methods reference is here made to the article cited. INDEX OF MINERALS. Acanthite, 264(269) Acicular bismuth, 318 Acmite, 107 Actinolite, 133 Adamite, 310 (314) Adularia, 103 ^girite, 107 ^schynite, 163 (154) Agalmatolite, 103 Agate, 317 AgricoUte, 337 Aikinite, 318 (326) Aimifibrit, 172 Alabandite, 171 (175) Albite, 106 Algodonite, 346 (253) Alipite, 304 Alisonite, 318 (235) Allanite, 165 (168) AUemontite, 284 (389) Allochroite, 119 Allopliane, 140 AUuaudite, 180 (190) Almandite, 182 Altaite, 217 (223) Alum, ammonia, 118 magnesia, 131 manganese, 173 potash, 101 soda, 106 Alumian, 139 (141) Aluminite, 139 (141) Alunite, 101 (142) Aluriogen, 139 (142) Amalgam, 360 (262) Amazon stone, 102 Amber, 311 (313) Amblygonite, 109 (143) Amethyst, 317 Amianthus. 133 Amoibite, 303 Araphibole, 132 Analcite, 107 Anatase, vide Octahedrite, 279 (381) Andalusite, 139 Andesite, 107 Andrewsite, 180 Anglesite, 318 (227) Anhydrite, 117(131) Ankerite, 118 Annabergite, 203 (208) Annivite, 247 (255) Anorthite, 120 Antbopbyllite, 133 Antbosiderite, 181 (194) Anthracite, 311 (312) Aniinun-arsennickelglam, 203 (307) Antimonial silver, 364 Antimony, 284 (389) Antimony ochre, 384 (390) Apatelite, 179 (189) Apatite, 117 (123) Aphthitalite, 101 Apjohnite, 173 Apiome, 119 Apopjiyllite, 103 Araeoxene, 219 Aragonite,' 118, (117) (124) Ardennite, 295 Arfvedsonite, 107 Argentite, 264 (369) Argentopyrite, 265 Argyrodite, 265 (271) Arkansite, 379 (381) Arquerite, 260 (263) Arseneisensinter, 180 Arsenglane, 300 Arsenic, 300 Arsenic silver, 264 Arsenical antimony, 284 bismuth, 300 (302) pyrites, 187 Arseniosiderite, 180 (192) Arsenolite, 301 (305) Arsenopyrite, 178 (187) Asbestos, 132 Asbolite, 171 Asmanite/ 317 445 446 INDEX OF MINERALS. Asphaltuin, 311 (313) Astrophyllite, 279 Atacamite, 247 (256) Atelestite, 237 AuerbacUite, 160 (163) Aagite, 119 Auricbalcite, 210 (214) Automolite, 210 (215) Autunite, 243 (245) Aventurine, 317 Axiiiite, 130 Azurite, 348 (357) Babingtonite, 119 Barite, 113 (113) ■ Barnbardite, 346 (254) Baryta mica, 102 Barytes, 113 Barytocalcite, 113 (114) Barytocelestite, 113 (113) Basanoinelan, 181 Bergholz, 181 Bergmannite, 107 Bertblerite, 384 (289) Beryl, 146 (147) Berzelianite, 246 (353) Berzeliite, 118(125) Beiidantite, 180 (191) Beyricbite, 203 (207) Bieberite. 197 (201) BindUeimite, 320 (331) Binnii, 225 Binnite, 247(255) Biotite, 102 Bismite, 237 (241) Bismutb, glance, 236 gold, 276 native, 236 (240) nickel, 203 ocbre, 237 Bismuthinite. 236 (240) Bismutite, 237 (241) Bismutoferrite, 237 Bismutosphserite, 237 Bituminous coal, 311 (313) Black-band, 311 (812) Black manganese, 171 Bleiniere, 220 Bleioxyjodchlorid, 318 Bleuchweif. 217 (234) Blende, 209 Bloedite, 106 Bodenite, 150 (157) Bog iron ore, 179 Bohnerz, 179 Bole, 140 Bolivianite, 365 Boltonite, 181 Boracite, 181 (136) Borax, 106 (816) Bordosite, 260 Bornite, 246 (253) Botryogen, 179 (189) Botryolite, 120 (129) Boulangerite. 317 (234) Bournonite, 218 (226) Bowenite, 182 Bragitp, li9 Branchite, 811 Braunite, 171 (115) (175) Breitbauptite, 203 (206) Breunerite, 131 Brevicite, 107 Brewsterite, 113 (115) Brittle silver ore, 264 Brocbantite, 247 (356) Bromlite, 112(114) Bromyrite, 266 Brongniardite, 265 Bronzite, 132 Brookite, 279 (281) Brown coal, 311 (813) Brown spar, 118 Brncite 131 (133) Brusbite, 118 Bucklandite, 119, 165 Bunseiiite, 203 Buratite, 210 (214) Bustamite, 173 Cacbolong, 133 Cacoxenite, 180(191) Calamine, 210 (315) Calaverite, 376 (378) Calcioferrite, 180 (190) Calcite, 118 (123) Caledonite, 218 (338) Calomel, 260 (363) Campylite, 219 Cancrinite, 107 Canfieldite, 265 Cantonite, 246 Carminite, 180 (192) Carnallite, 101 (133) Carnelian, 817 Carpbolite, 140 Carrollite, 197 (201) Cassiterite, 233 (235) Castorite, 109 Cat's-eye quartz, 317 Catapleiite, 160 (162) Celadonite, 181 Celestite, 116 Cerargyrite, 365 (271) Cerin, 165 (168) Cerite, 165 (168) Carol! te, 132 Cerussitp. 219 (229) Cervanlite, 284 (290) Ceyloiiite, 133 (138) Cbabazite, 120 Cbalcantbite, 247 (256) INDEX OF MINERALS. 447 Chalcedony, 317 Chalcoclte, 246 (353) Calcomenite, 348 (259) Chalcopljyllite, 248 (258) Chalcopyrite, 346 (255) Olialcosiderite, 180 Clialcostibite, 217 (255) Calcotrichlte, 247 Chamolsite, 181 Chiastolite, 139 Childrenlte, 180 (191) CUilenlte, 264 Chiolite. 106 (141) Chiviatite, 218 (237) Cbloauthite, 197, 203 (207) Chloropal, 181 Chlorophseite, 181 Chlorospinel, 133(138)' Chodneffite, 106 Chondrarsenlte, 172 Chondrodite, 133 (137) Christopbite, 209 CUrome garnet, 119 (300) Cbrome ocbre, 299 Chromglimmer, 102 Cbromlc iron, [ .„g ,.gQ. Cbromite, j-i'JU»a) Chrompicotite, 179 Cbrysoberyl, 146 (149) Cbrysocolla, 248 (259) Cbrysolite, 131 Cbrysoprase, 317 Cbrysotile, 133 Cimolite, 140 Cinnabar, 260 (263) Cinnamon stone, 119 Citrine, 317 Claudetite, 301 Claustbalite, 217 (223) Claustbalite (cobaltic), 197 Clay-ironstone, 179 (189) Olayite, 318 (325) Clinocblore, 132 Clinoclasite, 248 (358) Clintonite, 133 Coal, 311 Cobalt pyrites, 197 Cobaltite, 197 (200) Coccinite, 260 Coeruleolactite, 139 Colemanite, 118 (124) Collopbanite, 118 Colopbonite, 119 Coknubite, 181 (194) Common salt, 105 Conarite, 203 Condurrite, 246 (353) Conicbalcite, 248 (259) Copiapite, 179 (183) Copper, native, 24B (253) glance, 246 Copper nickel, 202 pyrites, 246 uranite, 243 vitriol, 247 Copperas, 179 Coquimbite, 179 (189) Curallinerz, 260 Cordierite, 133 Corneous lead, 318 Cornwallite, 348 (358) Coronguite, 330 Corundum, 138 (141) Corynite, 303 Cosalite, 218 Cotunnite, 218 (327) Coupbolite, 130 Covellite, 346 (253) Crednerite, 171 (176) Criclitonite, 181 Crocidolite, 107 Crocoite, 219 (339) Cronstedtite, 181 Crookesite, 246 (353) Cryolite, 106(140) Cryptolite, 165 (167) Cubanite, 247 (255) Cummingtonite, 172 Cupreous manganese, 171 (176)' Cuprite, 247 (256) Cuproiodargyrite, 266 Cuproplumbite, 218 (235) Cuprotungstite, 248 (359) Cyanite, 139 Cyanocbroite, 247 Cyanotricbite, 247 Damourite, 102 Danaite, 178 (188) Danalite, 146 (148) Danburite, 120 (129)i Datolite, 130 (139) Davyne, 107 Decbenite, 219 (230) Degeroite, 181 Delvauxite, 180 (190)' Descloizite, 319 (230) Deweylite, 133 Diadocbite, 180 (190> Diallage, 119 Dialogite, 173 Diamond, 311,(313) Diapborite, 265 Diaspore, 138 (141) Dicbroite, 132 Digenite, 346 (353) Dibydrite, 248 (257) Diopside, 119 Dioptase, 348 (259) Dolomite, 118 '134) (136) Domeykiie, 240 (252) Doppleiite, 311 448 INDEX OF MINERALS. Dufrenite, 180 (190) Dufrenoysite, 317 (325) Durangite, 139 (192) Dyscrasite, 264 (268) Dysluite, 310 Earthy cobalt, 171 (176) Earthy cobalt bloom, 198 (203) JEdingtonite, 113 (115) Egeran, 119 Ehlite, 348 (257) Msenniere. 179 Eisenrose, 181 Eisensinter, 180 Elaeolite, 106 Elaterite, 311 Electrum, 275 Eliasite, 343 (344) Embolite, 265 Embrithite, 217 Emerald, 146 Emerald nickel, 303 Emery, 138 Emplectite, 236 (241) Enargite, 246 (239) Enstatite, 133 Eosite, 219 Epiboulangerite, 217 Epidote, 119 Epigenite, 347 (256) Epistilbite, 130 Epsomite, 131 (134) Erdharz, 311 Erinite, 348 (358) Erythrite, 198 (302) Essonite, 119 Eucairite, 264 (269) Euchroite, 248 (258) Euclase, 146 (147) Eucryptite, 109 Eudialyte, 160 (161) Eulytite, 237 (342) Eupyrchroite, 123 Eusyncbite, 219 Euxenite, 150 (154) Evansite, 139 (143) Fahlerz, 246, 347 Famatinite, 246 (254) Fassaite, 119 Faujasite, 107 Fayalite, 181 Feather ore, 318 (224) FelsSbanyite, 139 (141) Ferberite, 181 Fergusonite, 149 (153) Ferrostibian, 173 Fibroferrite, 179 Fibrolite, 139 Fichtelite, 311 Fireblende, 265 Fire-opal, 317 Fischerite, 139 (143) Flint, 317 Fluocerine (167) Fluocerite, 165 (167) Fluorspar, ) ^^r, fiau Fluorite, ^ ^i^' C-'"^) Forsterite, 131 Fowlerite, 173 Franckeite, 233 (235) Franklinite, 171 (176) Freieslebenite, 365 (271) Frenzelite, 336 Friedelite, 182 Fuchsite, 103 Gadolinite, 150 (157) Uahnite, 310 (315) GSe,i217(334) Galenobismutite, 337 Garnet, 119, 133, 182 Garnierite, 204 Gay-Lussite, 106 (134) Gehlenite, 119 Gelbeisenerz, 101, 106 (190) Gelberde, 181 Genthite, S04 Geocrouite, 217 (224) Gersdoffite, 203 (207) GMsit, 139 (143) Gibbsite, 138 (141) Gieseckite, 103 Gigantolite, 102 Qillingite, 181 Gismondite, 102 Glance cobalt (200) Glaserite, 101 Glauberite, 106(122) Glaucodot, 197 (300) Glauconite, 181 Glaucopbane, 107 Glaucopyrite, 178 Glockerite, 179 (189) Gmelinite, 120 Gold, 275 Gold amalgam, 375 (278) Goalarite, 209 (313) GOthite, 179 (189) Gramenite, 181 Graramatite, 133 Graphic tellurium, 376 Graphite, 311 (312) Gray antimony, 284 Gray antimony, niccoliferous (207) Gray copper, 247 Green vitriol (189) Greenockite, 316 Greenovite, 120 Groroilite, 171 (175) Grossularite, 119 INDEX OE MINERALS. 449 Griinauite, 203 OrUnerde, 181 Grunerite, 181 Guadalcazarite, 360 (363) Guanajuatite, 236 (340) Guarinite, 130 (129) Gummite, 343 (244) Gymnite, 132 Gypsum, 117 (131) Haa/rsale, 139 Haematostibiite, 172 Haidingerite, 118 (135) Halite, 105 llalloysite, 140 Halotricbite, 139, 179 (190) Hamartite, 105 Harmotome, 113 (115) Hartite, 311 Hatchettite, 311 Hauerite, 171 (175) Hausmannite, 171 (115) (175) Hailynite, 107 Hayesine, 118 Heavy spar, 113 Hedenbergite, 119 Hedypbane, 319 (339) Heliotrope, 317 Helvite, 146 (148) Hemafibrite, 172 Hematite, 179 (189) Hepatic cinnabar, 360 (363) Hercynite, 179(189) Herscbelite, 130 Hessite, 364 (268) Heteromorpbite, 318 Heterosite, 173 (177) Heulandite, 130 Hielmite, 383 Hisingerite, 181 Hoernesite, 131 (136) Homicblin, 246 (254) Horbacbite, 203 (20?) Hornblende, 133 Horn quicksilver, 260 Horn silver, 265 Hornstone, 317 Hortonolite,«133 Howlite, 130 (129) Huantajayite, 365 Huascolite, 309 Hnebnerite, 172 (177) Humboldtilite, 119 Humboldtine, 180 (191) Humite, 133 (137) Hureaulite, 172 (177) Hyacintb, 160 (162) Hyalite, 317 Hyalopbane, 102 Hyalosiderite, 133 Hydrargillite, 138 I-Iydroboracite, 118 (124) Hydroborocalcite, 118 Hydromagnesite, 131 (135) Hydrophane, 317 Hydrozincite, 310 (214) -Hyperstbene, 133 Hypocblorite, 237 (343) Hypoxantbite, 181 Iberite, 102 Idrialite, 311 Idocrase, 119 Iglesiasite, 210 (214) llmenite, 181 Ilmeuorutile, 279 Indigo copper, 246 lodyrite, 266 lolite, 133 Iridium, 273 Iridosmine, 273 (274) Irite, 273 Iron, native, 178 (187) meteoric, 178 (187) titanic, 181 (193) Iron ore, bog, 179 (189) " brown, 179 magnetic, 178 pisolitic, 179 red, 179 spatbic, 180(191) specular, 179 (189) Iserite, 181 Isoclasite, 118 Ittnerite, 107 Jacobsite, 179 (189) Jadeite, 107 Jalpaite, 365 (270) Jamesonite, 318 (334) Jarosite, 101, 106 (189) Jasper, 317 Jasp-opal, 317 Jeffersonite, 119 Jobannite, 343 Jobnstonite, 217 (224) Jordanite, 218 (335) Joseite, 336 (340) Juliauite, 343 (353) Kainite, 101 Kalieisenglimmer , 102 Kalinite, 101 (142) Kaliopbilite, 101 Kammererite, 133 (300) Kaneite, 171 (175) Kaolin, 140 Kaolinite, 140 Karelinite, 337 (341) Keilbauite, 130 (130) Kermesite, 384 (390) Kerstenite, 319 (229) 450 INDEX OF MINERALS. Kibdelopliane, 181 Kieserite, 131 (134) Kilbrickenite, 317 (224) KiUinite, 102 Klaprotholite, 236 (241) Klipsteinite, 173 Knebelite, 172 Koialtursenkies, 178 Kobaltbeschlag, 198 Kobellite, 218 (226) Koenlite, 311 (312) Kongsbergite, 260 Kmtigite, 210 Krantzite, 311 Kraurite, 180 Kreittonite, 210 (315) Krennerite, 276 (278) Kupferblende, 246 (353) Kupferpecherz, 248 (256) Kupfemchiefer. 295 Kupferschwflrze, 'HI (156) Kyrosite, 178 (188) Labradorite, 107 Lagonite, 180 Larapadite, 171 (176) Lanarkite, 319 (238) Lancasterite, 131 (13 ) Langite, 247 (356) Lanthanite, 165 (168) Lapis lazuli, 107 Larderellite, 112(316) Laumontite, 120 Laurionite, 318 Laurite, 273 (275) Lautite, 247 (255) Lavendulan, 198(303) Laxmannite, 319 Lazalite, 131 (134) Lead, earthy carbonate, 219 (239) native, 217 (233) Leadbillite, 219(228) Lebrbacliite, 217 (334) Lepidocrocite, 179 Lepidolite, 103 Lepidomelane, 103 Lettsomite, 247 Leucite, 10^ Leucoplianlte, 107 (148) Leucopyrite, 178 (187) Libetbenite, 348 (357) Liebenerite, 102 Liebigite, 343 (345) Lignite, 311 Lime uranite. 243 Limonite, 179 (189) Linarite, 218 (328) Linnaeite, 197 (301) ■ Liroconite, 348 (358) Litbia mica, 103 Litbiopborite, 171 (176) Loncbidite, 178 (188) Lorandite, 301 (304) Loxoclase, 102 Ludwigite, 180 (191) Luneburgite, 131 Luzonite, 346 (354) Magnesia mica, 102 Magnesia-iron mica, 103 Magnesioferrite, 179 (189) Magnesite, 131 (135) Magnetic pyrites, 178 Magnetite, 178 (189) Malachite, 248 (257) Malacolite, 119 Malacon, 160 (162) Maldonite, 276 Manganblende, 171 Manganese, black silicate 173 Manganepidot, 120 Manganite, 171 (175) Mangankieael, 172 Manganocalcite, 172 (177) Marcasite, 178(188) Margarite, 120 Marmatite, 309 Mascagnite, 113 Massicot, 218 (227) Matildite, 237 (341) Matlockite, 218 (227) Meerschaum, 133 Megabromite, 265 Meionite, 119 Melaconite, 347 (356) Melanite, 119 Melanocbroite, 239 Melanterite, 179 (189) Melilite, 119 Meliphanite, 107 Mellite, 139 (144) Meionite, 303 Menaccanite, 181 (193) Mendipite, 318 (237) Mendozite, 106 (143) Menegbinite, 217 (234) Menilite, 317 Mercury, 260 (263) Mesitite, 181 . Mesolite, 107 Mesotype, 107 Metabrushite, 118 Metachlorite, 181 Miargyrite, 265 (270) Mica, 102 Microbromitp, 265 Microcline, 103 Miesite, 819 Millerite, 203 (207) Milky quartz. 317 Mimetite, 819 (228) Mineral oil, 311 INDEX OF MINERAL8. 451 Minium, 218 (227) Mirabilite, 106 Mispickel, 178 (187) Misy, 179 Mizzonite, 107 Moclia stone, 317 Molybdenite, 293 (294) Monazlte, 165 (167) Jlonimolite, 220 Monradite, 132 Montanite, 287 (341) Monticellite, 119 Morenosite, 203 (208) Moresnetite, 210 Morion, 817 Mosandrite, 165 (170) Muromontite, 150 (157) Muscovite, 102 Myelin, 140 Nadorite, 218 (227) Nakril. 140 JSTagyagite, 276 (279) Nantokite, 247 (356) Napbtlia, 311 H^atrolite, 107 Natron, 106 Naumannite, 264 (268) Needle-ironstone, 179 Neft-gil, 311 Nemalite 131 (133) Neotocitp, 172 Nepbelite, 106 Nephrite, 132 Niccolite, S02 (206) Nickel, arsenate, 203 (308) glance (207) gymnite, 304 ochre, 303 vitriol, 203 Nigrine, 279 Niobite, 181 Nitre, 101 (310) Nitroca'cite, 117 (122) (310) JJontronite, 181 Nosite, 107 Numeite, 204 Nussierite, 219 ■Ocbre, 179 (189) Ocbrolite, 230 Octabedrite, 279 (281) (EJlacberite, 102 (Erstedite, 160 (161) ■Okenite, 120 Oligoclase, 106 Olivenite, 248 (258) Olivine, 131 Ompbacite, 119 Oncosine, 102 Onofrite, 260 (263) Onyx, 317 Opal, 317 (318) Orangite, 163 Orpiment, 301 (304) Ortbite, 165 (168) Ortboclase, 103 Osmiridiuni, 273 Osteolite, 118 Ouvarovite, 119 (300) Owenite, 181 Oxalite, 180 Ozocerite, 311 (312) Pacbnolite, 106 (141) Paisbergite, 172 Palladium, 373 (274) Palladium gold, 275 (378) Pandermite, 118 Paraffin, 311 Paragonite, 107 Parisite, 165 (167) Partzite, 220 Paalite, 133 Pearl spar, 118 Pectolite, 107 Peganite, 139 (143) Penninite, 133 Pentlandite, 203 (308) Percylite, 218 (327) Periclasite, 130 (133) Pericline, 106 Peridote, 131 Perofskite, 119 (127) Petal ite, 109 Petroleum, 311 Petzite, 275 (278) Pharmacolite, 118 (135) Pharmacosiderite, 180 (192) Pbenacite, 146 (147) Phillipsite, 103 Pblogopite, 103 Phoenicocbroite, 219 (239) Pbolerite, 140 Pbosgf nite, 318 (237) Pbospbocbromite, 219 Pbospburanylite, 343 \ Pickerlngite, 131 (134) Picotite, 179 Picrolite, 183 Picropbarmacolite, 118 (135) Picrosmine, 133 Piedmontite, 120 Pimelite, 204 Pinguite, 181 Finite, 103 Pisanite, 179 (190) Pissopbanite, 180 (190) Pistacite, 119 Pistomesite, 131 453 INDEX OF MINERALS. Pitchblende, 243 Pitticite, 180 (192) Plagionite, 21« (224) Planerite, 139 Plasma, 317 Platinum, 272 (273) Platiniridium, 273 Plattnerite, 218 (227) Pleonaste, 133 (138) Plumbic ochre, (227) Plumbocalcite, 118 (124) Plumboferrite, 179 Plumbogummite, 219 (229) Plumbostib, 217 Phimosite, 218 Polianite, 171 (175) Pollucite, 105 Polybasite, 265 (269) Polycrase, 150 (154) Polydymite, 203 (207) Poly halite, 101 (122) Polysphaerite, 219 Porpezite, 275 Potash mica, 102 Prase, 317 Prehnite, 120 Prochlorite,.132 Proustite, 265 (269) Pseudomalacbite, 247 (257) Pseudotriphite, 180 (190) Psilomelane, 171 (115) (175) Pucherite, 237 (242) Purple copper, 246 Pycnite, 139 (145) Pyrargyrite, 265 (270) Pyrite, pyrites, 178 (188) Pyrites, radiated, 178 spear, 178 Pyrochlore, 119 (126) Pyrochroite, 171 (176) Pyrolusite, 171 (175) Pvromorphite, 219 (228) Pyrope, 132 Pyrophanite, 172 Pyrophyllite, 140 Pyrophysalite, 139 (145) Pyroretin, 311 Pyrorthite, 165 (169) Pyrosclerite, 183 Pyrosmalite, 182 (194) Pyrostilpnite, 265 (3T0) Pyroxene, 119 Pyrrhosiderite, 179 Pyrrhotite, 178 (188) Quartz, 317 (318) Quellerz 179 Rabdionite, 171 (176) Raimondite, 179 Rammelsbergite,-203 (207) Baseneisensiein, 179 Realgar, 301 (304) Red antimony, 284 Red copper, 247 Red silver ore, 265 Retinite, 311 (313) Rhagite, 237 (241) Rhodium gold, 275 (378) Rhodizite, 118 Rhodochrome, 132 Rhodochrosite, 172 (177) Rhodonite, 172 Riebeckite, 107 Ripidolite, 132 Rittingerite, 264 Rock crystal, 317 Roemerite, 179 (190) Roesslerite, 131 (136) Romeite, 118 (126) Rose quartz, 317 Roselite, 118(125) ROttisite, 203 Ruby, 138 Ruby silver, 265 Rutile, 279 (281) Safflorite, 197 (200) Sal ammoniac, 112 Salite, 119 Samarskite, 149 (153) Sanidine, 102 Saponite, 132 Sapphire, 138 Sapphire quartz, 317 Sardonyx, 317 Sartorite, 217 (225) Sassolite, 315 (316) Saussurite, 107 Scapolite, 119 Scbeelite, 118 (125) Scheererite, 311 (313) Schefferite, 119 Schirmerite, 237 Schorlomite, 120 (130) Schwartzembergite, 218 Scolecite, 120 Scolopsite, 107 Scorodite, 180 (192) Selenguecksilberkupferblei, 217 (224) Selenbleikupfer, 217 (334) SelenkupferUei, 217 (223) Selenschwefelquecksilber, 263 Sellaite, 131 Semiopal, 317 Senarmontite, 284 (290) Sepiolite, 133 Sericite, 102 Serpentine, 133 Siderite, 180 (191) Silicoborociilcire, 120 Sillimanite, 139 INDEX OF MINERALS. 453; Silver, 264 (268) Silver glance, 364 Skier oMas, 317 Skutterudite, 197 (300) Smaltite, 197 (200) Smithsonite, 210 (313) Smoky quartz, 317 Soapstone, 133 Soda mica, 107 Soda nitre, 106 (310) Sodalite, 107 Sordavalite, 181 Spadaite, 133 Spathiopyrite, 197 Specular iron, 179 Sperrylite, 373 Spliaerocobaltite, 197 (303) Sphalerite, 209 (212) Sphene, 120 Spinel, 133 (138) Spodumene, 109 ^reustein, 107 StafEelite, 118 Stanmt, 233 (235) Stannite, 233 (235) Stassfurtite, 131 (136) Staurollte, 140 Steatite, 133 Steinmanuite, 217 Sleinmark, 140 Stephanite, 264 (269) Sternbergite, 265 (370) Stibiconite, 284 (390) Stibnite, 384 (389) Stilbite, 120 Stilpnomelane, 181 Stilpnosiderite, 179 Stirlingite, 181 Stolzite, 320 (331) Stratopeite, 173 Strengite, 180 Stromeyerite, 365 (370) Strontianite, 116 Stylotypite, 347 (355) Succinite, 311 Sulphur, 319 (330) Sumpferz, 179 Sundtite, 265 Sussexite, 173 (177) Svanbergite, 106 Syepoorite, 197 (201) Sylvanlte, 276 (378) Svlvite, 101 Symplesite, 180 (193) Syngenite, 101 Szaibelyite, 131 Tachydrite, 117(133) •J'agilite, 248 (257) Talc 133 Tantalite, 181 (193) Tapiolite, 194 Tarnovicite, 118 (124) Tasmanite, 311 Tecoretin, 311 Telluric bismuth, 236 Tellurite, 307 Tellurium, 307 Tennantite, 246 (253) Tenorite, 247 Tephroite, 172 Tetradymite, 236 (240) Tetrahedrite, 247 (354) Tetraphylin, 109 Tbarandite, 118 Thenardite, 106 Thermonatrite, 106 Thomsonite, 120 Thorite, 163 Thraulite, 181 Thrombolite, 248 (257) Thuringite, 181 Tiemannite, 260 (263) Tilkerodite, 197, 217 (201) (223) Tin, 333 Tin pyrites, 233 Tin stone, 233 Tinkal, 106 Titanite, 120 (139) Tocornalite, 266 Topaz, 139 (145) Torbernite, 243 (345) Tourmaline, 140 Tremolite, 132 Trichalcite, 248 (258) Tridymite, 317 Trinkerite, 311 Triphylite, 109 (177) Triplite, 172 (177) Tritochorite, 219 TrOgerite, 248 (245) Troilite, 178 Trona, 106 Troostite, 210 TschefEkinlte, 165 (170) Tschermigite, 112 (142) Tungstite, 390 (■<;91) Turgite, 179 (189) Turquois, 139 (143) Tyrolite, 248 (358) Ulexite, 100 (134) Ullraannite, 203 (207) Umangite, 246 (253) Umira, 140, 181 Unghvarite, 181 Uraconite, 243 Uraninite, 243 (244) Uranochalcite, 243 Uranocircite, 243 Uran-Jcalkcarbonai, 243 (345> Uranophane, 343 (245) 454 INDEX OF MIUEEALS. Uranospiuite, 243 Uranotliallite, 243 Uranotil, 243 Uranvitriol, 243 (244) Urao, 106 . Valentinite, 284 (290) Vauadinite, 219 (230) A^anadite, 219 Variscite, 139 (144) Varvicite, 171 (175) Vauquelinite, 219 (230) Vermiculite, 133 Vesuvianite, 119 Vivianite, 180 (190) Voglite, 243 (245) Volborthite, 248 (259) Voltzite, 209 (213) Wad, 171 (175) Wagnerite, 131 (134) Walcbowite, 311 Walpurgite, 237(241) Wapplerite, 118 (125) Water, 309 Wavellite, 139 (143) WeisMeierz, erdiges, 219 WeiasgUtigen, 265,(271) Weisstellur, 276 (378) Wernerite, 119 Whevvellite, 118(124) Wbitneylte, 24B (252) Willemite, 210 (315) Williamsite, 133 Wilaite, 119 Witmui/ispaih, 237 Witherite, 112 (114) Wittichenite, 236 (241) Wittingite, 173 W5ljlerite, 160 WolcUonskoite, 297 (300) WolfacUite, 203 Wolframite, 181 (193) WoUastonite, 119 (127) Woodwardite, 247 Wulfenite, 219 (231) Wurtzite, 209 XantUarsenite, 173 Xanthoconite, 265 (270) XantUopliyllite, 133 Xantbosiderite, 179 (189) Xenotime, 149 (153) Xylotile, 181 Yellow ocbre, 179 Yttrocerite, 149 (150) Yttrotantalite, 149 (153) Yttrotitanite, 120 Zaratite, 203 (208) Zeagonite, 103 Zeunerite, 243 Zinc blende, 209 bloom, 210 vitriol, 209 Zincite, 309 (313) Zincosite, 310 ZinkUeispath, 310 Zinkenite, 318 (324) Zinnwaldite, 103 Zippeite, 243 Zircon, 160 (162) Zorgite, 317 (228) Zundererz, 218 (225) Zwieselite, 172 (177) INDEX OF METALLURGICAL PEODUCTS. Abstricb. 220, 233, 367, 406 Abzug. 232 Amalgam, copper, 260 gold, 360 lead, 260 silver, 266, 873 Amalgamation residues, 260 Arsenic, metallic, 301 ■white, 301 Bears from copper smelting, 249 iron " 183, 373 Bell metal, 372, 397, 423 Bleiofenbrucli, 183 Brass, 369, 396 Bronze, 397, 433 Cadmia from iron furnaces, 183, 311 lead " 330 Copper, black, 195, 330, 332, 349, 369 cement, 349 raw, 349, 369 refined, 249, 869 Cupel bottoms, 406 Eisensauen, 183 Enamel, 430 Flue dust, 351 Forge scales, 183 Oiclitenfehwamm, 211 Gun metal, 372, 397, 423 Iron, raw, 182, 195 Lead, raw, 230, 331, 343, 392 silver, 266 Lead fumes, 230 smoke, 320, 232 Liquation discs, 392 residues, 395 Litharge, 220, 382, 367, 406 Matt, copper, 183, 385 lea,d, 183, 375, 385, 399 Packfong, 343, 441 Regulus, 385 EofiofenJyrucJi, 182 Bohachlacken, 403 Bohstein, 183, 311, 385 ScafEolding, 183 Silver, brightened, 366, 368 cement, 266, 368 German, 343, 369, 441 jeweller's, 368 refined, 266, 368 retort, 266, 368 Slags, copper, 391 lead, 230, 333, 403 raw, 403 tin. 431 Smalt, 437 Speculum metal, 397 Speisses, 195 Speiss, cobalt, 408, 438 lead, 220 nickel, 408, 438 Steel, raw, 182, 195 Steinschlacken, 421 Test mass. 266 Tin, 283, 335 Tin deposits, 233 'scraps. 233 Tutenag. 441 Tutty, 183, 385 Vitriol, blue, 391 Zinc dust, 216 raw, 210 Zinnasche, 420 455 GENERAL INDEX. EXPI.ANATION.— r denotes that the substance, in the place referred to, is a reagent. PAGE Acetic acid, r 53 Alcohol, T 56 Alamina, examination for 140 Ammonia, carbonate of , r 54 examination for 113 molybdate of, r 55 Ammonia, r • 53 Ammonium, chloride of, r 55 sulphide of, r 55 Antimony, examination for 385 flame- test for 77 test for, in open tube 64 " on coal 67 Arsenic, examination for 301 flame-test for 77 test for, in open tube 64 " on coal 67 Arsenic, r ' ^ Balance, blowpipe 26 Biryta, examination for 113 flame-test for 76 Berylla (glucina) 146 Bismuth, examination for 238 test for, on coal 68 Blast I*' Blowpipe, * gas 10 Blowpipe lamp, Berzelius' • 8 Bone-ash, r *'^ Boracic acid, examination for 316 flame-test for 75 4S Boracic aoiQ, r 457 458 GENERAL aNDEX. PAGE Borax, r 46 beads, color of ~83 Brazil-wood paper, r 51 Bromine, examination for 337 Bunsen's gas-lamp 9 Buttons, various apparatus for measuring gold and silver, 27 Cadmium, examination for 216 test for, on coal 68 Carbon and Carbonic acid 311 examination for 313 Cerium, examination for 166 Charcoal, art'ficial 15 *' capsules 16 " crucibles 16 " parallelopipedons 19 " square prisms , 18 "Charcoal, natural 15 Chlorine, examination for 336 Chromium, examination for 297 Clay capsules 33 crucibles 33 " lining for 26 cylinders for holding charcoal crucibles , 17 prisms 19 Closed tubes 33 Coal-holder for square coals 40 Coatings on charcoal... 67 'Cobalt, examination for 198 nitrate of , r 48 Cobalt, quantitative assay of 434 Cobalt solution 48 examination with 91 Coloration of flame 73 Columbium (niobium) 283 Copper, examination for 349 flame-test for 75, 77 oxide of, r 53 quantitative assay of 385 " " in alloys 392 sulphate of, r 56 Cupel-holders 39 Cupellation loss, table for 364 Cupels 39 'Cyanogen, occurrence of 330 Didymium, examination for 166 Distilled water, r 54 GENERAL INDEX. 459, PAQE Erbia, examination for 150- Flame, blue j5 oxidizing , 13 reducing ^_ _ ^ j4 Flame-tests i^^ Flaming 80 Fluor spar, r 51 Fluorine, examination for 339. Fuel 8 Fusibility, figures denoting 100 scale of 71 testing for 7O' Fusions with soda and borax 94 nitre or bisulpliate of potassa 97 Glass tubes, dosed , 32 open 21 Glucina, examination for , 146 Gold, examination for 276 quantitative assay of 374 Gold, r 50 Gold buttons, measurement of 29 Graphite, r 53 Gypsum, r 63 Hydrochloric acid, r 53 Indium, test for, on coal 68 Iodine, examination for 328 Iridium, minerals containing 272 Iron, examination for 183 sulphate of, r 55 Iron, T So Lamp i • 8 wick 8 Lanthanum, examination for 166- Lead, acetate of, r 56 examination for 220 flame-test for 77 pure, r 49 quantitative assay of 399 test for, on coal 67 Lime, examination for 121 flame- test for , 75 Lithia, examination for 109 fliime-test for ; 74 Litmus paper, r 50. 460 GENEBAL IKDEX. PAGE Magnesia, examination for lSi3 Magnesium, i 52 Manganese, examination for 173 Matrasses 32 Mercury, examination for 361 quantitative assay of 443 test for, in open tabe 65 Molybdenum, examination for £94 test for, on coal 69 Molybdic acid, flame-test for , , 76 Nickel, examination for 304 C quantitative assay of 434 Niobium, examination for 383 Nitre, X '. 48 Nitric acid, r 53 Nitric acid, examination for 310 Open tubes 31 Osmium 372 Oxalic acid, r 53 Oxidizing flame 13 purity of 13 strengtli of 14 Palladium, examination for 273 Phospliorus and pbosphoric acid 324 flame-test for 76 salt of, r 47 ' ' beads, colors of , 84 Platinum, chloride of, i 54 examination for 273 Platinum disU 31 foil 21 spoons 20 wires and holder 19 Plaster of Paris tablets 66 Plattner's flux 404 scale 28 Potassa, antimonate of, r 51 bisulpUate of , r 48 carbonate of, r 54 caustic, r 53 examination for 103 flame-test for , 74 neutral sulphate of, r 54 nitrate of , r 48 oxalate of , T 46 GENERAL INDEX. 461 FAQi; Potassium, cyanide of, r 46 ferrocyanide of, r 55 iodide of, witli sulphur, r 53 Quartz, r 51 Beducing flame ]4 purity of , 14 strengtli of ., 15 Reduction of oxides witli oxalate of potassa and cyanide of potassium 90 " soda 89 Eliodium 273 Roasting , . . . . 78 Salt, r 51 Selenium, examination for 333 flanse-test for 77 test for, in open tube 64 " on coal 67 Silica, T 51 Silicic acid, examination for 318 minerals containing 317 Silver, examination for , 366 quantitative assay of 350 " " in alloys 368 test for, on coal 69 Silver, r 50 cbloride, r 53 Soda, examination for < 108 Soda, r 43 Soda carbonate, examination with 88 Soda paper 25 cylinders 43 Spirit lamp ' 10 Starch, r 53 StTontia, examination for 116 flame- test for 75 Sulphur and sulphuric acid 319 examination for 330 test for, in open tube 63 Sulphuric acid, 1' 53 Supports, direct 15 indirect ^ 35 Tantalum, examination for r 283 Tartaric acid, r 54 Tellurium, examination for 807 test for, in open tube 65 " on coal 67 462 GElfEEAL INDEX. , ^ , FAOB Tellurous acid, flame-test for 76 Test lead, r 49 measure for 42 Test papers, r 50 Thallium, flame-test for 73 test for, on coal 67 Thoria, examination for, 16Si Tin, examination for 233 quantitative assay of 414 " " inalloys 423 test for, on coal 68 Tin, r 49 Titanium, examination for 280 Touchstone, r 53 Tungsten, examination for 291 Uranium, examination for 243 Vanadium, examination for 296 Water, examination for 809 Weights 27 Yttria, examination for 150- Zinc, behavior of Ill examination for 211 test for, on coal 68 Zirconia, examination for 160- TABLE OF ATOMIC WEIGHTS.* Name. Aluminium Al Antimony Sb Argonf A Arsenic As Bariam Bel Bismuth Bi Boron B Bromine Br Cadmium Cd Csesium Cs Calcium Ca Carbon , C Cerium Ce Chlorine CI Chromium Cr Cobalt Co Copper Cu Didymium :( Di Erbium Er Fluorine F Gallium Ga Germanium , Ge Glucinum ) Gl ) Beryllium ) Be { Gold Au Helium f He Hydrogen H Symbol. Atomic Weight. Indium. Iodine Iridium. . . , Iron Lanthanum. Lead Lithium. . . . Magnesium . Manganese. . Mercury . . . . In I Ir Fe La Pb Li Mg Mn Hg 27.0 130.0 40.0 75.0 137.0 208.0 11.0 80.0 113.0 133.0 40.0 13.0 141.0 35.4 52.0 59.0 68.3 146.0 166.0 19.0 69.0 72.0 9.1 197.0 4.0 1.0 113.4 127,0 193.0 56.0 139.0 207.0 7.0 24.0 54.0 200.0 Name. Molybdenum . Nickel Niobium ) Columbium j ' Nitrogen Osmium Oxygen Palladium , . . Phosphorus. . Platinum . . . . Potassium . . . , Rhodium . . . . Rubidium, . . , Ruthenium.. . Samarium. . . , Scandium. . . . Selenium . . . . Silicon Silver Sodium Strontium. . . . Sulphur Tantalum . . . . Tellurium , . . , Terbium Thallium Thorium Thulium Tin [Titanium Tungsten , Uranium Vanadium Ytterbium rttrium Symbol. Zinc Zirconium ,1 Zr Mo Ni Nb Cb N Os O Pd P Pt K Rh Rb Ru Sm Sc Se Si Ag Na Sr S Ta Te Tb Tl Th Tu Sn Ti W U V Yb Y Zn Atomic Weight. 95.6 58.0 94.0 14.0 191.0 16.0 106.0 31.0 195.0 39.0 104.0 85.5 104.0 150.0 44.0 79.0 28.0 108 23,0 87.6 33.0 183.0 136.0 135.0 304.0 234.0 171 118.0 48.0 184.0 339.0 51.4 173.0 90.0 65.0 90.0 * Fownes' (Watts') Chemistry, 14th edition. •f Chemiker Kalender, 1900. t Replaced by Neodymium (144) and Praseodymium (140). Chemiker Kalen- der, 1900. 463 Works on Chemistry and Physics PUBLISHED BY THE D. VAN NOSTRAND CO. ARNOLD, Dr. R. Ammonia and Ammonium Compounds. A Practical Manual for Manufacturers, Chemists, Gas Bngineers, and Dry- salters. Second Edition. i2mo, cloth . $2.00 BERNTHSEN, A. A Text-Book of Organic Chemistry. Trans- lated by George M'Gowan, Ph.D. Fourth English Edition. Revised and extended by author and translator. 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