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Maps, plates, charts, etc., may be filmed at different reduction ratios. Those too large to be entirely included in one exposure are filmed beginning in the upper left hand corner, left to right and top to bottom, as many frames as required. The following diagrams illustrate the method: Les cartes, planches, tableaux, etc., peuvent dtre film6s 6 des taux de reduction diffdrents. Lorsque le or oument est trop grand pour dtre reproduit en un seul cliche, il es. filmd 6 partir de Tangle supdrieur gauche, de gauche d droite, et de haut en bas, en prenant le nombre d'images ndcessaire. Les diagrammes suivants illustrent la mdthode. 1 2 3 t 2 3 4 5 6 . ■/ •' I CHAPMAN'S BLOWPIPE PRACTICE AND MINERAL TABLES. 117 h, U WrORKS — SY — Professor E. J. CHAPMAN, Ph.D. LL.D. I. ^ MINERALS AND GEOLOGY OF CENTRAL CANADA, COMPRISING THE PROVINCES OF ONTARIO AND QUEBKO. Third Edition. With S50 wood-cuts and a copious Index. II. AN OUTLINE OF THE GEOLOGY OF CANADA. INCLUDING ALL THE PROVINCES OP THE DOMINION. With six sketch-mapa arid six plates of characteristic fossils. A New Edition in Press. IIL BLOWPIPE PRACTICE. WITH ORIGINAL TABLES FOR THE DETERMINATION OF MINERALS. This work has been favorably noticed in the 11th and 12th editions of Vcn Kobell's celebrated Ta/eln zur Bestimmung der Mineralien. Second Edition. IV. PRACTICAL INSTRUCTIONS FOR THE DETERMINATION BY FURNACE ASSAY OF GOLD AND SILVER IN ROCKS AND ORES. Second Edition. V. THE MINERAL INDICATOR. A PRACTICAL OUID2 TO THE DETERMINATION OF GENERALLY- OCCURRING MINERALS. Second Edition. THE COPP, CLARK, CO. (Limited) : TORONTO. BLOWPIPE PRACTICE: AN OUTLINE OV BLOWPIPE MANIPULATION AND ANALYSIS, I 'I I WITH ORIGINAL TABLES FOR THE DETERMINATION OF MINEEAI.S. BY E. J. CHAPMAN, Ph.D., LL.D. PROFESSOR OF MINERALOGY AND GEOLOGY IN THE UNIVERSITY OF TORONTO. Second Edition : Revised and Enlarged. tToronto : The Copp, Clark, Co., (Limited) : 9 Front Street West. 1893. Entered according to Act of the Parliament of Canada, ^i^^ear one thousand eight hundred and ninety-three, by The Copp, Clark Company, Limited Toronto, Ontario, in the Office of the Minister of Agriculture. fi PREFACE. TO THE FIRST EDITION. If .1 -5' The title page of this little woik iiuliciites suociiiotly tlio scope and character of the book. The work comprises two distinct parts : au introductory sketch of the use of the Blowpipe in qualitative mineral examinations ; and a series of Tables, with chemical and crystallo- graphic notes, for the practical determination of minerals, generally. In the first portion of the work, the '■, nter's aim has been t(j syste- matise and condense as far as possible : but, although confessedly a mere outline of the subject, this introductoiy portion will not be found altogether devoid of original matter. The seventh section contains a new and greatly simplified |tlan of J3lowpipk Analysis, by which the general comj)osition of an unknown substance may be determined in most cases very rapidly and with comparatively little trouble. As a rule, the methods of Blowpipe Analysis, h'tlierto published, are little more than Tables of Reactions. They attempt no separation of electro-negative bodies from bases, but mix u > the two, very illogically ; and they exact the performance of many unnecessary experiments, by which certain components become detected over and over again, whilst others escape detection tlto- ^ether, or are recognized only after much unnecessary delay. These defects are remedied very materially, it is thought, in the mechod now proposed. The Determinative Tables, which occu})y tlie second and principal portion of the work, are also original. In their arrangement, an attempt is made to place botlies of related composi- tion, only, under the same subdivision : so as to avoid, wherever pos- sible, the unnatural collocations so commonly seen in Tables of this character. It will be evident, however, that without greatly vi ULOWl'II'E PRACTICE. increasing the number of the Tables, com{)lete success in this respect is not always attainable. The Tables inchule, jiractically, a" the better known or well characterised nnneral hpecies ; but as many of these are rar(!ly met with, or are comi)aratively of little importance, an Explanatory Note, i-eferring only to species of ordinary occur- rence, is attaciied to each Table. In these Notes nuich additional infor- mation is given respecting the crystallization, spectroscopic reactions, and other distinctive characters of leading species. The spectrosco[)e recommended for use, in these investigations, is a simple, direct-vision pof^ket-spoctroscope, such as can be carried very conveniently, with acconn)anying Bunsen-burner (the foot unscrewed), in a spare corner of the blowpipe case. Toronto : Aui/ust 12th, ISSO. *j^*In this new edition, the original plan of the work has been ])ractically retained, but the subject-matter has been thoroughly revised, and numerous additions have been made to it, without, however, materially increasing the size of the book, or affecting its synoptical character. — E. J. C. University of Toronto : July 1, 1893. CONTENTS. M §2. §3 §4 §5, §'6. PART I. —Brief Sketch of the History of the Blowpipe 2 —The Blowpipe : Its Structure and General Use 4 — Accessory Appliances and Reagents 7 —Structural Parts and Chemicai, Pkoperties of Fl/me 8 — Blowpipe Operations : I. Tho Fusion Trial jo II. Treatment in closeil Tube : (i) 'I'reatment in Flask or Bull)-Tul)e 13 (ii) Treatment in Closed Tube, proper 14 III. Boasting ; and Treatment in Open Tube : (i) Roasting on Charcoal, Porcelain, and other supports 15 (ii) Roasting and Sublimation in Ojjen Tubes 15 IV. Treatment v/ith Nitrate of Cobalt iq V. Formation of Glasses on Platinum Wire, or on Charcoal : (i) Details of Process ; Flaming, Ac if, (ii) Table of Borax (Classes n^ (iii) Phosphor-Salt Glasses 19 (iv) Glasses formed with Sodium Carbonate 19 VI. Reduction on VII. Cupellation .... ^^ VIII. Fusion with Reagents in Platinum Spoon 04 —Blowpipe Reactions : (i) Non-metallic Bodies „p 2b 1, Oxygen ; 2, Hydrogen ; .3, Sulphur ; 4, Selenium ; 5, Ni- trogen ; 6, Chlorine ; 7, Bromine ; 8, Iodine ; 9, Fluorine ; 10, Phosphorus ; 11, Boron ; 12, Carbon ; 13, Silicon, (ii) Unoxidizahk Metals 05 14, Platinum ; 15, Gold ; U, Silver, (iii) Volatilizahle Metals „- 17, Tellurium; 18, Antimony; 19, Arsenic ';" 20, Osmium'; 21, Mercury ; 22, Bismuth ; 23, Lead ; 24, Thallium ; 25, Cadmium ; 26, Zinc ; 27, Tin (?) vii Viil (X)NTKNT.S. (iv) Flii.i-i'iildiirin;/ Mifiiln 4.') as, ('(ipper; 'Jit, Nickel; 'M, Colmlt j 31, Iron; 32, Tung- Htoiiiiin ; 33, Mi)lylMU'iiiiiii ; 3i, Mari^'iinoHo ; 'J"), ('iii'oiniuin ; 37, I'liiiiuiiii ; 3S, Ci-riuiM ; 31), 'riUniuiii. (v) Achrok Mttnl.i 50 40, 'rnntiilutn (?) ; 41, Aliimiiuun ; 4'i, (iluuiniiiii ; 43, Zir- coniuiii ; U, Yttrium ; 4.'), MivgiiuHiuin. (vi) Fliuiii'-rohinriiiij Mititln 59 4(5, Ciiloiuin ; 47, Stroiitiiiin ; 4S, Hariiun ; 4!), Litiiium ; 50, Soiliuni ; 51, I'l.tiiHuiuiii ; 5'J, Aiiunouiuin. §7.— Plan of Analyst?' (i) D'jtenniiiiitiou of the Clicniical CJroup to which a mineral aub- Htiince liulongM G4 (ii) Detorniinatiou of the Base or BaHea 67 ApI'ENDIX;— OHIOINAI, ('oNTRUil'TIONS T(» Bt.OWl'II'R ANALYSIS. 1. Reaction of Manganese Salts on Baryta 75 2. Detection of Baryta in the presence of Strontia . 75 3. Detection of Alkalies in the presence of Magnesia 76 4. Method of Distingiiisliing the red liame of Lithium from that of Strontium 76 5. Metiiod of Distinguishing FeO from Fe^O' in Silicates and other conipoinids 77 G. Detection of Lead in presence of Bismuth 78 7. Detection of Lithia in i)re8ence of Soda 79 8. Action of Baryta on Titanic Acid 79 9. Detection of Manganese when present in minute quantity in min- eral Bodies 80 10. The Coal Assay 80 11. Phosphorus in Iron Wire . . 85 12. Detection of minute traces of Copper in Iron Pyrites and other bodies 86 13. Detection of Antimony in tube sublimates 87 14. Blowpipe reactions of Thallium 88 15. Opiilesceuce of Silicates in Bhosphor-salt 90 16. Reactions of Chromium and Manganese with Sodium Carbonate. 91 17. Detecti(m of Cadmium in presence of Zinc in blowpipe experi- ments 92 18. Solubility of BiHmuth Oxide in Sodium Carl mate before the blowpipe 92 19. Detection of Carbonates in Blowpipe Practice 93 20. Detection of Bromine in Blowpipe Experiments 94 21. Blowpipe reactions of Metallic Alloys 95 i:a I 45 m 69 CONTKNTS. I2 PART 11. Obkiinal Tahi.ks kok Tin; Dk.tkkmination ok Minkkai.m. Intrdductioii : Kxpliiiiatioii of CVystivl SyniliolH, c"vc 99 Aniilytical Index t<» tho '''nldfa lO.'MOt Tul.lo I., lOr. ; T. II., 107 ; T. III., 10!); T. IV., lir) ; T. V.. ll'J; T. VI., 121 ; T. VII., I-'; T. VIII., PJ.'J ; T. I.\., 128 ; T. X., 131 ; T XI., I;i8 ; T. XII., 14H ; T. XIII.. m- T. XIV., 151' ; T. XV., 150 ; T. XVI., 1(51 j T. XVII., 174 • T. XVIII., ks.J; T. XI.\., 180. T. XX., 1!»1 ; T. XXI 104; T. XXII,, 195; T. X.VIII., 100; T. XXIV., U08 • T. XXV.. 2'J7; T. XXVI., 'J41 ; T. XXVII.. 270: T. XXv'III.,'J75. Index to Part I ngo Index to Minerals described in Part II 297 Additions and Corrections o/iu AN orri.ixK or BLOWTIPK PRACTICK. AS vrniKi* r<> r>iK grAMTATlVK KXAMINATION OF MlNKHAl. Hi)niKS. 18 ■51- lUMKF SKKTiM{ OV Tin- HISTOHV OK TH K UKUVnTK. Tiu> •,»,■ of- tlu- I?la\vpi,>o. in xho .n-ts. .l.-.tos tVom :. x.mv .hstant IHMioa-:, si.npio form of xho insfrumont Imviuj; h.vn Ion- o'luplovo,!. m \\w iM-.v,-v>. ot-sol,l,Mino;. Uv j.-wollo.-s -muI othor vvorkorsin ^vol.i •uui siK.M'. Ti.is .Muploym.MU must naturally havo succosto.l its uso to tHo.il.homists; ana in tlu' ourious ooli.vtion of xvoo.louts ktuuvn as tlu> A.vVr ,>nit„.<. in ulnoli an uK-luMuist. assisto.1 hy !, iiopioto.l in (lu> p.vfo.n,aiuv of various oluMuioal op,Mi,ti. h, .so of tho Mowpipo is doarly in.iioat...l, Tiio Lihn- mutus n>rv utuvnain .lato. hu, „ lvlon,:,-s. in all prohaUilitv. ,o tl,o ho-Mnnin- o( tho sov.MU.HMUh .vntury. Vho alohonust is horo on>pKn o.l. it is ,n,o not ui tho aottial ovan.ination ot a suUst,„uv> hv l,is hlowpipo. but in tlH>oon>truotio,t or soalinj; „p of n glass vos.s.>l. Xovortl.oloss tho i>so ot il,o tnstrumont in tho ,vnvo,-sion of oalo spar into li.no is junntoa out by Krasmi s IVvKruoitv ,u his troatiso on loolan.l Spar wnttou ,n UuO ; an.l m tho A,-.. v,tr„ru. ..>•}>,, im.ui<,!is of K, nvkk. ' l^HN>shoa in ir.7i». tho bh.wpipo is mMnnnou.loa for uso tn .ho mluot.on. on oharo.vil. of n>otaM,ol.lin- Kvlios. tho roouisito olasf iHMUg pnvlm.Hl by a p,i, ..f ,i, ,i^.,,, ,,,^^ j,^ ,.,^, „,;^ o.>:..b,-u,vl alohontts, .loHAVN- Cmna Sr.u... .listn.otly ro.o.-s to ti.o ,v.l„otion of loaa :vn.i attttmony. in- tho tusion of what .uv now known .s ,ho oxi.Jos ot th.vso n,ot.,Is. on a pi.nv of oha.voal. bv luoaus of a -.soiaor itii r t': „|! 1 is BLOWPIPE PRACTICE. ing pipe " or tubulo crementorio aurifabrorum. Johann Andreas Cramer, in liis Elemenia arlis dochnastrnf, (1739) describes the use of the instrument in the examination of small pa tides of metallic bodies, and suii)e, the mouth is tilled with air, and this is forced gently but continuously down the tube by the compression of the muscles of the cheeks and lips, breathing being carried on simul- taneously by the nostrils. By a little practice, this operation becomes exceedingly easy, especially in ordinary experiments, in which the blast is rarely required to be kept up for mo.e than twenty or thirty seconds at a time. The beginner will find it advisable to restrict himself at first to the production of a steady continuous flame, with- out seeking to direct this on any object. Holding the blowpipe in tl iii 'Iii ■ I*' ■ t; li I 'I' nli 6 BLOWPIPE PRACTICE. liis riglit liand (with thumb and two outside fingers below, and the index and middle finger above the tube), near the lower extremity, he should let the inner part of his arm, between the wrist and the elbow, rest against the edge of the table at which he ojierates. The jet or point of the blowpipe is turned to the left, and inserted either into or against th6 edge of the flame, according to the nature of the operation, as explained below. After a lew trials, when sufficient skill to keep uj) a steady flame has been acquired, the point of the flame may be directed upon a small splinter of some ea.sily fusible mateiial, such as nati'olite or lepidolite, held in a pair of forceps with platinum tips.* Some little difficulty will probably be experienced at first in keeping the test-fragment exactly at the flame's point ; but this, arising partly from irregular blowing, and partly from the beginner feeling constrained to look at tlie jet of the blowpipe and the object simultaneously, is easily overcome l)y half an-hour's practice. A small cutting of metallic tin or copper supported on a piece of well-burnt soft-wood charcoal can be examined in a similar manner. In these experiments, the beginner must be careful not to operate on fragments of too large a bulk. Th'> smaller the object submitted to the flame, the more certain will be the results of the experiment. In out-of-the-way places, the common form of blowpipe described above is frequently the only kind that can be obtained. It answers well enough for ordinary operations, but the moisture which collects in it, by condensation from the vapour of the breath, is apt to be blown into the flame. This inconvenience is remedied by the form of construction shewn in the annexed figures, in which the instrument consists of two principal portions : a main stem closed at one end, and a short tube fitting into this, at right angles, near the closed extremity. The short tube is also commonly provided with a separate jet or nozzle of platinum. In this case, the jet can be cleaued by simple ignition before the blowpipe-flame, or over the flame of the spirit-lamp. In the variety of blowpipe known as " Black's B}ow])ipe," Fig. 2, the main tube is usually constructed of japanned tin-plate, and the in- * If forceps of this kind cannot be i>rooured, a pair of steel forceps with fine i>oints, auch as watchmakers use, may serve as a substitute. It will be advisable to twist some silk thread or fine twine round the lower part of these, in order to protect the fingers. The points must be kept clean by a file. I i I VAUIOUS FORMS O'' BLOWPIPE. «triiment is thus sold at a clieap rate. Mitscherlich's Blowpipe, Fig. 3, consists of three separate pieces wliich fit together, when not in use, as shewn in Fig. 4. This renders it as portable as an ordinary pencil- case. Fig. 5 represents Gahn's or Berzelius's Blowpipe, with a Fi;,'. 2. Fig 3. Fv^. 4. Fiff. .'■). trumpet-shaped inouth-piece of horn or ivory as devised by Plattner* This mouth-piece is j)laced, of cour.se, on the outside of the lips. It is preferable to the ordinary mouth-piece, but is not so readily used Ijy the beginner. In length, the blowpipe may vary from about seven- and-a-half to nine inches, according to the eyesight of the opeiutor. §3. ACCESSORY APPLIANCES AND REAGENTS. In addition to the blovtrpipe itself, and the forceps described above, a few other instruments and appliances are required in blowpipe operations.* The principal of these comprise ; a blowpipe-lamp (see under § 4) : some well-burnt, soft-wood charcoal, and a thin narrow saw-blade to saw the charcoal into rectangular blocks for convenient «se ; a few pieces of platinum wire, three or four inches in lengtli, of about the thickness cf thin twine, to serve as a support in fusions with borax, t.,! 8 BLOWPIPE PRACTICE. ^:!| li' I!" I water in minerals (see l)elow) ; a sniali haniiner anil anvil, or piece of hard steel, half-an-inch tliick, polished on one of its faces; a triangular file ; a l»ar or horse-shoe magnet ; a pen-knife or small steel spatula ; tv small agat(i pestle and mortar ; a small spirit-lamp ; a platinum spoon ; a small porcelain capsule with handle ; and eight or ten turned wooden hoxes or small stoppered bottles to hold the blowpipe reagents. These latter are employed for the greater part in tiie solid state, a condition which adds much to their portability, and renders a small quantity sutHcient for a great number of experiments. The principal comprise : sodium cai'bonate or bicarbonate, used largely for the re- duction of metallic oxides, and detection of sulphides and sulphates, manganese, &c., as explained below ; sodium biborate, or borax, used principally for fusions on the platinum wire, many substances com- municating peculiar colours to the glass thus formed ; and phosphate of sodium and ammonium, commonly known as microcosmic salt or phospiior-salt, used for the same purposes as borax, and also for the detection of silicates and chlorides, as explained further on. Reagents etc., of less connnon use, comprise : nitrate of cobalt (in solution^ ; potassium Insulphate ; black oxide of copper; chloride of barium; metallic tin; bone ash; litharge, or finely granulated lead or lead foil ; strips of yellow turmeric-paper, and blue and red-litmus paper ; with a few other substances of special employment, mentioned under J G, below. STRUCTURAL PARTS AND CHEMICAL PROPERTIES' OF FLAME. The effects produced by the blowpipe cannot be properly under- stood without a j)reliminary knowledge of the general composition and structural parts of Flame. If the flame of a lamp or candle, standing in a place free from draughts, be carefully examined, it will be seen to consist of four more or less distinct parts, as shewn in the annexed diagram, Fig. fi. A dark cone, a, will be seen in the centre of the flame. This consists of gases, com- pounds of carbon and hydrogen, which issue from the wick, but which cannot burn, as they are cut off from contact with the atmosphei'e. A bright luminous cone surrounds this dark central portion, except at ita Fig. 6. ! 1 THE BLOW PI PK KLAME. » extreme base. In tliis bright coiui the carlton, or a [)orti»)ii of it, sejtarate.s ■ t'roin the hytliogen of the gaseous coiuikhhuIh |niiii|io(l up by the wick. Tlie carbon becomes ignited in the foi ni of minute pai'ticles,* and these, witli the liberated hydrogen and undecomjiosed gas, are driven }>artly outwards, and partly «lownwards or into the blue cup-shaped portion wiiich lies at the base of the (iaine. At this latter spot, the carbon, meeting with a certain supply of dvygen, is converted into carbonic oxide, a compound of eipial combining-weiglits of carbon and oxygen. Finally, in the flame-bonier or outer envelo|)e, of a pale pinkish colour, only discernible on close inspection, complete combustion i.e., union with oxygen, of both gases, carbon and hyiirogen, takes place. The carbon burns into carljo o acid or carbon tlioxide, a conipound of two comlnning weights of oxygen with one of carl)on ; and the hydrogen, uniting with oxygen, forms a((ueous vapour. If a cold and polished body, for example, be brought in contact with the edge of a flame of any kind, its surface will exhibit a streak or line of moisture. These different parts of flame, possess, to some extent, ditteivnt propt^rties. The dark inner cone is entirely neutral or inert. Bodies placed in it become covered with soot or unburnt carbon. The lumi- nous or yellow cone possesses reducing powers. Its component gases, requiring oxygen for their combustion, are ready to take this from, oxidized l)odies placed in contact with them. This luminous cone, liowever, in its normal state, has not a sufliciently high temperature to decompose oxidized bodies, except in a few special cases ; but it* temperature, and consequently its decomposing or deoxidizing ))Ower, becomes much increased by the action of the blowpipe, as shewn below. The blue portion of flsime pos.sesses also reducing powers, but of com- paratively feeble intensity, as the carbon is there able to obtain from the atmosphere a partial supply of oxygen. Finally in the outer or feebly luminous envelope, in which complete combustion takes place, the flame attains its highest temperature ; and, having all the oxygen it recpiires from the surrounding atmosphere, it exerts an oxidizing influence on bodies placed in contact with it, since most bodies absorb oxygen when ignited in the free air. In subjecting a body to the action of the blowpipe, we seek : ( 1 ) * Krank'.and has suggested that the luminosity of flame may not be due to solid carbon, particles, but to the separation of dense hydrocarbons. 10 BLOWPIPE PRACTICE. \i^ ■ !| I ,i!r I ■' I Fiir. to miHo its temiKM'iitnre to in higli a dogree us possilile, ho uh to test the i-olativo fusibility of the Hul>8tiiuo«' ; or (2) to oxidize it, or cause it, if nil oxido, to coinl»iiu> with a hirger amoti. . of oxyg a lower degroc of oxidation. The first and second of tho.se effects may ho produced hy the same kind of flame, known as an oxidating flame (or O. ¥.), tiin position of the substance Ijeing slightly diiforent ; whilst the third effect is obtained by a reducing flamo (or H. F.), in which the yellow portion is developed as much as po-ssiblo, and the substance kept -within it, so as to be cut off from contact with the atmosphere. An oxidating and fusion flamo is thus produced : — the point of the l)low[)ipe is in.sertt'd well into the flame of the gas-jet, lamp or candle under use, so as almost to touch the surface of the gas-burner or wick. The deflected flame is thus well supplied with oxygen, and its reducing or yellow portion becomes obliterated. It forms a long narrow blue cone, surrounded by its feebly luminous mantle. The body to be oxidized sliould be held a short distance beyond the point of the cone, as in Fig. 7 ; b Hiiiiii' tiiiif. tlic tciiiiicriituro is riiisnd HuHicioiitly liij^li to pfoiiiotc rciliictioii. As ii goinMiil rul«s ItotlicH suhjuctetl to u n'(lufiiig tn'iitiiuMjt slioiiM l»o HupporttHl on cliiirooiil. For onlimiry pxpnrinuMjtM, hiicIi uh testing tlio roliitivo fusibility, Ac, of inineriilH, tli(5 hlowpipc may In; used witli tlio tiame of a coiniiiou caiulle. Tlio wick of the cniullo shoiiKl he kept rather short (hut not 8o as to weaken the flame), and it should ho turned Hliglitly to the left, or away from the point of the l)lowpipe, the stream of air being blown along its surfaces A lamp Ham*;, or i,hat of coal gas, however, gives a hi^dlor temperature, and is in many respects prefer.ible. The upper part of the wick-holder (or jot, if gas be used) should be of a rectangular or fattened oblong form, with its surfacf; sloping towards the left at a sHght angh'.* Kitliei' good oil, or, better, a mixture of about 1 i>art of spirit of turpentine, or benzine, with 6 parts of strong alcohol, may be used with the lamp. If the latter mixture be used, equal volumes of the two ingredients must be first well shaken up together, and then the rest of the alcohol added. If tlio wick crust rapidly, the turpentine will be in excess, in which case another volume of alcohol may be added to th<; mixture. The best form of portable lamp, however, is a flat, shallow, circula: or oval, metallic box, fed l»y solid paratHne. The lamp u.sed by the author is a little over half-an-inch deep, and about an inch and a half in diametei', stamped out of a solid piece of tinned iron. The wick- holder is I detached piece of brass vabiug, nealy half an inch in diameter and a little higher than the dej th of the box. The bottom is scalloped or kuotched slightly. This carries a .short, thick wick, wliich gives an excellant flame and is very durable. Most of the paratHne blowpipe-lamps are made too deep, and do not draw well. When in use the lamp is placed upon the edge of the blowj)ipe-ca.se, or on a small block of wood or other object, so as to be raiseci sufficiently above the test-sul)stance ; and after use, but whilst still hot, it is refilled by slicing into it a piece of parafiine, or dropping into it some cuttings from a common paraffine candle. *A convenient fl.iine for blowpipe use is that of a .small ISiinsen burner into which is ■dropi)ed a narrow tu')e (soniewhut longer than the tube of the burner, and with sloped anil flattened upper surface), to cut off the sup|i1>' of air and produce a luminous flame. This acces- sory tube is of course to be removed when bull)-tubes or solutions are heated, or when a sub- stance is ignited without the aid of the blowpipe. 12 nr.OWI'll'K PKACTICK. , I HLOWPIPK OPKIIATIONS. Tlio followiiijj an) hotiio of the more gt'jmriil o|H'iiiti()iiH n'(|iiinil iit l)l()w|)i|K' |»nictioi|)e iii tlio (^\alllinatioll or arialvHiH of minorals. A t'o.w adtUtional o|tonitioiiH of Hpttcial eiiiploy- inent aro rofmrod to in a HiiltHoqiuuit Hcction. (1) IViK Fmion Trial. — \\\ order to aHcortain tlio relative fiiHiliility of a Hiilwtance, wo oliip oH' a aiiiail particle, by the liainmer or cutting j)lierH, and (ixposo it, eitliei- in tlio platinnni-tipped forcoph or on oliar- coal, to the point of tlio blno tlanio (Fijj. 7, above). If tlu! HubHtanco be easily reduced to niotal, or if it contain arseiiic, it must be sup- ported on charcoal (in a snuill cavity made by the knifepoint tor its reception*, as substances of this kind attack platinnin,* I'.i other cases, a thin and sharply-pointed splinter may V)e taken up by tho forceps, and exposed for about half-a-minute to the action of the flame. It ought not to exceed, in any case, the size of a small carraway seed — and if smaller than this, so much the better. If fusible, its point or edge (or on charcoal, the entire mass) will become rounded into a bead or globule in the course of ten or twenty seconds. Ditficultly fusible substances become vitrified only on the surface, or rounded on the extreme edges ; wliilst infusible bodies, though often changing colour, or exhibiting other reactions, preserve the shaipness of their point and edges intact. The more cliaracteristic j)henomena exhibited by mineral bodies when exposed to this treatment, are enumerated in the following table : f (a) The test-fragment may "decrepitate " or fly to pieces. Example, moat specimens of galena. In this case, a larger fragment must be heated in a test- tube over a small spirit-lamp, and after decrepitation has taken place, one of the resulting fragments can be exposed to the blowpipe-flame as directed above. Decrepitation may sometimes be prevented if the operator expose the test- fragment cautiously and gradually to the full action of the flame. "Ill order to prevent any risk of injury to the platinum forceps, it Is advisable (even if not strictly necessary in all cases) to use charcoal an a support for bodies of a metallic asjteot, as well as for those which exhibit a distinctly coloured streak or hijrh specific gravity. tUlowpipe operations, as described in this section, are not intended to serve as a course of analysis Merely a few examples, therefore, are given in illustration of their effects. For plan of Analysis, see § 7. , . ffii OPEHATIONS. 13 t (/») The tfdt-frft^inenti may cliiingu colour (with or without fiirint?) nml liuoomu nttrat'tiil)!)' )>>' a innKiict lvxaiii|iU>, carbouato of iron. 'I'hiH Iiucoiiich lii'Ht red, then lilnck, ami iittraitH tlir rna^jiiet, hiit dot-H not timo. Iron pyritfH, on tlio other hand, heconiett Ittauk and magnetic, hut fiiHCH aUo. ('■) Thu tuHtfragnient may colour the Harno. TIiuh, must copper and nil thallium compounds impart a rich green colour to the Maine ; coinpoiindH in which tellurium or antiin<ec(mio caustic. Kxample, calcic carl.'onate. The carhonic acid is huriied olF, and caustic lime romainu. This restores the blue colour of reddened litmus paper. (i) The teat-fragment may take Hre and burn. Kxample, native sulphur, ciniiaimr, common bituminous coal, &c. (/) The test-fragment may be volatilized or dissipated in fumes, either wholly or partially, and with or without an accompanying od(mr. Thus, grav .*ntimony ore volatilizes with dense white fumes ; arsenical pyrites volatilizes in part, with a strong odour of garlic ; common iron pyrites yields an odour of brimstctne ; and 80 forth, hi nuiny cases the volatilized matter becomes in great part deposited in an oxidi.ied condition on the charcoal. Autimonial minerals form a white deposit or incrustation of this kind. Zinc compounds, a deposit which is lemon-yellow whilst hot, and white when cold. Lead and bismuth are indi- cated by sulphur-yellow or orange-yollow deposits. Cadmium by a, reddish brown incrustation. (7) The test-fragment may fuse, cither wholly, or only at the point and edges, and the fusion may take place (juietly, or with bubbling, and with or without a previous "intumescence" or expansion of the fragment into a caulitiower-like mass. Most of the so-called zeolites, for example (minerals abunilaut in trai) rocks), swell or curl up on exposure to the blowpipe, and then fuse (juietly ; but some ; as prehnite, melt with more or less bubbling. (/«) The test-fragment may remain unchanged. Example, quartz, and various other infusible minerals. (2) Treatment in the Flask or Ihdh-Tiihe {The Water Test). — Minerals are frequently subjected to a kind of distillatory process by ignition in .small glass tubes cloned at one end. These tubes are of two general kinds. One kind has the form of a small flask, and is commonly known as a '* bulb-tube." Where it cannot be procured, a small-sized test- tube may supply its place. It is used piincipally in testing minerals for water. Many minerals contain a considerable amount of water, or 14 BLOWPIPE PKACTICE. if U ;l: the elements of water, in some unknown physiciil condition. Gypsum, for example, yields nearly 2 1 |>er cent, of water. As the presence of this substance is very easily ascertained, the water test is frequently resorted to, in practice, for the formation of determinative groups, or separation of hydrous from anliydrous minerals. The operation is thus preformed. The glass is tirst warmeil gently over the Hame of a small spirit-lamp to ensure the absence of moisture, and is then set aside for a few moment.'! to cool. This effected, a piece of the sub- stance under examination, of about the size of a small pea, is i»liiced in it, an»l ignited over the spirit-lamp — as. shewn in the annexed figure — the tube being lield in a slightly inclined position. If water be present in the mineral, a thin tilm, condensing rapidly into little drops, will be depositetl on the neck or upper part of the tube. As soon as the moisture begins to shew itsolf, the tube must be brought into a more or less hoiizontal position, othei'wise a fracture may be occasioned by the water flowing down and coming in contact with the hot part of th& glass. The neutral, acid, or alkaline con- dition of the water, can be determined by slips of blue and red litmus l)aper. A mineral may also be examined for water, though less con- veniently, by ignition before the blowpipe-flame in a piece of o\)cn tubing, as shewn in Fig. 10. To prevent the tube softening or melting a sti i|> of platinum foil may \)e folded around it where the test-fragment rests. The •■'itf. !"• latter is pushed into its place by a thin iron wire. The moisture condenses on each side of the t'lst-matter. (3) Treatment in Closed Tubes, proper.— In addition to the flask or bulb-tube, small jueces of narrow glass tubing— closed, and sometimes drawn out to a point, at or.e extremity — are frequently used in the examination of mineral bodies. The substance is ignited (either o'^ne. FiK'. 9. M OPERATIONS. 1» or mixed with drv sodium carl>omito or other Hux) at the closed eiul of the tube. After the inswtion of the test-siilistauce, the upper part of the tube must be cleanetl by a piece of .soft paper twisted round an iron wire, or V»y the feather end of a osite(i. Skb §6. (19). OFERATIONif. 17 Sulplvr into sul- ;er taken d, which drons on ilphurous ecognized i), as well noistened ise white (quired in magnesia, applicable possess a jubstante, fter wards moistened in water), »eing held carefully fine blue flesh-red e of tin, a grey, )roduced, obtained, a?.— This constitu- fusiou of the latter vnces dis- md many e of the \ sulphur iri y ij;eiitly. If or arsenic, it should be roasted before being subjected to the action of these fluxes. Metals and metallic alloys, as well as metallic oxides, chlorides, «fec., of very easy reduction, must be examined on charcoal, but in otiier cases it is more convenient to employ a piece of platinum wire as a support. One end of the wire may be inserted into a cork or special handle, or, if the wire be from 2i to 3 inches in length, it may be held in the naked fingers, as platinum conducts heat very slowly. The other end is bent into a small loop or ear. This, when borax or phosphor-salt is used, is ignited by the blowpipe-flame, and plunged into the flux, the adhering portion of the latter being then fused into a glass. If a suflicient portion to fill the loop be not taken up at first, the process must be repeated. With beginners, the fused glass is often brownish or discoloured by smoke, but it may be rendered clear and transparent by being kept in ignition for a few moments before the extreme point of the flame, the carbonaceous matter becoming oxidized and expelled by this treatment. When sodium carbonate is used, a small portion of the flux must be moistened and kneaded in the palm of the left hand, by a knife-point or a small 5i)atula, into a slightly cohering paste, which is placed on the loop of the wire, and fused into a bead. Whilst hot, the soda bead is transparent, but it becomes oi)aque on cooling. The portion of test-matter added to a glass or bead, formed by the.se reagents, must be exceedingly small, otherwise the glass may become so deeply coloured as to appear quite black. In this case, the colour may be ol).served by pinching the bead flat between a pair of forceps, before it has time to cool. It is always aflvisable, however, in the fii*st instance, to take up merely a minute particle or two of the test-substance, and then to add more if no char- acteristic reaction be obtained. The glass, in all cases, must be examined first before an oxidating flame, and its colour observed both whilst the lux is hot and when it has become cold ; and, secondly, it must be kept for a somewhat longer interval in a good reducing flame (Fig. 8), and its appearance noted as before.* With certain sub- stances (lime, magnesia, »fec.,) the borax and phosphor-salt glasses become milky and opaque when saturated, or when subjected to the intermittent action of the flame — the latter being urged upon them in short puffs, or the glass being moved slowly in and out of the flame — a process technically known as flaming. * The colour of the glass ought not, of course, to be examined by the traimnitted li(jht of the lamp or candle tlnnie. Strictly, it should be observed by daylight. 3 18 BLOWPIPE PBACTICE. The colours, &c., coniinunicated to these glasses by the more com- monly occurring constituent bodies, are shewn in the annexed tabular view. BORAX. Colo\ir o( Head after exposure to ail Oxidatini^ Flame. Violet or amethystiue Violet-brown (whilst hot). . Clear-brown (when cold) . . . Blue (very intense) Green (whilst hot) Blue or greenish-blue (cold) . . Green or bluish-green Green (dark) Yellowish or reddish (hot) . . Yellowish-green (\\hen cold). Yellow (whilst hot) Greenish-yellow (cold) Yellowish or reddish Yellowish or reddish Enamelled by flaming Yellow (whilst hot) Pale yellowish (cold) Enamelled by flaming Yellow (hot) Colourless (cold) Enamelled by flaming Yellow (hot) Colourless (cold) Enamelled by flaming Yellow (hot) Colourless or yellowish (cold) Grayish and opa(iue by flaming Coiiipouiids of :- .Manganese Nickel Cobalt }- Copper < . . Cobalt + Iron 1 Copper -I- N ickel ) / Copper -f- Iron . . ) y Chromium Colour of f?cad after exposure to a lU'diiciiiK: Klaiiio. J Colourless, if (juickly cooled. ( Violet-red, if slowly cooled. Vanadium . Iron Uranium . . ...{ Cerium i Yellow or yellowish-red (hot) Yellowish or colourless, and often opaline, when cold . . / j-itamum ^ Tnngstenum . . Molybdenum . . Lead Bismuth , I Silver ' Antimony . . . Yellowish (hot) Colourless (cold) ,. . . Opuque-white when saturated Colourle88(permanentlyclear) Slowly dissolved SeeunderPhosph 'r-salt, below lo Cadmium ) Aluminium > Silicon n'in I . . (^ray and op!i<(ue. . . Blue (very deep). More or less colourless whilst hot ; brownish-red ik opaijue on cooling. Creen or bluish-green. Brownish-red, opaijue, on cooling. Emerald-green, Brownish (whilst hot). Emera'd-green (when cold). Bottle-greeu. .Green (black by flaming). Colourless or yellowish. Opjique-white, if saturated. Yellow or yellowish-brown. Enamelled light-blue by flam- ing. See under Phosp.-salt, below.. Yellow or yellowish-brown. Enamelled by flaming. Sue under Phosphor-salt, below Brown or gray, semi-opaijue, often with separation of black specks. See under Phosphor-salt, below Gray and opacjue on cooling ; but after coutinutd subjec- tion to the flame, the glass becomes clear : the reduced metallic particles either col- lecting together or volatil- izing. Colourless — the reduced metal being volatilized. Colourless : permanently clear. (Tin compounds dissolve in small quantity only. On char- coal, they become reduced to metal, especially if a little carb. sodium be added to th& glass). OPEKATIONS. 19 lore coin- jd tab>ilar >r cNposiire Kliuno. ukly cooled, wly cooled. iless whilst d 'ated with silica or boracic acid, it will remain green in the latter case ; while if the green colour result from the presence of manganese, a violet or amethystine glass will ))e obtaijied. Some other applications of sodium carbt)nute as a blowpijie reiigent will be found under the head of Keaction.s, § G. (8) Redtiction. — Tliis term denotes the process by which an oxidized or other compound is converted into the metallic state. Some com- pounds become reduced by simj)le ignition ; others require for their reihiction the addition of certain reagents ; and some, again, resist reduction altogether. The reduced mental is in some cases so higlily volatile that it cannot be obtained except by a kind of distillatory process. In other cases, one or more fusible globules, or a number of minute infusible grains, are obtained in blowpipe operations. Reducible metals may be thus distributed into three groups, as shewn (with omission of a few metals of rare occurrence) in the annexed table : — A. Yiehlinij metallic ijlohules, — Gold, silver, copper, tin, lead, bismuth, antimony. B Yh'ldbifj Infusible metallic grains. — Platinum, iron, nickel, cobalt, molyl)- denum, tungstenum. C. Yielding metallic vaj)onrs onle obtained. ent will be ,n oxidized Some coin- e for their [ain, resist 3 so highly distillatory a n\imber operations. 3, as .shewn le annexed d, bismuth, bait, molyb- — Mercury, ent in very 3d test-sub- d reducing are vapidly le globules tule. This bility,* «fec. and anti- in a in-ight blowpipe, the wii l).v the fore- t is 8tru('k once tied into discs. surface after subjection to an oxidizing flame. Copper becomes covered with a black film, and tin with a white crrst. Lead and bismuth volatilize more or less readily, and deposit en the charcoal a yellow coating of oxide. Antimony is rapidly volatilized with de- position of a dense white incrustation on the charcoal. It is not, of coui'se, always necessaiy to subject tlie test-substance to a previous roasting (Operation 4, above), but it is always safer to do so. Sul- phur in most, and arsenic in all cases, must be driven off by this preliminary treatment before the actual process of reduction is attempted. When the metal to be reduced belongs to the second group, or if the amount of a fusible metal in the test-substance be leas than 4 or 5 per cent., the operation is ])erformed as follows : A small jiortion of the substance in powder — subjected previously to the roasting pro- cess, if it contain sulphur or arsenic — is mixed witli 3 or 4 volumes of .sodium carbonate (or neutral o.xalate of |)otassium, or a mixture of about erpial parts of sodium carbonate and cyanide of potassium — the latter, it must be remembered, a highly poi.sonous substance), and the mixture is exposed on charcoal to a good reducing flame, until all the alkaline salt has become absorbed. More flux is then added, and the o[»eration is rejieated until the whole or the greater part of the test-uuittev is also absorbed. This effected, the charcoal, where the assay rested, is removed by a sharp knife-point, and carefully groiuid to powder in a small agate mortar or porcelain capsule, whilst a fine stream of water is projected upon it from tinui to time, until all the carbonaceous and other non-metallic particles are gradually washed away. For tliis pnrj)OH0, the mortar or capsule may be placed in the centre of an ordinary plate ; and if the operator be not provided with a chemical washing-bottle, he may use a small syringe, or, in place jf this, a simple piece of glass tubing, five or six inches in length and about the fourth of an inch in diameter, drawn out at one cud to a point. This is filled by suction, and the water is expelled, with the neoessary force by blowing down the tube. The metallic grains or spiingles obtaiut'd by this process must be exanjined by the magnet. Those of iron, nickel and cobalt are magnetic. Sometimes, however, when but a trace or very small percentage of reducible metal is con- tained in the test-substance, its j»resence is only indicated by a few metallic streaks on the sides and bottom of the mortar. Metallic markings of this kind can be moved by a piece of pumice. 55 BLOWPIPK PRACTICE. ! ' § Metallic com poii nils retBi-abie to the third group, yield no metal on charcoal, or l>y other treatment in open contact with tlie atiuoHi)here. Tlie presence of arsenic, however, in easily made known by the gurlic- like odour evolved during fusion with reducing agents (or alon3) on charcoal. Cadmium and zinc may also be recognized by the oxidized sublimiites which they deposit on the charcoal. The cadmium sub- limate is ieddisli-b"own : the zinc sublimate, lemon-yellow and phos- phorescent whilst hot, and white when cold. Mercury forms no incrustation on charcoal ; but its presence in any compound may be. determined by reduction with sodium carbonate or iron-fillings in a glass tube of narrow diameter. A small test-tube or piece of glass tubing closed at one end before the blowpipe, may be used for the experiment. The test-substance, in powdei-, mixed with 3 or 4 vols, of dry sodium carbonate, is inserted into the tube by means of a narrow strip of glazed writing-) )aper bent into the form of a trough, so as to prevent the sides of the glass from being soiled, and the mixture is strongly ignited by the spirit-lamp or by the blowpipe- flame. If mercury be [)resent, a gray metallic sublimate will be formed near the upper part of the tube. By friction with an iron wire, or narrow strip of wood, &c., the sublimate may be brought into the form of fluid globules, which cun be j)Oured out of the tube, and are then easily recognized as metallic mercury. (9) Cupellation. — Gold and silver are separated by this ])roce3s from other metals. The test-metal is fused with several times its weight of pure lead. The button, thus obtained, is exposed to an oxidating fusion on a porous support of V)oneash, known as a cupel. The lead and other so-called base metals become oxidized by this treatment, and are partly volatilized, and partly absorbed by the boneash, a globule of gold or silver (or the two combined) being finally left on the sur- face of the cupel. For blowpipe operations, cupels are generally made by pressing a small quiintity of dry boneash into a circular iron mould, the latter being fixed, when presented to the flame, in a special support consisting essentially of a wooden foot and pillar, supporting a wire stem, with three or four short cross-wires at the top, between which the cupel-mould rests. Instruments of this kind cannot be obtained in remote places, but the process may be performed equally well by pressing some dry boneash into a suitable cavity fashioned at the extremity of a cylindi-ical piece of pumice or well- OPKRATIONS. 23 baktMl clay, or even cliaicoal. The smooth eml of the agate pestle, or a ghiSH button ceiuent»'tl to a cork, or the rouiuleil end of a ghisa stopper, may he used for this purpose. Tlie ciii)el, thus formed, must then be exposed foi- a few moments to the point of tlio blowpipe-flame, so as to render the boneash perfectly dry ; au»l if its surface becDine blistered or be in any way affected dy this drying process, it must be rendered smooth again by pressure with the pestle. The substance to be cupelled must be in the metallic state ; if not in this condition, therefore, it must tirst be subjected to the reducing operation described above. The piece of test-metal, which may weigh about a couple of grains (or from TOO to 150 milligrammes) is wrapped in a piece of j>uro lead-foil of at least four times its weight, and the whole is exposed, on the surface of the cupel, to the extreme )ioint of a clear oxidating' flame. If the substance consist of argentiferous lead, aa obtained from galena, tfec, the addition of the lead-foil is of course uimec(issary.* As soon as fusion takes place, the cupel must be moved somewhat farther from the tlame, .so as to allow merely the outer envelope of the latter, or the warm air which surrounds this, to play over the surface of the globule. By this treatment, the lead will become gradually converted into a fusible and crystalline slag. Wlum this collects in large quantity, the position of the cupel must be slightly altered, so as to cause the globule to flow towards its edge, the surface of the lead being thus ke])t free for continued oxidation. When the globule becomes reduced to about a fourth or fifth of its original bulk, the process is discontinued, and the cupel is set aside to cool.f This is the tirst or concentration stage of the process. Another cupel is then pre|)ared and dried; and the concentrated globule — after ■ In refluciiii,'- jfaleiia, with a view to test the lead for silver liy cuiiellation, the reduction niav lie eoiiveniently perfonned .as follows: a small portion of the jralena, crushed to powder, is liiixed with ahout twice its volume of soie Anwendiint; rtes Li ithrohrs, " etc. ; translation of the 4th edition, by J. U. Whitney; Uoslon, 184.'). 2. " Han'\. ;t. Plattner's " Probirkunst mit dem Luthrohr " '>th edition, by Itichter, 1878. Aniericun translation of 4th edition, by H. B. Cornwall : Xew York, IST.'i. 4. "" rntersuchunjfcn mit dem I.iitlirohr, " by Dr. H. Hartmann : Leipsi^, 1862. '). " Luthrohr-Tabellen, " by Dr. .1. Hirsch- wald ; Leipsitf aud Ileidelberia:, 1875. ti. " Manual of Determinative .Mineralogy and Blowpipe Analysis,'' by Georjfe ,f. Brush: -ind edition, 1878. 7. " I.eitfaden bei (pial. und (|uan. I.cith- rohr-l'ntersuchunxen, " von Bruno Kerl, 2iid edition, Clausthal, 1877. I.andauer's Blowiiipe Analysis, 18i)'2. F'or the determination of minerals, the far-renowned " Tafeln " of Von Kobell (in addition to the work of Prof. Brush, essentially constructed on that of Von Kobell, although with much ampliflcation and addition of new' matter) may be especially consulted. The " .\nleitunit,' zum Bestimmeii der .Mineralien," of Dr. Kuchs,"is also a very serviceable little Book : and some useful tables are triven at the end of E. 8. Dana's excellent " Text Book of Mineralogy. " As rejfarils the Silicates, the Clacis der Silicnte (18C4) by the late Dr. L. H. Fischer contains many original observations, and will be tound a valuable yaiide. 96 ni.OWl'll'K I'llAPTtCR. i4| h 1 1 I. Xon-metalliK. liotilen. — I, ()xy;(»Mi ; 2, Hy. Arsenic ; 20 OHinium : 21, Mercury ; 22, I'lismuth ; 23 Lead ; 24, Thallium ; 2r), Cadmium ; 2(), Zinc; 27, Tin. IV. Flux-col ourhuj nipJuU — 28, Copper ; 29, Nickel ; 30, Cohalt ; 31, Iron ; 32, Tun;,'Htenum ; 33, Molybdenum; 34, Manganese; 35, (thromium; 3G, Vanadium ; 37, ITranium ; 38, Cerium ; 3U, Titanium. V. Achroic Mctnls. — (40, Tantalum ); 41, Aluminium; 42, Clu- cinum ; 43, Zirconium ; 44, Yttrium ; 45, Magnesium. VI. Ffame-culouriuy MpIuIx. — 46, Calci.iin : 47, Strontium ; 4S, JBarium ; 49, Lithium; 50, Sodium; 51, Kalium ; 52, Ammonium. I. — NON-METALLIC nODIES. (1) Oxjfijen. — Although this element occurs so ahundantly as a constituent of mineral bodies, its presence, as a rule, can only be inferred by negative evidence. If a substance be neither one of the few known simple bodies of natural occurence, as golil, carbon, kc, nor a sulphide, selenide, arsenide, chloride, itc, it may be regai-ded with tolerable certainty as an o.xidized body. And if, farther, its examination shew that it is not an oxygen-salt, i.e., a sul|)hate, car- bonate, silicate, or the like, we can then only infer that it must be a simple oxide, either electro-negative or basic in character. All non-oxidized bodies attackable by nitric acid, decompose the latter in taking oxygen from it, and thus cause the evolution of ruddy nitroiis fumes ; but this decomposition is also effected by certain oxides in passing into a higher state of oxidation, as by Cu-0, for exam{)le. Some few , todies, as binoxide of manganese, nitrates, chlorates, 'bichromates, »ikc., give off oxygen on strong ignition. If the-se be ignited (in not too small a quantity) in a test-tube containing at its upper part a charred and feebly glowing match-stem, the latter, as the evolved oxygen I'eaches it, will glow more vividly. These bodies, also, if fused with borax or phosplior-salt, dissolve with strong ebulli- tion ; but carbonates pi-oduce the same reaction. HEACTfONS. 87 Hdlphur ; Iodine ; *J, licoii. Silver. lony ; l\)< Lead ; 24, 0, Colmlt ; meso ; 35, Titaiiiuin. ; 42, CJlu- iium ; 48, iiiuoniuin. ntly KH a ■U only lie one of the irboii, ikc, ! regarded irtlier, its |)hate, car- must be a iipose the \ of ruddy jy certain Cu^l, for chlorates, these be ing at its latter, as »se bodies, mg ebuUi- # :si. (2) Hyilroijfn — 'Phis oleinont, apart from its occurenco in bitumen and other hvdro-carltonacoouH Hubstanci^H, in only present in oxidized minerals. Krom tliese, it is evolved, with o.xy^en, in the form of water, durint,' the ignition of tlio substance. (See Operation 2, § ').) {\\) Sulphur. — Ocfiirs in tlie free state, as " native uulphiir ;" also con)bin(>d with metals in sulphides and siil|>hur-salts ; and in eomltiiia- tion with o.vygi'ii as SO', in the large group of sulphates. Native sulphur is readily inHainable, burning with 1)1 ue flame, and vola- tilizing (with till" well known odoin' of burning brimstone) in the form of sulphurous acid SO-'. Metallic sulphides and siilphur-salts (especially if previijuslv reducfij to powder and moistened into a paste), when roasted in an open tuiie of not too nnrow diameter- give oft' the same compound (SO-), easily recognized by its odour, and by its action on ,i slip of moistened litmus paper placed at the top of the tube, the paper becoming reddened by the acid fumes. In very narrow (as in closed) tubes, part of the evolved sulphur may escape oxidation, and may de| .)sit itself on the inside of tlie tulx' near the te.st-substance. The sublimate, thus foinied, is distinctly red whilst hot, and yellow on cooling. Fron» many arsenical and antimonial sulphides also, a coloured sublimate of this kind, but consisting of As'S'', or 2Sl>'-'S'-f-SlrO', vtc, may be deposited in nariow tubes, especially if the tube be held more or less horizontally. Suli)hides of all kinds, if fused on charcoal with sodium carbonate (or better with soilium carbonate mixed with a little borax) readily form an alkaline sulphide or " hepar. " This smells, when moistened, more or less strongly of sulphuretted hydrogen, and imparts u dark stain to a sih er coin or to paper previously steeped in a solution of lead acetate. A glazed visiting card may lie used as a substitute for the latter. Tlie stain is removed from the silver surface by friction with moistened boneasli . Sulphates fused with sodium carbonate and a little borax (the borax in the case of earthy sulphates greatly assisting the solvent power of of the flux) pi'oduce the same reaction. This reaction is of course produced also by sulphites (which do not occur, however, as minerals), and by bodies wliich contain selenium or tellurium in any form. Sul))hites, trt^ated with hydrochloric acid, evolve sulphurous acid, easily recognized by its smell and its action on litmus paper ; and, in ■fcU.-:.^,^^^.^^ iia 28 BLOWPIPK TKACTICE. I u acid solutions, they yield no pri'cipitute with chloride of bariiuu Sulphates, on the other hand, emit no odour of SC wlicn treatetl with hydrochloric acid ; and chloridt^ of barium ])roduces an insoluble precipitate in their acid or other solutions. Boilies containing selenium, are distinguished from sulphur compounds by the strong odour, resembling that of "cabbage-water," which they evolve on Ignition. The efficacy of the sulphur-test is imperilled however by two causes: (1), the ditticulty, in many places, of i)rocuring sodium car- bonate perfectly free from traces of sulphates ; ami (2), the very fre- quent presence of sulphur in the flame, where gas is used in blow- pipe operations. The first defect may be remedied (if the soilium carbonate, employed alone, produce the reaction) by substituting, as proposed by Plattner, potfissium oxalate for i.he test, as that salt is generally pure and free from sulphates ; and the flame of a cautUe, or an oil or spirit-flame, ma}' be useil in thi.s experiment when thfr gas flaiue is fouiul by trial with pure fluxes to give the reaction. Sulphides of natural occurrence aro tlistinguished from most sulphati's, by emitting sulphurous acid (or, scrictly, by emitting sulphur vapour which combines with atmospheric oxygen ami forms sulj)hurous acid) on ignition ; although in the case of certain sulphides, (blende, nuilybdcn'te. itc. ) a i^frong reaction is only produced by the ignition of the substance in powiler. Most natural sulphides, also, present a metallic aspect ; or otherwise are highly inflammable (orpinient, cinnabar, itc); or yield a strongly coloured streak. Ligiit- coloured varieties of zinc blemle are the only exception. On the other hand, no sulphate possesses a metallic aspect; ami, in all. the streak is either colourless or verv liglitlv tin.ed. (4) Si'h'niion. — Met with only, as an essential component, in a few minerals of very rare occurrence, but occasionally replaces a minute portion of the sulphur in galena and other sulphides. Volatilises with blue flame and emission of stiong odour of ilecomposing vegetable matter or "cabbage water," by which its })resence is easily recognized. All selenides emit this odour on ignition, and form a "hepar" (as iu the case of sulphur and tellurium) by fusion with sodium carbonate. This, when moistened, imparts a dark stain to the surface of a silver coin. In the oihju tube, selenides form near the assay-matter a dark steel-gray deposit, and, fartlier off, a red coating. PKACTIONS. 29 if barium Oil ted with insoluble containing ;1k' strong evolve on •V by two Kliuni oiir- (? very tVe- il in blow- lio sotliiini itutiny;. us hut salt is a eaiuUe, when the- ;tion. foni most r emitting iiml forms sulphides, ed by the ides, also, tiammablo Ligiit- the otiier the streak t, in a few a minute Volatilises vegetable eoognizt'd. ar " (as iu .•arbonate. )f a silver ter a dark (5) yitro(fen. — Found only, lus regards niir.ei-als proper, in an oxidized condition (Xi'-O') in nitrates. These are soluble or sub , soluble in water ; a..d they deflagrate when ignited on charcoal or in contact with other caibonaceous bodies. Heated with a few drops of sulphuric acid (or fused with jHJtiussium bisulphate) in a test-tube, nitrates evolve also ruvldy fumes of nitrons acid ; and many nitrates, moistened witli sulphuric acid, impart a dull green colomtion to the fhiine luirder. (I)) Cfi/oriiie. — Oecnra, among minerals, in combination with various bases, forming the group of chlorides. In these, its presence is very easily recognized by the bright azure- blue eoloiiition of the tlame-border which originates during the fusion of a chloride with a bead of phosphor-salt coloured by oxide of copper. The fusion may be performed on a loo]> of platinum wire, the })ho.s])hor-salt being tiist fused with some black oxide of copper into a somewhat deeply coloured glass, and the t?st-substance, in the form of ]>owder, being then added. Or the fusion may be matle on a thin copper-wire with plios])her-salt alone, the .d of the wire being cut oil' after each exptMiment. By this treatment, chlorides become decomposed, ami chloride of coi)per is formed. The latter conipoimd rapidly volatilizes, and imparts a i-emarkably vivid bright-blue colour to the flame. The coloration soon pas.ses, but can, of coursi , be reneweil by the add f\on of fresh test-matter to the bead. Care must be taken to use pure phosphor-salt, as that reagent, unless carefully made, is fretpuMitly found to contain ti-aces of ch' iride of sodium. Many other chlorides nlso volatilize more or le.st, readily on strong ignition : NUH^l, KCl, NaCl ; and chlorides ot Hg. Sb, Bi ; Pb, Cd, Sn. Zn, i\:c., arc ex- amples. Oxidised chlorine-co>i>pounds do not occiv as minerals, but it may be stated that chlorates produce the same flame-reaction as chlorides, when fusetl with phosphor-salt ai\d copper oxide. All chlorates, however, detonate like nitrate-., only mon> violently, when ignited in contact with carbonaceous botlies ; and they turn yellow, decirpitate, and emit greenish fumes when wanned with a few drops of sulphuric acid (or fused with potassium bisulphatt^) in a test-tul)e. The fumes smell strongly of chlorine, and bleach moisteneil litnnis paper. Most chlorides, when thus treated with sulphuric acid, eflervesce and give otV white fumes of hydrochloric acid. 30 BLOWPIPE PRACTICE. ii (7) Bromine. — Only known, among minerals, in some rare silver bromides. Its blowpipe reactions closely resemble these of chlorine, but the flame-coloration of bromide of copper is a bright-blue with green streaks and edges. A small sharjdy-pointed tlame is required to shew the reaction properly ; and care must be taken not to add the test-matter to the cupreous phosphor-salt bead until all traces of the green coloration, arising from the oxide of copper, have disap- peared. Heated in a test-tube with sulphuric acid (or fu-t.'d with large excess of potassium bisulphate), most bromides yield brownish or yellowish-red, strongly smelling vapouis of bromine. Bromates pro- duce the same reaction, but this is accompanied by sharp decrepitation; and when fused on charcoal they detonate more or less violently. (See Appendix, No. 20). (8) Iodine. — In nature, iodine occurs only in one or two rare minerals, compounds of iodine and silver, or iodine, silver, and mercury. In these, as well as in all artificial iodides, its presence may be recognized by the vivid green coloration imparted to the flame during fusion with a cupreous phosphor-salt beau, The test-matter must not be added to the bead unhil the copper oxitle is completely dissolved in the latter, and all traces of green (commiuiicated by the CuO) have disapi)eared from the flame. Iodides, also, when warmed with a few drops of sulphuric acid (or fused with exces8>of potassium bisulphate) in a test-tube, evolve strongly smelling violet-coloured vapours, which imi)art a deep blue stain to matters containing starch. A strip of luo" "tened tape or starched cotton may be held at the top of the tube. lodates exhibit the same reactions, but deflagrate when ignited with carbonaceous bodies. (See Appendix, No. 20). (9) Fluorine. — This element, as an essential component of minerals, occurs in combination w'th calcium and other bases, forming the various fluorides. It is also largely pi-esent in topaz, prolmbly in combination with silicon and aluminium ; and it occurs, ti;('U,;;h in smaller proportion, in chondrodite, and as an accidental oi. in. ?- atial component in many other silicates. Its presence is reveaL^d in ordinary fluorides by warming the substance in powder, with a few drops of sulphuric acid (or fusing it with potassium bisulphate) in a test-tube, when stifling fumes, which strongly corrode the inside of I he glass, are given off. The potassium bisulphate should be fused first and the test-matter then added. The conosion is to be looki'd i'oi: REACTIONS. ai rare silver 3f clilorine, >blue witli is required not to add II traces of lave disap- with large [•owuLsh or Hiiates pro- repitation ; utly. ( See ' two rare silver, and esence may I the tlaine test-matter comi)letely ited by the eii warmed )Otassiiim et- coloured ling starch. it the top t.rate when minerals, rniing the ;'!'.i.i!)ly ia i,<.ii...;h in i. o iitial eaL^'l in. ith a lew late'; in a side of the 'used Hist ooki'il foi: immediately above the assay-mixture. It is best observed alter the tube has been washed out and thoroughly dried. Or, the trial may be made in a platinum crucible covered with a glass plate: on washing the test-tube or glass, and drying it, the corrosion is rendered visible. When fluorine is ))rese.nt in very small quantity in a substance, it is f'eueraliy driven off the more readily, often l)y the mere ignition of the substiince (either alone, or with previously fused phosphor-salt) at one end of an open narrow tube — the Hame being directed into the tube, so as to decompose the test-matter and drive the expelled gases before it. A slip of moistened Brazil-wood paper, placed at tiie mouth of the tube, is rendered yellow. Many silicates which contiiin. only traces of fluorine lose their polish when strongly ignited per se in the form of a small splinter ; but in certain Huo-silicates, as topaz, in which fluorine is largely present, the fluorine-reaction is not readily manifested. The best method of detecting it is to fuse the assay- matter in flne powder with a fused bead of phosphor-salt on a lunit slip of platinum foil inserted into one end of a piece of open tube whilst the flame is driven strongly up the latter. (10) Phosphorus. — Occurs, in minerals, in an oxidized condition only, i.Ts., as phosphoric acid (or anhydride) in the gi-oup of phosphates.* It is assunifd to lie in this coinlition siiii|ily heoause pliosi)hcUi.'9 ^ivo tlie known rouctioiis nf i)hos])liorio iiciil or phosphoric aiihydriiU-, .ilthougli thusi' inactions may, of course, he iiiodifie'l to some extent hy the presence of otlier hodies. In hke maimer, when iron is present in an oxidized hody, we assume that it is present in the condition of KeO if the suhstance ;rive the known reactions of that conii)ounlest and most practically useful way of statinjr, either verbally or by symbols, the composition of limestone and other mineral bmlies, is surely that which makes known to us at once the components into which the body readily splits up or decomposes, or which char.acterize it directly by their reactions. In all commercial analyses this method is neces.sarily followed. It is adhered to therefore in the i)re.sent handtirxik. It may lie urtred that a formula of the kind represented by C'aO, Co- asserts too iimch, an,, 8i(),, .Sit>„, etc., etc., are present in the substances to which these fornmlie refer. To take another illustration. A student h.-vs two. "Ml •I'l! f. 32 BLOWPIPE PKACTICE. .4 i As first ))ointed out by Fuclis, these bodies, when moistened with sulphuric acid, impart a distinct green coloration to the flame-border and many produce this reaction per se. A closely similar coloration, however, is communicated to the flame by borates (when moistened with sulphuric acid), as well as by bod'os containing barium, copper, ' )' ■ t ■i';:i; ■■1 m ■■A I; other bodies, may thus be easily recognized. (See Appendix, No. 19). It should be remembered, however, that bodies which evolve oxygen on ignition, produce also a strong effervescence by fusion with borax ; bixt, with the excej)tion of binoxide of manganese, very few of these bodies are of natural occurrence. As a confirmatory test, the suspected carbonate may be warmed with a few drops of dilute hydrochloric acid in a test-tube.* (13) Silicon — This element occurs in nature only in an oxidized condition, as Silica, SiO'-. Tl)e latter compound, in the form of quartz and its varieties, is the most widely distributed of all min- ei'als. In the various opals, it occurs in a colloid and mostly hydrated condition ; and in combination with bases (esi)ecially with Al'-O'*, Fe-'O^ CaO, MgO, FeO, Na'-O, and K-'O), it forms the large groups- of silicates. In the simple state, silica is quita infusible in the ordinary blowpipe-flame. With sodium carbonate it dissolves with effervescence (due to the expulsion of CO- from the flux), and it forms with that reagent, in proper proportions, as permanently clear glass — i.e., a glass that remains clear on cooling. To obtain this, the flux should be added little by little, until perfect fusion ensue : with too much flux, the bead is opaque. Borax attracts silica very slowly, and in phosphor-salt it is still more slowly attacked. A })ortion may be taken up by the hot glass, but this is precipitated on cooling, and the glass becomes opalescent. (See Ap))endix, No. 15), Silicates vary greatly in their comportment before the blowpi[)e, the Aariation depending chiefly on the relative proportions of silica and base, and on the nature of the base. Many silicates are infusible ; others become vitrifled on the thin edges; and others, again, melt more or less readily^ — most of the so-called zeolites (hydrated silicates of alumina, lime, soda, uc, especially characteristic of trap rocks) — exhibiting the phenomenon of intumescence. Silicates, as a rule, are very readily detected by their comportment with phosphor-salt : the bases are gradually taken up, whilst the silica remains for the greater jnirt undissolved, forming a "silica-skeleton." This is seen as a diaphanous, flocculent mass (of the shape and size of the test-fragment) in the centre of the hot bed. A small portion of the silica, or in one or two exceptional cases the greater part of it, may be dissolved with tlie " If only n inoinentar.v effei'vesfeiife ensue from this treatment, the sul)stiince, in place of lieiiiK a tarboiiate proper, will I'oiitaiii simplj' intermixed civ'.iute or other carbonate. This ic- especially to he reiDemherecl by students inexperienced in mineral detenninatioiis. REACTIONS. 35 K, No. 19). Ive oxygen ith borax ; w of thesft 3 suspected jftlrochloricr n oxidized e form of )f all inin- y hydrated 'ith Al-'O'', rge groups- ble in the iolve.s with nd it forms ear glass — is, the tlux : with toa dowly, and ion may be ig, and the icates vary ) variation ase, and on jrs become ess readily y miua, lime, biting the ery readily bases are ■eater i>art iauhanous, ent) in the one or two with tlie loe, in place of Dimte. This is. bases, but this precipitates as the glass cools, and renders it senu- translucent or opalescent. Practically, silicates are readily dis- tinguished from phosphates, carbonates, sulphates, «fec., by these re- actions with phosphor-salt : namely, very slow or partial solution, and formation in most cases of a silica skeleton or opalescent glass. The trial is best made on platinum wire, and the test-substance should be ailded, if possible, in the form of a thin scale or splinter. (See Appendix, No. 15). II. — UNOXIDIZABLK METALS. As regards their blowpipe reactions, the metals of this group fall into two series: Infusible metals, com[)ri.sing platinum (with palladium, kc); and Fusible metals, comi)i"ising gold and silver. Strictly, silver absorbs a small amount of oxygen when fused in contact with the atmosphere, but +he oxygen is evolved as the metal solidifies. It is this which caus(3S cupelled silver to "spit" or throw out excrescences, if the button be iillowed to cool too quickly. All the metals of this group ({talladium slightly excepted, retain a bright surface when exposed to the action of an oxidating flame. (14) Platinum. — Occurs in the metallic state, alloyed with iridium, and commonly with small (juantities of other metals, as with arsenic in the lately discovered Sperrylite. Practically, infusible; but the point of a wire of extreme tenuity may be rounded in a well-sustained flame. Not attacked by the blowpipe fluxe.s. (See Appendix : No. 21). (15) Gold. — Occurs principally in the metallic state, alloyed with variable proportions of silver. Also, but far less commonly, com- bined with mercury in some vai'ieties of native amalgam, and with tellurium in some rare tellurides. In the metallic condition, or p(!r- haps as an arsenide or sulphide, it is present likewise as an accidental component in many examples of arsenical pyrites, iron pyrites, coi)pt'r pyrites, zinc blende, »fec., in the proportions of a pennyweight or two, to several ounces, per ton. Fuses readily on charcoal before the blowpij)e, and retains its bright surface in an oxidating flame. Not attacked by the blowpipe fluxes. Separated from silver by fusion with bisulphate of potash in a platinum spoon, the silver becoming di-ssolved ; or (if the silver be not in too small a quantity) by dilute nitric acid moderately warmed. In the latter treatment, the gold sepai'aces as a dark mass or powder. This assumes a yellow colour and 30 BLOWPIPE PRACnCK. i'f^: «;«■ metallic lustre by compression with a glass rod or other hard body. An alloy of goUI coiituining but little silver is merely blackened by the acid. In this case it may be foUhsd in a small piece of pure sheet lead with a piece of silver of al)out twice or three times its size, and cui)elled before the blowpipe (Operation 9, § 5). The alloy is then readily attacked l)y the acid, and the silver is dissolved out. (See Appendix : No. 21). (16) Silver. — This metal occurs in nature under various conditions : principally in the simple state, as an amalgam with mercury, and as a sulphide, sulphantinjonite, sulphaisenite, and chloride : less com- monly as a .selenide, telluride, antimonide, sulpho-bismuthite, bromide and iodide. Tt occurs also as an " accidental component " in many varieties of iron pyrites, «kc., and in almost every example of galena.* Metallic silver melts readily before the blowpipe, and the fused globule retains a bright surface after exposure to an oxidating flame. In a prolonged l)last a slight brownish-red sul)limate is deposited on the charcoal, the sublimate being more distinctly red in the presence of lead or antimony, l)ut in the latter case it is scarcely ob.servable until these metals become lor the greater part volatilized. Silver oxide becomes rapidly reduced on charcoal. It is dissolved by borax and pho.sphor .salt, forming glasses which are indistinctly yellowish whilst hot, and opaline or opafpie-white on cooling. Metallic silver is attacked with similar results by these fluxes, and also by bisulphate of i)otassium. In all ordinary cases the presence of silver in minerals is best detected by leduction an< aiui 1 ('2'2) liixmnth. Occurs in nature chietly in the simple uietailio state. Found also, lait more sparini,dy, in comliiuation witii tollu- rium, selenium, ami sulpliin-, and with bases in sulpho-bismuthites. OccaHionaily, likewise, in an oxidized condition (Hi'-<)'') hh bismuth ochre (commoidy mixed with somo carlM)nato of Itisnuith), and in a single rare silicate, arseiiiato, and vaiiadiate. Metallic liismuth fuses readilv, and gradually vohitilizes, depositing a (hirk yellow ring of oxide on the charcoal. The latter volatilizes in tho inner ilame without colouring tho flame-bor(h'r. Bismuth oxi«hi is at once reduced and volatilized on charcoal. Ft dis.solves in sodi um carbonate in an oxidating Hume, very readily, if a platinuni wire or other non- reducing support bo used. The glass is yeillow or yellowish-brown whilst hot, pahf yellow and opatpie when cold. In borax and ]ihos- phor-salt, it dissolves also readily. Tho bora.x glass in the O. K. is yellowish, hot ; and very pale yellow or white and opaline when cold. In the R. F. tla^ glass becomes clear from separation of tho reduced metal. The phosphor-.salt glass in the O. F may lie rend<'r(!d milk-whito by llaming or saturation. In the It. F., with tin, it is transparent whilst liot, and very dark-gray or black on cooling. In this respect, the reaction resembles that produced by antimony. Tiie presence of bismuth, in bodies -(>nerally, is detected by the dark-yellow coating or ring-deposit formed on charcoal by the fusion or ignition of the test-substance with sodium carbonate. This deposit is dis- tinguishetl from that formetl by lead, by its deeper colour and by im- parting no colour to the Hame. Also, l)y the black bead formed l»y it (or by another portion of tho test-substance) with phos|)hor-salt and tin in a reducing flame, as described above. The button of reduced bisimuth, moreover, is brittle ; that of lead, malleable. These nuitals may also be distinguished by the sublimates which they form when igniti'd on charcoal with iodide of potassium, according to the method of Merz ; or by fusion with a mixture of about equal parts of sidphur and iodide of potassium, according to the more delicate proce.ss of Von Kobell. With lead, the sublimate is lemon-ycillow, or in thin lay<'rs. greenish-yellow; whilst with bismuth it presents a vivid scarlet colour, or a ririg of this colour around the outer edge of a yellowish dtsposit. When a very small amount of bismuth oxide is associated with excess of lead oxide, Cornwall recommends a modidcation of the process, as follows : the substance, mixed with about an equal quantity of a mixture of five parts sulphur and one part iodide of {)OtHSsium, i.s. 42 BLOWPIPE PRACTICE. ignited in a test-tube by the spirit-fl.iiue or Bunseu burner. Tlie piesence of bisinutli is indicated by a scarlet or orange-coloured band, wliich forms above the yellow sublimate occasioned by the lead. (23) Lend — The occurrence of native lead is quite exceptional. The met.d occurs most commonly as a sulphide (galena), and not uiicomuionly as a sulphantimonite (and to some extent as a sulph- arsenito). Also, fre([uontly in an oxidized condition, as a sulphate, carbonate, phosphate and arseniate. Among rarer (natural) com- pounds, it occurs as a sclenide, telluride, chloride, oxide, chromate, vanadiate, tungstate, molybdate, antimoniate. The presence of lead in bodies gcmerally is made known in blowpipe testing by the two following charactei's : the formation of a yellow ring-deporsit on charcoal, and the ready formation of a malleable metallic globule — +hese reactions requiring, howevei", in some few cases, the assistance of sodium carbonate* or othei- reducing tlux for their pro[)er manifestation.* Lead oxide is immediately nnluced on -hareoal, colouiing the flame light-blue. It dissolves reaiUly in the blowpipe fluxes if the fusion Ije jjrcfonned on a non-reducing sup[)ort. Tiie glasses, produced by an oxidating flame, are colourless or yellowish, and become opaque by saturation or fl;'.ming. (See A]>pendix, No. O). (24) Thallmm — This new metal is present to the amount of over 17 per cent, in the rare selenido Crookesite, otherwise it is only known to occur (in very minute quantities) in certain examples of iron pyrites, copper pyrites, zinc blende, native sulphur, and some few other minerals. Its chief characteristic is its property of imparting a brilliant green coloration to the Bunsen or blowpipe flame. In other respects its reactions much resemble those of lead, but the oxidized riiig-de[)Osit (best been on a i)orcelain supjjort or on the surface of a boneash cupel) is lark brown. (See Appendix, No. 14). The thallium spectrum consists essentially of a single vivid green line near the position of the E. line of the solar spectrum. (25) Cadmium. — As an es.sential component, this metal occurs only in a rare sulphide, greenockite. It is pvesent, however, in small quantity in many examples of zinc blende, and in certain varieties of the carbonate and silicate of zinc. INIetallic cadmium, on charcoal before the blowpipe, shrinks s-omewlntt together, blackens, takes tire slightlv. and becomes volatilized in dense brown fumes. These • III the presence of giilphur, more esiwcially, the reduction is facilitiiteil by the addition of a (mall piece of iron wire, See note at foot of ynge 23. REACTIONS. 43 ner. The ^ ireJ baml, k lead. iccoptioiial. , and not s a sulph- sulpliate, mil) com- chromate, /| ice of lead ,i >y the two . f leposit oil glol)iile — assistance sir proper •liai'coal, B Itlowpipe )oi't. Tiie yellowisli, ix, No. G). lit of over ily known i)n pyrites, few other parti 11",' a In oth'.r 9 oxidized I'face of a 4). The freeu line ;al occurs ^ -, in small ^S varieties ^gm 1 charcoal ^H takes tire ^H H luUUtion of ^^^B deposit themselves in the form of a brownish-black and veddisli- brown coatinjj (CdO) with a tinge of brownish-yellow towards the outer edge. The deposit is at once reduced and dissipated by either flame, without communicating any colour to the flame border. In both the closed and open tul)e. if the latter be of narrow diameter, a metallic sul)limate is formeil near tli»^ assay-matter, ami a dark-brown sublimate, with yellowish edge, higher up the tube. Fused with j)hosplior-.salt on charcoal, metallic cadmium (like metallic zinc) yives rise as the bead cools to slight detonations and flashes of light. Cadmium oxide on ;i non-reducing support is infusii)le, and remains unvolatilized. With borax and phosphor-salt it forms colourless beads which become milk-white and opa(|ue by saturation or flaming. On ciiarcoal the oxide is rapidly reduced ami volatilized, l)ut yields no metallic globule. The dark red-brown sublimate, formed on char- coal or better on a ]>orceIain support by the fusion of a cadmiferous substance with sodium c.irlionate, is the princijial blowpipe-reaction of the metal. In the luesence of much zinc, the Idast must not be con- tinued too long, otherwise the dark deposit of cadmium oxide, formed before the deposition of the zinc oxide, may be obscured by the latter. For the detection of cadmium in the j)re.sence of zinc generally, see Ajipendix. No. 17. (•JCt) /^inc. — Of (ioui'tful occurrence in the native state. Found jirincipally as a sulphide, oxy-sulpliide, oxide, sulphate, carbonate, silicate and aluminate. Metallic zinc, when ignited on charcoal, burns vividly with transient flashes of gn'en, blue and greenish-white flame, and throws off dense fumes which become oxidized and deposited as a coating on the charcoal. This coating ZnO is jiale- yellow and phosphorescent when hot, and white when cold. It is not dri\en ofl' by the reducing tlame, unless the bla.st be long con- tinued. If moistened with a drop or two of nitrate of cobalt, and ignitt-d by ;i>. v,.;idating flame, it becomes of a light-green colour on cooling. Zinc oxide forms with borax and phosphor-salt colourless beads, which become milk-white and opatpie by .saturation or when flamed. ]Metallic ziu". fused with a bead of phosphor-salt on I'har- coal, detonates slightly and emits flashes of light afti'r removal from the flame — a reaction flist noticed by Wiihler, and comlidered to arise from the formation of a zinc phosphide.* It is manifested, however, ' I have trii'il, hut wiihoiit Micccs.i, fn makf this ri'iic^tioti iivuiliil)l(' for the (U'tcitioii of lihosiilmtfs liv fiisiiiif tlu-e. in juiwdtT. witli liomiMi- acid, Imrux iiiid otluT roiitfi'iits, and thon addin;; a piire of nulallic zinc (n tin- «!'>*"•■ The reaction, although HOiiit'timus prodiiccd liy tliis troatmunt, is too unciitain to sine us a test. 44 BLOWPIPE PKACTICE. not only by zinc but also by cadiniuni, aluiuinium and magnesium, and to some extent by iron pyrites, arsenical pyritoa and several other minerals ; but it is not produced by tin, lead or thallium. The presence of zinc, in bodies, is best detected by fusing the substance, in powder, with two or three parts of sodium carbonate iind a little borax on a clean j)iece of charcoal. A characteristic ring-deposit (lemon-yellow and phosphorescent, hot ; white, cold ; and green, on cooling, after ignition with cobalt solution) is readily obtained as a inile by this treatment. In the case of silicates (and indeed in all cases)the deposition of this ring-coating is facilitated by tirst fusing the test substance with 2)hosf)hor-salt, and then ciushing the saturated bead on the anvil, and re-melting it with sodium carbonate on charcoal. (27) I'm. — Native tin is of doubtful occurrence, The metal of commerce is obtained entirely from the binoxide, known in its natural occurrence as Cixssiterite or tinstone. Tin occurs also, but rarely, as a sul[)hide in tin pyrites; and the binoxide is present in small quantities in tantalates generally, and in certain titaniates, sili- cates and other compounds. Metallic tin melts easily, without colour- ing the i!ame. Before the outer flame it rapidly oxidizes and gives off slight fumes, which form a coating on the fused globule and on the charcoal immediately ai'ound the latter. The coating is slightly yellowish whilst hot, and white or greyish-white when cold, and it is not driven off by the flame, but in a long continued blast it may become reduced. When moistened with a drop of cobalt solution and ignited, it becomes on cooling blueish-green. SnO and Sn-'O^ (neither of any interest, mineralogioally) burn on ignition, and become converted into binoxide. The latter SnO-, is infusible l»y the blowpipe, but on charcoal, in a well-sustained blast, it is reduced to metal. The reduction is greatly facilitated by the addition of sodium carbonate, neutral potassium oxalate, or a mixtui'e of sodium carbonate and cj'anitlc! of potassium, the latter acting most rapiilly. In borax, the binoxide is very slowly attacked and dissolved ; and phosphor-salt acts upon it still more slowly. With both reagents the glass remains clear when flamed. With sodium carbonate in the outer flame, it forms, with effervescence, a grevish-white infusible mass. In a good reducing flame (especially if a little borax be added to promote fusibility) it yields leduced metal. As pointed out by REACTIONS. 46 aijnesmm, id several mm. The substance, nd a little ing-deposit green, on lined as a eed in all fusing the saturated bonate on : metal of \vn in its I also, but present in niatos, sili- out colour- d gives off md on the slightly 1, and it is ist it may solution md Su-0=' ition, and isible by is reduced ddition of of sodium 3t rapidly. Ived ; and agents the ite in the infusible c be added ed out by Berz<^liu«, a small ])ortion of borax should always lie added to the soiliuin carbonate in the examination of tantalates and infusible bodi&s, geuiirally, for the presence of .in. A malleable, easily oxidiz- al»le, metallic globule is then, as a rule, obtained without difficulty; but when a trace only, or very small percentage of tin is present, the regular reilucing proce.ss (explained on |)age 21) must be resorted to. A button of metallic tin may be distinguished by its malleability, feeble sul)limate and read}' oxidation, from other metallic globules as obtained by the blowpipe. In nitric acid it becomes converted into a white insoluble powder (SnO'-'), behaving in tliis respect like anti- mony ; but the latter metal gives a brittle button, and also a copious sublinuite or ring-deposit which volatilizes wholly or in chief part, aiul communicates to the flame a greenish coloration. Fiom silver, the tin globule is distingui.shed by its ready oxidation, and its con- vei'sion into in,solul)le binoxide by nitric acid — silver, in that reagent, dissolving rapidly. From lead and bismuth, it is distinguished also by this acid reaction, and by the non-formation on charcoal of a yellow sublimate. Wh(;n small pieces of tin and lead (or tin and thallium, or tin and bismuth), are melted together, a remarkable oxidation ensues. The fused ma.ss becomes rajiidly enciusted, and continues after withdrawal from the tiame, to push out e.xcrescences of wliite and yellow oxides. (See Appendix, No. 21.) IV. — FLUX-COLOURING MKTALS. The oxides of the metals of this group pos,sess, in common, the property of communicating distinct and more or less characteristic colours to borax and phosplior-.salt glasses belbi-e the blow-pipe. By some, also, a colour is imparted to the sodium bead; but most of these oxides are insoluble in sodium cai'l)onate. They fall into two leading sections, as in the following arrangement : — A. — Reducible from an oxidized or other condition hi/ the blowpipe. A*-. — Fusible, aud tlierefore obtaiued by reiUiction in metallic glol)ules : Copper. A'^ — Infusible (practically), and therefore obtained by reiluction in the form of separate grains or scales : t Magnetic : Nickel. Cobalt. Iron. tt Non-magnetic : Tuugsteuum. Molybdenum. B. — Ao< rediicibli' from an o.vidized or other condition /ii/ the tdowjn/ie. /i' — The borax-glass not rendered i opju(ue by Haming. I Manganese. Chronium. Vana- dium. B'^ — The borax-glass converted by i Haming inco a dark or light enamel : I Uranium. Cerium. Titanium. ■'■»i>»M 46 BLOWPIPE PRACnCET. I (28) Copper.-— This metal occurs frequently in the native state-. Also as a base in numerous sulpliides, .;ud in certain arsenides, selenides, sulpharsenites and sulphantimonites. In combination like- wise with chlorine. Also in an oxidized condition as Cu-0 and CuO; and in the latter form, as a base, very commonly in ai-seniates, phos- phates and cai'bonates ; and less commonly as a sulphate, chromate, vanadiate and silici-te. Metallic eopper, on cliarcoal, melts before the blowpipe into a malleable globule, the surface of whicl), if exposed to the outer flame, becomes quickly tarnished by a black coating of oxide. This oxide imparts to the flame-border a rich green colour. Cupreous sulphides, arsenides and related compounds become con- verted by careful roasting, with avoidance of fusion (see the Opera- tion, page 15), into the same black oxide; and a roasting of this kind is always necessaiy as a preliminary to the reduction of the cop- pei", and its detection by fusion with borax. Botii the red and black oxides fuse readily and becouie reduced on charcoal. With borax and phosphor-salt, the glass after exposure to an oxidating flame, is green whilst hot, and clear-blue when quite cold — unless much ix'on or nickel be present, in which case it retains its green colour on cooling. In a I'educing flame, especially on charcoal, the glass becomes almost colourless, and on cooling turns brick-red and opaque. This reaction (which serves for the detection of copper in the presence of most other flux-colouring bodies) is developed more easily with phosphor-salt than with borax ; but when very little copper oxide is present in the glass, it is not always obtained without long blowing, although the glass on cooling often becomes clear ruljy- i"ed. If however, a small piece of tin or iron-v ire be stuck through the soft glass, and the bead be then again submitted for a few moments to a reducing flame, the opaqxie red glass (due to the reduction of the CuO to Cu'-'O) is readily produced. In place of iron- wire, a small ft-agment of any substance containing FeO (as iron- vitriol, nuignetic iron ore, spathic iron, kc.,) ma}' be used to promote the reduction, the FeO becoming converted into Fe-'O' at the expense of some of the oxygen of the copper comi)Ound. The fusion may then be performed on platinum wire ; but, in any case, the bead must not be kept too long in the flame, as the whole of the copper oxide might bo reduced to metal, and the glass becomes colourless, by prolonged fusion. By this reaction, the presence of copper in bodies REACTIONS. 47 Live state-, arsenides, ation like- and CuO; ates, plios- clironiate, before the exposed to coating of len colour, come con- the Opera- nji of this of the cop- and black Tith borax ing flame, dess much een colour I the glass k-red and copper in aped more very little I without ear ruby- through or a few ue to the ce of iron- (as iron- ,0 promote 10 expense usioii may the bead the copper 3urless, by in bodies '4 generally (after the preliminary roasting of those which contain sulphur, antimony, ikc.) is unmiftakably revealed.* Another charac- teristic reaction is the bright azure-tlame produced by chloride of copper. The slightly-roasted substance may be moistened with a drop of hydrochloric acid — or fused with chloride of silver — and held just within the point of an oxidating flame. If copper be pre- sent, the flame around the test-stibstance will exhibit a brilliant azure coloration. The test mt>y also be made by simply fusing tlie substance on platinum wire with phosphor-salt, and then adtling some chloride of sodium to the bead. (8ee also, Appendix, No. 12). (29) Sickel — Occurs in small and variable proportions in most examples of meteoric iron, and also in some meteoric stones as a phosphide and sulphide. In minerals proper, it is found more especially as an araeiiide, antimonide, sulphide and sulpliarsenite; and very frequently it replaces a small [)ortion of the iron in pyrrhotite or magnetic pyrites ; it occurs also in an oxidized condition, at times as a simple oxide in coatings on nickel ore, but more commonly as an arseniate, carbonate, sulphate and silicate. In some (mostly mag- nesian) silicates, and in the apple-green variety of calcedony, known as chrysoprase, it is present in mnmte quantity as the colouring material of the substance. Metallic nickel is infusible in the blowpipe flame. As obtained by reduction of the oxide NiO by sodium car- bonate or other reducing agent on charcoal, it forms numerous minute particles of a shining white colour. These are strongly magnetic. 8ulphi(.les, arsenides and related compounds, become Miverted by roasting into this oxide. The latter is unaltered j^^^' *'c hy the blow- pipe flame. With borax, it forms in the O.F. a glass which is amethystine in colour whilst hot (if the NiO be in moderate quantity), and pure brown or yellowish-brown when cold. If not too deeply coloured, the glass on the addition of a carbonate or other salt of potassium in excess, is rendered more or less distinctly blue or greyisli- blue. The reaction, however, is not very strongl}' marke») will, t commonly e, a mineral y of its pro- flexibility, occurs also, r compound sd with leatl anhydride, ih-jireen and becomes gradually volatilized, fornung a deposit which is sliglitly yellowish whilst hot, and white wiien cold. When touched by tho reducing flame, this deposit a.ssume8 a dark-bluish tinge from partial conversion into Mo'-'O'. In addition to tho white coating, an indi.s. tinct reddish deposit is also formed near the test-matter. With sodium carbonate, reduction to minute steel-gray particles is easUy eflected on charcoal. On platinum wire, solution takes place with efTerve-scence. With borax, Itefore the O. F., a Yellowish glass, which becomes grey and opatpie l»y flaming, is formed ; and in the K. F., a brown or grey glass, with separation of dai'k flecks, the latter best sec^n by pressing tho bead flat before it cools. With phosjthor-salt, on cool- ing, and especially after exposure to a nulucing flamt;, a flue green glass results. By this reaction (combined with tho projMU'ty of colouring the flame pale yellowi.sh-green,* and yielding per se or with soilium carbonate a white sublimate and reduced particles of non-magnetic metal), molybdenum compounds are chiefly recognizit more proiiiinnntly by tho additiun of a little borax to the Hoda, as this promotes solution (see Appendix, No. 9) ; and it is also increased in intensity by melting a small portion of nitre into the bead, or by pressing the hot bead upon a small fragment of nitre. A greenish-blue bead of this kinn of ;i L|»i)eiulix, No. small portion iipuu a Binull ill! I is known sides dissolve in the ciiso of •y gi'P'it effer- fioni tli(* tost- i are stronj^ly ygen," ahove). lie pnjscnts ii test-niiitttn' l»f icing flume it cool slowly it ir is restored. I the blowpipo flame. When e formation of II fragment of m1 with borax, ;tle nningiineso re. The great brmation of a with sodium thousand may in of nitre, as ,e. Chromium ellowish-green n the pi'esence be fused with latter in the whilst in that , No. IG). w varieties of ire only in an jrmer state it ire common! V ^i in combiinition with iron in chromic iron ore, or. as a basi^ in certain silicates, and varieties of Hpinel. In many silicates it ih present as an inessential component, as in the emerald, proper. In the condition of Cr<)^ it occurs in coml»ination with lead oxide <«• copper oxide in the small group of chromates. Tiie leading hlowpijie reactions of chromic oxide are as follows: Per se, the oxide is practically un- changed. With sodium carbonate, it dissolves more or less readily, forming a yollowisii, opatjue bead in the outer flame, and a yellowish- green bead in a reducing flame. If a [tarticlo or two of nitre be fused into the bead, the latte*' becomes blood-reil whilst hot, and light-yellow when cold — a soluide alkidine chromate resulting. With borax and phosphoi-salt, clear, emerald-green glasses are produced, especially l>y treatment in a reducing flame, and after complete cooling. Whilst hot, the glass is yellowish or red, as in many other cases. The pro- duction of an enii raid green glass with liorax generally serves for the detection of chromium comiwunds ; but the character Itecomes neces- sarily masked to some extent by the presence of other flux colouring Itodies, as iron, co|»per, and cobalt oxides, for example. In the presenco of i)odies of this kind, chromium is best detected by fusing the test- matter (in powder) with three or four parts of sodium carl)onat() and a little nitre in a platinum spoon or loop of stout platimim-win;. A soluble alkaline chromate then results. The solution Hltereil or carefully decanted from the insoluble residuum may he divitled into two i)ortions. One portion may be evaporated to dryness, and the resulting deposit tested l)y fusion with borax. The other portion may be carefully neutralized by a drop or two of dilute nitric acid, or acetic acid, and tested with a fragment of nitralt; of silver : a red precipitate should be produced. Chroinates, also, when treated with sulphuric acid and alcohol, form a rich gnH'ii solution which remains green on dilution. Chromic acid, CrO'', per se, blackiuis Avhen igniteium in iron ores, tSrc, may also he detected l)y fusi; the test- matter, ?n tine jiowder, witli six or eight parts of potassium hisulithate (added in successive portions) in a |)laiitinun) spoon ; treating the fused mass with a very small quantity of warm water ; decanting or filtering from insoluble matter ; adding a few drops of nitric acid, and then five or six volumes of water ; and, finally, boiling for ton cr twelve minutes. Titanic acid, if present, is precipitated in the form of a white or pale-yellowish powder. This may be fused with pho3phor-salt, in a reducing fianie, for the production of the character- istic amethystine ghiss. As pointed out by Gustav Rose, a glass of this kind, rendered colorless or nearly so by the O. F,, and then slightly flamed, becomes opalescent from the precipitation of nunicrou.s crystals of TiO-. These are best examine'', in the flatteneil liend. by a microscope with object glass of moderate but not too low power. v. — ACHROIC METALS. This group is to a great extent conventional. Its representatives are separated from those of the preceding series by their property of forming imcoloured glasses with the blowpipe fluxes ; and from those of the next series by not imparting a colour ^.o the blowpipe-flame. Aluminum compounds, it nay be pointed out, are distinguished from those of the associated me(.als by not forr 'ug an opa(|ue gla.ss with borax, and by the blue colc;ur assumed after ignition with nitrates of cobalt. Compounds of t'.ie other metals belonging to the group, magnesium excepted, are of comparatively rare occurrence. (40) Alunminm. — O'jcurs in nature as a fluoride (in cryolite, &c.,) but essentially as au oxide, Al-'O''. The . .Iter com|)ound occurs alone and in a hydrated condition (corundum, diaspore, gibl«ite) ; and in combination with magnesia and other bases as the electi-o- negative principle of the small group of aluminates. It occurs also, and more frequently, as a base, in various silicates, j»hosphates, and sulphates. Exjeptioucally, also, as an arseniate ; and in combination with an organic acid in tiie mineral inoUite. Alumina presents the foUov mg blowpipe reactions: (I) Perse, it is infusible and unchanged. (2) Moistened with nitrate of cobalt, and ignited, it assumes, on coolinsr, a fine blue colour. The reaction is exhibited bv all ahiminouH silicates, phosphates, A'c, which are free from iron oxides or othei- ;icrongly coloured bcomes i>ale yellowish on ignition, but resumes its white colour on cooling, and remains infusilde. After treatment with cobalt-solution it becomes pale tlesh- red. With sodium carbonate it dissolves with etfervcscence, but is not reduced. With l»or;«x, it dissolves (easily, tim .saturated glass becoming opa({ue on cooling or by flaming. With phosphor-salt it forms a permanently clear bead. Its presence in minerals cannot We safely detected by tlie blowpipe alone. (42) Glucinum, or, Berijllium. — Occurs only in an oxitli/ed i on- dition, BeO, as a base in a small numl>er of silicates (Plieiiakite, Beryl, Euclase, ifec), and in a single aluminate (Chrysobcryl). (Jlucina is infusible f>er se, ..nd is not dissolved by sodium carlioiiate With cobalt sohition it becomes pale l)liiis!i-grey ; with borax and phosphor-salt it di.s,solves more or less rapidly, the saturated glass becoming opacpie on cooling or when flamed. When glucii\a is com- bined with other boilies, it.s blow|tipe reactions are not sutlicient for its detection. ' .Mi'tiillic uluiiiitiuni iiofti-ns at a Htroni; red-heat, Ihtoiiu-h sli(;litl.v tariiiiiheil unit lilititt'ri'(^cies of toleral>ly common occurrence. Zir- conia when ijnrnited. Lflows with more than onlijiary Itrit^htness, hut remains nnfuscMl. After treatment with col)alt solution, it assumes a dull violet tinhor-salt, foiininj^ a colourless i^lass which on saturation becomes opai|ue on coolinj; or by flamin<^. Zircon and other silicates in which zirconia is press, all of Lctions of a. It is solnhic in |ta(pi(! l»y s escapes and still nd, as an o in P(U-i- n various lates ami iuin car- cKoliiiii a, siuni car- si oxith's, olonr the n-1 turner, lissolves very reftdily, th»i saturated i;lass heeoniing opa(|uo on coolinji or when flanieil. Tlie non-color,ition of the (lame and the reaction with nitrate of C()l)alt ^^enerally serves to distiniiuish majinesian compounds, except in tlie case of certain silicates. In these, and in otlier doul)tful cases, the test substance, in fine powch'r, may Ix; dis.solved in a small (juaii- titv of liyv oxalic acid or oxalate of ammonium; and finally the magnesia is separated by souk,' t the above ,aiid various other) minerals, the distinctive lines come out very vividly by a sutliciently proloiit;ed if?nition of the substance per m: The small sharp-edt;ed fragment is conveniently helil in the platinum, tipped forcei)8, and these can be fixed at the projier height by thnisting their op|>OBite ends ocroMS the stem of one of the ordinary wire supports used in spectroscope examinations ; or they may be luiU8 i;ed ij^iiitiun I' )>lntinuin. |)08ite ends ins; or they )\wr hei;fht. 1 in i)ow