220 SCHEME FOR THE QUALITATIVE DETERMINATION OF 



being treated, the substauces must be careiully roasted. If test 1 fails 

 to show As, Sb, S, or Se, as sulphides, &c., the substance is either an oxide 

 or an alloy. If it is an oxide, the roasting, 2, is omitted. If it is an 

 alloy, it is subjected to the test 1, «, for Pb, &c., and then the test 2 A is 

 I)erformed by fusing it on coal with borax in the E. P., thus combining 

 2 A and 2 A « in one operation. Some sulphides during the roasting, 

 2 A, will become reduced to the metallic state, and then, after thorough 

 roasting, may be treated as alloys. A metal, or a raw sulphide, &c., 

 must never be treated on platinum wire, but the metal is fused on coal, 

 with a flux. This is done in E. F. if it is desired to get only non-redu- 

 cible metals in the flux, such as Fe, Co, &c. If Cu, Ni, and other re- 

 ducible metals are to be fluxed, it is performed in the O. F. The flux 

 so prepared is then transferred to the wire. Sulphides, etc., must always 

 be roasted before testing with borax, or S. Ph. 



The word head always refers to the flux, and button to the metal. In 

 regard to 2 ES, Sn and Zn are rarely found together, except in alloys. The 

 presence of the one generally implies the absence of the other. If 

 they are together as oxides, Su can, however, always be found in the 

 X)resence Zn by reducing them with soda and a little borax, and tritu- 

 rating the mass with water, p. 90.* In alloys the Zn can be detected by 

 treating for a short time in the E. F. ; the Zn, if present, will volatilize 

 first, and the coating may be tested with the cobalt solution. 



SCHEME. 



The substauce ma-y coutaiu As — §B> — S — Se — Fe — Mil — Cis — Co — Ni— Pb— 



Bi— Ay— Am— Mg:— Zn— C«l— Sbj— ca— Br— I-Co-— Si— N— EI, Ac. 



1. Treat on Ch. ia the O. F. to find volatile substances such as As— Sb^S— Se — 

 PB> — Bi — Cd., &c., p. Q>Q) et seq. Test in an open tube to see whethei" As, Sb, S, are 

 present as arsenides, &c., or in an oxidized state, j}. 63 et scq. 



a. If there are volatile substances present, form a coating, and test it with S. Ph. 

 and tin on Ch. for §b, p. 99, or to distinguish between PEj and Bb, p. 280. 



a. Yellow coat, yielding with S. Ph. a black bead ; disappearing with blue flame, no part of it yielding 

 greenish Sb flame. Pb and Hi. 



b. Yellow coat, generally with tvhite border, yielding black or gray bead with S. Ph, disappearing 

 with blue flame ; also the border disappearing with green liame ; PE> and Sb. 



c. Yellow coat, very similar to b, but yielding no blue flame ; Bi and Sb. 



d. Make a special test for Bi, p. .5-21. Pb in presence of Bi, if not in too small a quantity, is detected 

 by the blue flauie yielded by the coat, or by the reduced metal itself, p. 521. 



1). If there are no volatile substances present, divide a part of the substance into 

 three portions, and proceed as in A. 



2. If As— §1!> — S — Se are present, roast a large quantity thoroughly on Ch., p. 77. 

 Divide the substance into three portions, and proceed as in A. P. xv, note. 



A. TiJEAT.^iENT OF THE FlRST PORTION. — Dissolve a verv small quantity in borax 

 on platinum wire in the O. F., and observe the color produced. Various colors will be 

 formed by the combination of the oxides. Saturate the bead and shake it off into the 

 porcelain dish ; repeat this once or twice, p. 79. 



a. Treat these beads on Ch. with a small ijiece of lead, silver, or gold, in a strong 

 R. F.,p. 113. 



* These numbers refer to the pages of Plattner's Manual, translated by H. B. Cornwall, 2d edition. 

 D. Van Nostrand, New York, 1873. 



