220 SCHEME FOR THE QUALITATIVE DETERMINATION OF 



being trojited, the substances must be carefully 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, r/, for Vh, &c., and then the test 2 A is 

 performed by fusing it on coal with borax in the K. F., thus combining 

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

 2 A, will becjome 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 (). F. The JJiix 

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

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



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

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

 l^resence of the one generally implies the absen(;e of the other. If 

 they are together as oxides, Sn can, however, alwiiys bo found in the 

 presence Zn by reducing them with soda and a little borax, and tritu- 

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

 treating for a short time in the li. F. ; the Zn, if [)resent, will volatilize 

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



S C II E M I'] . 

 The substiince may coutaiu As— Sa— S— Sc— Fc— ITiM— Cu— Co— Ni— Pb— 



55i— Ajf— Am— Mg— Zbb— Cd— Sbb— CI— Br-I-Co"— Si— N-li, &c. 



1. Ti-cat on Cli. in the O. F. to find volatile substances such as As— Sb— S— Se — 

 PB> — 9£l — C«l., «S:c., p. 66 et 8cq. Test in au open tube to see whether As, Sb, 8, are 

 present as ars(^nl(les, &c., or in an oxidized state, j). Go ct acq. 



a. If tliero arc volatile substances present, form a coating, and test it with S. Ph. 

 and tin on Ch. for SB), p. 99, or to distinguish between PE> and Bi, p. 280. 



a. Tcllow coat, yielding with S. Vh. a black bead ; disappcariiij; witli blue llanie, no part of it yielding 

 greenish Sb flame. IPb and Bi. 



h. Yellow coat, generally wilh white border, yielding black or gray bead with S. Th, disappearing 

 with blue flame ; also the border disappearing with green flame ; I»E> and 5^11>. 



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



d. Make a special test for Bi, p. 521. Pb in presence of Bi, if not in too small a quantity, is detected 

 by the blue flame yi(!ldod by the coat, or by the leducod mental itself, p. 021. 



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

 threw portions, and iiroceed as in A. 



2. It Ai9— SB* — S — S« are present, roast a large quantity thoroughly on Ch., \). 77. 

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



A. TitiCATMENT OF THK FiEST PORTION. — DissolvG a vcrv Small quantity in borax 

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

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

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



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

 R. F., p. 11:5. 



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

 D. Van Noatrand, New York, 1873. 



