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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1883 edition. Excerpt: ...for some time. Z$ Iossibly also some IBI, if much alkaline phosphate was present. j If the filtrate from the ammonium sulphide ppt is dark coloured (probably indicating nickel), the solution should be acidieed with dilute HII, boiled, filtered, and again rendered alkaline with IH, before proceeding. EXPLANATION OF GENERAL TABLE. Hydrochloric acid precipitates silver, lead (in part) and mercury (mercurous) as chlorides, AgCl, PbCl8 and Hg, Cl, thus separating them from all the other common metals, whose chlorides are soluble. (Bismuth and Antimony as often precipitated here as oxychlorides BiOCl and SbOCl, but the ppt. at once dissolves in more HCl. Strong HCl precipitates barium salts, these being insoluble in strong acids. Cold water at once dissolves the ppt. These chlorides having been filtered off, Hydrosulphuric acid precipitates mercury (mercuric), lead, bismuth, copper, cadmium, arsenic, antimony and tin, as sulphides, HgS, PbS, Bi, S, CuS, CdS, As, Sb, S, or Sb, S5, SnS or SnS these being insoluble in dilute HCl. Arsenic compounds are first reduced to the arseniotw state with separation of sulphur, e.g. As, O, + 2H, S = As,0, + 2H,0 + S, . This operation is very slow, requiring continued boiling, and repeated saturations with H S, hence arsenic in this state is often overlooked. Some prefer to reduce the arsenic to the arsenious state by boiling with SO, before passing H, S, but this process is liable to lead to complications, such as precipitation of Ba, Pb, fec. as sulphates. A precipitate of sulphur on passing 11,8 indicates the presence of an "oxidizing" agent, such as free chlorine, hypochlorites, chromic arsenio or strong nitric acids, ferric salts, fec, e.g. H, S + Cl, = 2HCl + S. pptd. The ppt. produced by H, S is...
