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. 1903 Excerpt: ...has yet been deposited upon it, as would be the case if the current were allowed to pass after complete precipitation of the copper. As the copper must be tested for bismuth (see p. 648, 8, this volume), it must be preserved for a while. 3. Rinse the siphon and platinum spirals used in 2 with water into the large flask ...
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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. 1903 Excerpt: ...has yet been deposited upon it, as would be the case if the current were allowed to pass after complete precipitation of the copper. As the copper must be tested for bismuth (see p. 648, 8, this volume), it must be preserved for a while. 3. Rinse the siphon and platinum spirals used in 2 with water into the large flask, dissolve the slight quantities of lead dioxide adhering to the platinum spiral in hot hydrochloric acid over one and the same porcelain dish, evaporate to dryness with sulphuric acid the solution containing also a small quantity of platinic chloride, ignite the residue, dissolve the lead sulphate in hot hydrochloric acid, add ammonia to alkalinity, then nitric acid until just acid, precipitate with hydrogen sulphide, and reserve for the present the liquid with the precipitate, which we will designate as III. 4. The liquid in the large flask, and obtained in 2, boil, and then evaporate in a porcelain dish, at first on the water-bath; finally heat more strongly, until the free sulphuric acid is almost completely expelled, and but a few drops remain in the dish. When cold, add concentrated hydrochloric acid, warm, dilute, filter off from the small quantity of silicic acid derived from the vessels, saturate with hydrogen sulphide, and allow to stand for twentyfour hours at 75; repeat the saturation with the gas, and expel the excess by applying a gentle heat, in order to effect complete precipitation of the arsenic. Now filter through a suitable filter: a, the precipitate of lead sulphide, III (see 3); b, the precipitate of antimony sulphide, etc., II (see 1); and c (after previously removing the filtrates from III and II), the precipitate caused by hydrogen sulphide in the electrolyzed liquid. Wash the precipitate well, but do not dry it (term ...
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