A manual of qualitative analysis / by Robert Galloway.

  • Galloway, Robert, 1822-1896
Date:
1858
Catalogue details

Licence: Public Domain Mark

Credit: A manual of qualitative analysis / by Robert Galloway. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

    125/216 (page 113)
    bismuth, as the chlorides of these metals are decomposed by much water into soluble acid aud insoluble basic salts. This precipitate* may also arise from the presence of some substance insoluble in water, but soluble in the caustic, carbonated, or sulphuretted alka- lies, or in an alkaline cyanide—for example, phosphate of alumina, or alumina dissolved in caustic soda, sulpharsenious acid dissolved in carbonate of ammonia, tersulphide of antimony dissolved in an alkaline sulphide, cyanide of nickel dissolved in an alkaline cyanide; or the precipitate may be due to silicic acid, some alkaline silicate being present. If the precipitate is due either to antimony or bismuth, it will redissolve on the addition of a few drops more of hydrochloric acid. When silicic acid is the substance thrown down, the precipitate will appear very gelati- nous, and will remain uudissolved on the further addition of acid; a fresh portion of the original solution must therefore be acidu- lated with nitric acid, and evaporated to dryness to render the silicic acid insoluble; the ignited mass may then be digested with dilute nitric acid, and filtered.']' The analysis of the filtrate must then be conducted in the regular way, by adding to it hydro- chloric acid, &c. If the precipitate should be due to the presence of any of the other substances, a fresh portion of the original solution ought to be taken, and nitric acid added to it until it is decidedly acid. If the precipitate does not disappear on the addition of the acid, the solution ought to be warmed; if this should fail to dissolve the precipitate, it must be collected upon a filter, and examined as a substance insoluble in water and acids (see 551). The analysis of the solution or filtrate must then be conducted in the regular way, by adding to it hydrochloric acid, &c. * Hydrochloric .acid precipitates, of the inorganic acids, boracic acid; and of the organic acids, benzoic and uric acids. If the solution is very concen- trated, the two former are dissolved by hot water, and the uric acid by heat- ing with nitric acid. + The precipitate left upon the filter must be examined for silicic acid according to the method described under the head of that acid (see par. 405).