An introduction to the study of chemistry / by Ira Remsen.

  • Ira Remsen
Date:
1890
Catalogue details

Licence: Public Domain Mark

Credit: An introduction to the study of chemistry / by Ira Remsen. Source: Wellcome Collection.

    390/410 (page 374)
    is precipitated by means of ammonium chloride, with which, as with potassium chloride (see p. 319), it forms a difficultly soluble compound, PtCl^ + 2NH^C1, or (NHJ^PtCIg. When this is heated to a sufficiently high temperature it is decomposed, leaving metallic platinum as a residue. By special methods the iridium can be sepa- rated from it. Platinum is a grayish-white metal, with a high lustre. Its specific gravity is 21.15, it being one of the heaviest substances known. The specific gravity of iron is 7.8, that of lead 11,4, and that of lithium 0.59. In other words, a piece of platinum weighs nearly three times as much as a piece of iron of the same dimensions, and nearly twice as much as a piece of lead of the same dimensions. Platinum is not dissolved by hydrochloric, nitric, or sul- phuric acid; but aqua regia dissolves it, forming platinum chloride, PtCl^. Pusing caustic alkalies attack it; sodium carbonate does not. It does not change in the air, and does not melt except in the flame of the oxyhydrogen blow- pipe. It resists the action of most substances. These properties make it extremely valuable to the chemist. Platinum crucibles and evaporating-dishes, foil, and wire are constantly used in the laboratory, and it is difficult to see how we could get along without them. Large retorts of platinum are used for the purpose of concentrating sulphuric acid and distilling it. Platinum chloride, PtCl^, is made by dissolving the metal in aqua regia and evaporating off the acids. It dissolves in water, forming a yellowish-red-colored solution, which is used in the laboratory for the purpose of precipitating po- tassium from its solutions, as the salt potassium cliloro- vlatinate^ K^PtCl^, or PtCl^ -|- 2KC1, is difficultly soluble