Hexachlor-platinates

Aqua regia dissolves platinum with ease, yielding the hexachlor-platinic add. This is mainly due to the chlorine liberated, since boiling hydrochloric add, like boiling nitric add, alone is without action on the metal. 

Although a solution of pure potassium hexachlor-platinate, K2PtCl6, is not reduced by boiling with potassium oxalate, reduction readily takes place if a trace of iridium in solution is added.3 In the presence of much iridium the reaction may even become violent. 

Salts of hexachlor-platinic acid may be conveniently divided into three groups, namely ... 

Pentachlor-hydroxy-platinic Acid, H2PtClB(OH).—The monohydrate of this acid, namely, H2PtCl5(0H).H20, is obtained1 as a deliquescent residue on keeping crystals of hexachlor-platinic acid in a vacuum over caustic potash at 100° C. for three days ... 

It readily dissolves in water, yielding a yellow solution with an acid reaction, sufficiently powerful to decompose carbonates.2 With ammonia no precipitate is obtained, which property serves to distinguish this acid from hexachlor-platinic acid. With ammonium chloride or potassium chloride the corresponding hexachlor-platinate is produced. 

Tetrachlor-dihydroxy -platinic Add, H2PtCl4(OH)2 or PtCl4.2H20, is obtained in solution by hydrolysing silver hexachlor-platinate with boiling water ... 

The solution is evaporated to dryness and the acid extracted with water, ammonium hexachlor-platinate remaining behind as an insoluble residue. 

Selenium dioxide, by oxidation of selenium by nitric acid, 119 purification, 120 Selenium hexafluoride, 121 Silica gel, platinized, use in preparation of hydrogen bromide, 152 Silicobromoform, 38 analysis of, 41 Silicoethane, hexachlor, 42 Silicoformic anhydride, 42 Silicomolybdic acid, 127 analysis, 128... 

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