352 MINERAL RESOURCES, 1914----PART I.
tion, potassium platinic chloride (K2PtCl6), a yellow crystalline precipitate is formed when potassium chloride (KCl) is added; or ammonium platinic chloride (NH4)2PtCl6, also yellow, when ammonium chloride (NH4C1)
is added. Both these precipitates are insoluble in alcohol but are
soluble in water, and may be reduced by heating, so that sponge
platinum is left.
Iridosmine
flakes are distinguished from platinum by their brittle-ness and by
their giving off a pungent, unpleasant odor if highly heated. This odor
is caused by the decomposition of osmium. The flakes will scratch
glass, but can be scratched by quartz.
