The action of fluorine on _platinum_ has been studied with special
care. It is evident, in view of the corrosion of the positive platinum
terminal of the electrolysis apparatus, that nascent fluorine rapidly
attacks platinum at a temperature of -23 deg.. At 100 deg., however, fluorine
gas appears to be without action on platinum. At 500 deg.-600 deg. it is
attacked strongly, with formation of the tetrafluoride. PtF_{4}, and a
small quantity of the protofluoride, PtF_{2}. If the fluorine is
admixed with vapor of hydrofluoric acid, the reaction is much more
vigorous, as if a fluorhydrate of the tetrafluoride, perhaps
2HF.PtF_{4}, were formed. The tetrafluoride is generally found in the
form of deep-red fused masses, or small yellow crystals resembling
those of anhydrous platinum chloride. The salt is volatile and very
hygroscopic. Its behavior with water is peculiar. With a small
quantity of water a brownish yellow solution is formed, which,
however, in a very short time becomes warm and the fluoride
decomposes; platinic hydrate is precipitated, and free hydrofluoric
acid remains in solution.
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