A Comprehensive Treatise on Inorganic and Theoretical Chemistry

PLATINUM 391
acid. The trigonal crystals have the axial ratio a : c=l : 1-87(X), and o.=72° 6' ;
the sp. gr. is 3-458; and the mol. vol. 302-3. H. Topsoe obtained zinc iodoplatinate,
ZnPtI6.9H2O, from a soln. of platinic and zinc iodides ; and by evaporating, over
sulphuric acid, a soln. of an excess of zinc iodide in hydrochloroplatinic acid. The
trigonal crystals resemble those of the magnesium and manganese salts ; the axial
ratio is a : c—1 : 1*8685, and a—72° 13' ; the sp. gr. is 3-689 ; and the mol. vol.
321-7. J. L». Lassaigne also prepared the deliquescent crystals and said that they
have an astringent taste. Vide supra, for platinic tetramminoiodomercurate,
[Pt(NH3)4j(HgI3)2.
H. Topsoe prepared manganese iodoplatinate, MnPtI6.9H2O, by evaporating
spontaneously, over sulphuric acid, a soln. of an excess of manganese iodide in
hydrochloroplatinic acid. The trigonal crystals have the axial ratio a : c —1 : 1-8685,
and