A Comprehensive Treatise on Inorganic and Theoretical Chemistry

246 INORGANIC AND THEORETICAL. CHEMISTRY
an excess of potash-lye, there is formed a yellow liquid which dries to a scarlet
mass. When this product is heated not quite to redness, and the excess of potassium
hydroxide and chloride are washed out, there remains a rust-yellow, colloidal
platinate which is coagulated by the addition of a salt. It contains 7 per cent,
of potassium oxide ; hydrochloric acid, and hot sulphuric and nitric acids remove
the alkali ; cone, hydrochloric acid slowly converts it into potassium chloroplatinate,
and platinic chloride ; at a red-heat, the platinate passes into platinite
by the loss of oxygen ; it detonates violently when heated with combustible
matters.
M. Blondel dissolved freshly-precipitated, hydrated platinum dioxide in cone,
potash-lye, evaporated the decanted liquor over sulphuric acid, and dried the yellow
crust in air and then in vacuo. The composition agreed with that of potassium
platinate, K2PtO3.3H2O. When an acid is added to the aq. soln. of potassium
platinate it precipitates hydrated platinum dioxide. The soln. is stable when
concentrated and in the presence of an excess of alkali-lye. When dried at 110°,
potassium platinate passes into potassium hexahydroxyplatinate, K2Pt(OH)6.
I. Bcllucci and N. Parravano reported that the golden yellow crystals, obtained
by seeding the aq. soln. with the corresponding stannic salt, are trigonal, with
the axial ratio a : c=l : 1-9952, and