silver sulphate in water byproducts: AgI; Ag:Pt=1.28:0.65 molar ratio, Pt compd. added to a soln. of Ag salt, stirred overnight at 40°C in the dark, filtered, KCl (excess) added, stored for 24 h; ppt. centrifuged, washed (cold water, ethanol, diethyl ether), dried (vac.);