SOME POSSIBLE ROLES OF CATHODIC FILMING IN THE ELECTRODEPOSITION OF ALLOYS .2.

A study was made of the postulate that electrodeposited binary alloys with fixed whole number atomic ratios similar to the 1:1 nickel-tin al loy could be deposited by reduction of an insoluble film containing th e two metals in a fixed atomic ratio. This investigation involved the study of two systems that, during reduction, precipitate insoluble com pounds that contain two reducible metal ions. The thallium-chromate sy stem was shown to precipitate thallium(I) chromate and thallium(I) dic hromate. Both of the insoluble compounds were shown to be reducible fr om aqueous pastes and the product of the reductions was an alloy with a 1:2 atomic ratio of thallium to chromium. The second binary system s tudied was the copper(I) or (II)- ferro and ferricyanide system. Elect rodeposition from pastes or solutions produced a copper-rich deposit, in which its composition varied with solution composition. The insolub le flim did interfere, however, with hydrogen evolution, causing highe r current efficiencies.