Abstract: "The general utility of vacuum evaporated films is discussed. The characteristics that makes this technique most useful are the uniformity of the films, the easy control of their thickness over a large range, and the adaptability of the system to different metals and compounds. The design of a vacuum evaporator should provide adequate pumping speed, cooling of components, filament heater supply, and general flexibility and adaptability of the components to different materials. The design of filaments or boats and the evaporation of Al, Ag, Au, Li, Na, UCl4, ThF4, Be, SiO, Nal (Tl), U, and UO2 are considered. Special attention is given to the problem of obtaining uniform layers of UO2 on a large, flat target relatively close to the source."

It has been found that two silver atoms replace one polonium ion during the electrochemical exchange of polonium ion with silver metal. It is believed that the most probable exchange reaction may be described by the equation Po++ + 2Ag = Po + 2Ag+ . From the concentrations of polonium ion and Ag+ ion when the exchange reactions were terminated, calculations indicate Po = Po^ + 2e", E°< - 0.7.