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A method is described for determining the standard free energies of formation of the tantalum silicides from emf measurements on cells with solid thoria‐yttria electrolytes. Measurements were conducted over the temperature range 900°–1100°C in a purified argon atmosphere. Corrections for electronic conduction were established with Ta, Ta2O5 electrodes. Difficulties were encountered because the hard, refractory nature of the compounds prevented fabrication of dense electrodes and because silica films interfered with the measurements. At 1300°K, the measured standard free energies of formation in kcal per gram atom of silicon are: TaSi2 , −8.1 false(+1.8/−3.7false) ; Ta5Si3 , −24.0±3 ; Ta2normalSi , −27.2±3.1 ; Ta4.5normalSi , −37.3±7.2 .

The production at Los Alamos of the first electrolytic plutonium is described. Because it was scarce, it was initially prepared on a 50 mg scale. The electrolyte consisted of PuC13 dissolved in a ternary eutectic of BaC12-KCI-NaC1 and was operated at 660~ The technique involved the electrolysis of as little as 0.1 cm 3 of fused salt in a glass cell to produce liquid metal Subsequently, a few successful lg electrolyses were carried out with a maximum recovery of 75% of the plutonium content of the bath. It was found that the plutonium trichloride had to be dry and relatively low in oxygen and was, therefore, best prepared by dry methods. Electrolyses were performed under purified argon or hydrogen using tungsten or graphite anodes. The metallic product was pure and was used for early development of methods for cleaning, etching, and plating plutonium. Uranium was used for finding and testing techniques before plutonium became available. Acceptable deposits could not be obtained from UC14 dissolved in the ternary chloride eutectic, but were produced when UC13 was substituted for the tetrachloride. At about 650~ the uranium was deposited in the form of solid, dendritic crystals. These were, in general purer than the starting materials and were readily converted to mgssive metal.Plutonium metal is unique. It was created artificially for the express purpose of making a weapon of devastating power, yet it may also be used to breed additional fuel and produce useful power. Its compounds are extraordinarily poisonous. Although the melting 1 Present address: 414 Tracy Circle, Nokomis, Florida 33555. ABSTRACTA general linear expression is established depicting how surface fluctuations at an electrode due to microscopic metal deposition and dissolution at equilibrium state may develop with time after the beginning of electrodeposition. Applying the instability theory of electrochemical powder crystal formation, typical calculations were performed for diffusionlimited electrodeposition under nonsteady galvanostatic conditions. From the analysis, it is shown that only surface fluctuations with certain spatial modes survive to grow through the selection and filtration of random microscopic fluctuations by the electrode system. Surface forms calculated after a given deposition time, using both three-dimensional contour line plotting and cross-sectional profiles, were in agreement with experimental observations. In electrocrystallization, many random-shaped crystal grains are observed to form on the electrode surface. These grain morphologies may be generally * Electrochemical Society Active Member.

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In a bed of anthracite or bituminous coke fluidized by air at 10 to 15 meters per second at 1200 degrees to 1400 degrees C, molten ash forms beads on the surface of a coke particle, some exuding from its interior. The beads merge and detach them-selves to grow further as loose fluidized ash agglomerates of low carbon content.