Nucleation and growth in deposition of metals from vapor and oxidation of alloys: Measurement of the concentration of adsorbed Ag required for nucleation of Ag crystals to occur on a W substrate were made. The apparent critical concentration of adsorbate required to produce nucleation decreases with increasing impingent flux. The true critical concentration required to produce nucleation is the same for all fluxes and is 1.5 x 10 to the 14th power atoms/sq cm ec. Thermodynamic properties of solid Au-Ni alloys: Emf measurements were made on 10 Au-Ni alloys at temperatures of 775, 825, 900 and 935 C. The derived activities of both Ni and Au showed large positive deviations from Raoult's law. The enthalpies of mixing are positive, and both the free energy and entropy of mixing are positively in excess of ideal values at all compositions. Tabulations of the activities; free energies, entropies and enthalpies of mixing are given.