The silver-calcium system has been reinvestigated over the wholecornposition range by thermal analysis, X-ray diffraction, and metallography. A novel technique has been used to prepare and examine these reactive alloys. In the course of this project four intermetallic compounds have been observed for the first time; ~vliiie two others, viz., Ag,Ca and AgCa, which were reported before by others, have been confirmed. Three of the new co~npounds areTAg,Ca,, Ag,Ca,, and AgCa3, while the fourth was not isolated or examined in detail. Two other compounds which were described in earlier work as Ag,Ca and Ag,Ca, have been found to be Ag,Caz and Ag,Ca,, respectively. Major n~odifications have been made in the liquidus curve and possible reactions in the solid state are indicated.

Equivalent conductances of aqueous caesium chloride solutions have been measured in the range 0.1-3.5 N. These have been combined with literature values of transport numbers and diffusion coefficients to give Onsager transport and frictional coefficients in the concentration range 0.25-3.0N. The relative sizes of these coefficients are discussed in terms of solvation and water structure in a comparison with the other alkali chloride salts. The physical significance of the frictional coefficients is developed and the percentage of an applied force opposed by friction with other solution species is calculated. Abnormalities in caesium-chloride interactions are tentatively ascribed to ion association.

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Conductivity measurements are reported for magnesium sulphate in water, dioxan-water mixtures, and glycine solutions, and for lanthanum ferricyanide in glycine solutions. Dissociation constants have been derived, and it is shown that a simple electrostatic explanation will account for the variation of dissociation constant with dielectric constant. A comparison is drawn between ion-pair sizes as calculated by Stokes's law and by Bjerrum's method.NUMEROUS measurements have been made of the conductivities of salts in non-aqueous and in mixed solvents, and deviations from the limiting Onsager equation have in many cases been satisfactorily accounted for by the assumption of incomplete dissociation. Dissociation constants can be calculated, and in general i t would appear that when ion-pairs are formed from large spherical ions, or from large and stably solvated ions, variation of dissociation constant with dielectric constant may be accounted for satisfactorily by Bjerrum's treatment (Kgl. Danske V'idensk. Selskab., 1926, 7, No. 9). Very few measurements appear to have been made in media of dielectric constant higher than that of water, however, and for this reason the present work has been carried out. It has recently been shown by Monk (Trans. Furaduy SOC., 1950, 46, 645) that the conductivity of potassium chloride in aqueous glycine solutions is in agreement with the Onsager equation and i t appeared to be of interest to examine the behaviour of electrolytes of higher valency type in such solutions. Magnesium sulphate was chosen as a suitable 2-2-valency type salt, not subject to hydrolysis, and conductivity measurements have been made on solutions in water, and in dioxan-water and glycine-water mixtures. Measurements have also been made on glycine-water solutions of lanthanum ferricyanide, a 3-3-valency type salt, for which the conductivities in water and in mixed solvents of lower dielectric constant than water have been reported in earlier papers (Davies and James, Proc.Roy. SOC., 1948, A , 195, 116; James, J., 1950 James, J., , 1094). An exploratory study of conductivities in urea-water solutions was made, but drift in solvent resistance, presumably due to hydrolysis, w a s too great for accurate measurements to be obtained. EXPERIMENTAL.Glycine was dissolved, filtered, and recrystallised thrice from conductivity w:ter and finally dried to constant weight over potassium hydroxide in vacuo.grade) was purified by prolonged refluxing with sodium and fractional distillation (Kraus and Vingee, J . Amer. Chem. SOL, 1934, 56, 513). Magnesium sulphate (" AnalaR ") was recrystallised from water and dried over the partially dehydrated salt. Lanthanum ferricyanide, LaFe(CN) ,,5H,O, was prepared and analysed as described by Davies and James (Zoc. cit.). The conductivity equipment and experimental technique used have been described elsewhere (Davies, J., 1937, 432; James, Zoc. cit.). Concentrations were determined by weight, and volume concentrations were calculated from the densities of the mixed solvents, it being as...

Equivalent conductances of aqueous caesium chloride solutions have been measured in the range 0.01 -0.1 ON. These have been analysed by the methods of Fuoss and Guggenheim to obtain the degrees of dissociation and the association constant, K,. The agreement between the two theoretical treatments is excellent. The analysis of transport processes in an associated 1 : 1 electrolyte by irreversible thermodynamics is developed and compared with the stoicheiometric treatment. The true interionic friction for caesium chloride is calculated and compared with that for the completely dissociated alkali-metal halides. The correction reduces this interionic friction from its apparent value calculated on a stoicheiometric basis.