No abstract

A critical evaluation of the mean activity and osmotic coefficients in aqueous solutions of the alkaline earth metal halides at 298.15 K is presented. Osmotic coefficients were calculated from direct vapor pressure measurements, from isopiestic measurements, and from freezing point depression measurements. Activity coefficients were calculated from electromotive force measurements on galvanic cells, both with and without transference, and from diffusion data. Given are empirical coefficients for three different correlating equations, obtained by a weighted least squares fit of the experimental data, and tables consisting of the activity coefficients of the halides, the• osmotic coefficients and activity of watP.T, ann thp. p.xr.P."" C.ihh" energy of the solution as a function of the molality for each electrolyte system. The literature coverage is through September 1976.

19. Dr. Weidlein has been prominently and actively identified with the Institute for over 40 years, serving as a senior fellow 1912-t6, and then as an executive staff member from 1916 to 1951, when he was made President. He is noted internationally as a scientist, research administrator, and author. Following his retirement he will spend several months in Europe on a Federal Government mission. Dr. Weidlein will continue to serve the Institute as a member of the Board of Trustees and will be available in an advisory capacity in the administration of research programs.ALBERT H. COOPER has joined the American Hard Rubber Co., New York City, as assistant to W. M. Bergin, Director of Research & Development. A well-known authority on organic and inorganic chemicals, Dr. Cooper will devote the major part of his time to furthering American's accelerated chemical research and allied production programs. He is the owner and manager of Pilot Engineering Co., industrial consultants on plant design and production problems; he also is head of the Dept. of Chemical Engineering at Pratt Institute in Brooklyn. J. J. LANDER has resigned as chemist with the Naval Research Lab., Washington, D. C., to assume the position of Director of Research of the Storage Battery Division, Electric Auto-Lite Co., Toledo, Ohio. J. S. DEWAR recently was promoted to President of National Carbon Co. Ltd., Toronto, Ont., Canada. He has the distinction of being the youngest chief executive in the history of the company.

Vol. 71 V. Summary 1. The distribution of hexadecylpyridonium chloride between water and nitrobenzene a t 25' has been determined. The simple ion activity product in water divided by the simple ion activity product in nitrobenzene is 9.00 X 2. The conductance of hexadecylpyridonium chloride in water, water saturated with nitrobenzene, nitrobenzene and nitrobenzene saturated with water, has been determined a t 25'.In water saturated with nitrobenzene, the breakpoint in A comes a t 5.7 to 5.8 X In pure water, A passes through a slight maximum starting approximately a t 6.7 XThe ion pair dissociation constant in nitrobenzene has been evaluated by the Fuoss method. 4.water, while in pure nitrobenzene, k is only about one-half that, namely, 4.26 XThe calculated sample ion activity ratio is constant a t concentrations less than 5.8 X but increases a t higher concentrations. This indicates that a t concentrations less than critical, the salt is completely dissociated in the water phase. The value of the critical concentration determined in this way is in good agreement with that determined from the A -d C plot.An estimate has been made of the simple ion concentration product a t concentrations greater than critical. An attempt has been made to calculate the state of the system on the assumption that only one complex species exists a t concentrations greater than critical. PROVIDENCE, R. I. RECEIVED SEPTEMBER 1 8 , 1948 5. 6.In a reCent article,' we described in detail an apparatus and technique for the determination of the diffusion coefficients of electrolytes by means of conductance measurements. Values of the diffusion coefficient of potassium chloride a t concentrations from 0.001 to 0.01 N a t 25' were reported. The results a t 25' have been extended to higher concentrations2 and determinations in the dilute concentration range have also been made a t 20 and 30". The present communication contains the new results and a summary of all the results with emphasis on their theoretical computation.

A critical evaluation of the mean activity, Y~" and osmotic coefficients, cj>. of aqueous calcium. chloride at 298.15 K is presented for the concentration range of 0 to 10 mol• kif!. Osmotic coefficients were calculated from direct vapor pressure measurements, from isopiestic measurements or from freezing point depression measurements. Activity coefficients were calculated from electromotive force measurements of galvanic cells. both without liquid'i.unction and with transference, and from diffusion data. A non-linear least-squares program was used to fit data from all sO\lrces using both + and In y* as a function of molality. An eight-parameter .extended Debye-Huckel equation describes the osmotic coefficient, the mean activity coefficient, and the excess free energy as :II. function of molality. The scientific literature has been covered through July, 1976.