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The longitudinal and transverse sound velocities for polyvinylchloride and polycarbonate with different molecular weights were measured at 30°C. The temperature dependence of the longitudinal sound velocity was measured up to 110°C. The longitudinal sound velocity decreased with increasing molecular weight, while the transverse sound velocity was nearly independent of the molecular weight. The longitudinal, shear and bulk moduli were obtained from the sound velocity and density data. Longitudinal and bulk moduli depended on the molecular weight strongly, but the shear modulus, Young's modulus and Poisson's ratio were insensitive to the molecular weight. The longitudinal sound velocity decreased with increasing temperature and the temperature dependence of the velocity changed drastically around the glass transition temperature.

Densities and ultrasonic propagating velocities of aqueous solutions of a series of nitroamminecobalt(III) complexes have been measured at 25 "C at concentrations less than 0.1 mol kg-l. Partial molar volumes, v2", have been determined by extrapolation of the relationship between 4, -Svm1f2 and m, where S, is the coefficient given by the Debye-Huckel (DH) theory. In this relationship, nearly horizontal slopes have been observed for all samples. Infinite-dilution values of partial molal compressibility, have been evaluated from the linear extrapolation of the empirical plot of 4b against "I2. The concentration dependence of 4b of these complexes is much higher than those observed for ordinary electrolytes of the same valency type. Values of vzo and 4bo assigned to the complex ions [Co(N02),,(NH3),,13-" increase regularly with the number of the ligand NO2-contained in the complex. Analysis of the observed variation of v2" and $bo of complex ions has shown that even for nonelectrolytic complex [CO(NO,)~(NH,),]~ electrostriction should occur in solution. Introduction About 15 years ago, using an ultrasonic interferometer and Ostwald-type pycnometer, we1v2 determined the compressibilities of aqueous solutions of such cobalt complexes as [CO(NH,),& (X = Cl-, Br-, or NO<), [Co(en),]C1, (en = ethylenediamine), and [ C~( d i e n )~] C l~ (dien = diethylenetriamine), etc., and calculated the hydration number of these complex salts. Recent development of

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The effects of the addition to organic acid baths for displacement solder plating of surfactants used as leveling agents and oxidation inhibitors used as bath stabilizers were investigated.The most effective surfactants were found to be isolated systems of Triton X-100 and laurylpyridinium chloride for the hydrophile-lipophile balance of the surfactants and a mixture of laurylamine and Triton X-100 for a decrease in foaming.o-Aminophenol and o-phenylenediamine, which are conjugated-system compounds of 1,2-substituted benzenes and have moderate reducing power, showed good properties as oxidation inhibitors.