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Differential magnetic susceptibility measurements on MnCl2·4H2O and CoCl2·6H2O have been used to map out complete H‐T phase diagrams for these two antiferromagnetic compounds down to T/TN≃0.15. The phase boundaries bordering the paramagnetic state near absolute zero with the external field along the preferred direction, as well as along perpendicular directions are well represented by the relation Hc=Hc(0) (1−C2T5/2−C3T7/2). It has been shown by Anderson and Callen that this phase boundary should reflect the temperature dependence of the spin‐wave renormalization. They find a dominate T3/2 dependence. Their argument is based on the fact that the two T3/2 terms which cancel in the Dyson ferromagnetic formalism, in fact add in this case, due to the repulsive interaction among antiferromagnetic spin‐waves. The data follow a predominately T5/2 dependence with a small T7/2 correction. No evidence for a T3/2 dependence is found. A further discussion of this point will be presented.

Certain inherent difficulties have been encountered in the large-scale manufacture of calamine lotion, U. S. P. XIV and in the preparation of phenolated calamine lotion N. F. IX. This report indicates that variations in the rate of settling of calamine and zinc oxide are due to variations in polyethylene glycol 400 monostearate from different sources and from different batches. A viscosity standard for the ester to correct this difficulty is suggested. The incororation of excessive air in the course of preparation and the resulting shrinkage ager packaging may be avoided by complete submersion of the stirrer and stirring at a slow speed. Increasing the polyethylene glycol 400 monostearate from 2 per cent to 4 per cent when phenol is to be added prevents loss of suspending power of the gel and the resulting separation that has frequently been experienced.

Experimental measurements have been made of the mutual diffusion coefficient of aqueous potassium hydroxide solutions over the concentration range from zero to saturated, using the diaphragm cell method of Stokes. Values are reported for three temperatures in the range 25–65°C. A simple activation theory of diffusion in concentrated electrolytes is presented, and is shown to describe satisfactorily the concentration dependence at each temperature. The behaviour of the mutual diffusion coefficient is compared with that of other transport coefficients of aqueous potassium hydroxide solutions, within the general framework of the activation theory.