PROCEEDINGS OF THE ACADEMY AND AFFILIATED 



SOCIETIES 



THE PHILOSOPHICAL SOCIETY OF WASHINGTON 



The 781st meeting was held on January 6, 1917, at the Cosmos Club. 

 Vice-President Sosman in the chair; 37 persons present. The minutes 

 of the 779th meeting were read in abstract and approved. 



Mr. E. Buckingham gave a paper on The effect of elastic strain on the 

 equilibrium temperature of a solid and its liquid. By methods not in- 

 volving any reference to the details of the theory of elasticity, a general 

 formula was deduced for the effect on the equilibrium temperature of 

 a solid and a liquid under a stress which produces a strain in the solid at 

 the surface of contact with the liquid. No restrictions Avere imposed 

 on the nature of the body or on that of the strain, except that the 

 strain must be non-dissipative. 



The general formula was applied to the case of linear compression, 

 and the result compared with some other formulas which have been 

 proposed. It agrees with Riecke's formula but does not agree with the 

 interpretation sometimes given to Poynting's formula. Comparison 

 with Bridgman's formula did not lead to any definite conclusion. 



Mr. E. D. Williamson gave a second paper on the same subject. 

 The particular case of an isotropic solid under the influence of a one- 

 sided thrust was treated. Formulas were deduced by methods similar 

 to those used by Gibbs for the change of the equilibrium temperature 

 on the face where the thrust was applied, and also at the free surface, 

 on the hypothesis in each case that a reversible equilibrium is possible. 

 At the free surface the change of temperature is always negative and 

 small, i.e. at such a surface the melting point is always lowered by a 

 small amount by any strain whatever. On the other hand at the sur- 

 face where the stress is applied the effect is very much greater and is 

 negative for a push but positive for a tension. The possibility of the 

 physical realization of this second case is in doubt. 



. The method can be extended to the case of solubility by the introduc- 

 tion of another variable — namely, the concentration of the solution. 

 The results are similar to those mentioned above, the solubilit} r being- 

 very slightly increased over the free surface but increased or decreased on 

 the stressed surface by a push or a tension, respectively, by a much 

 greater amount. 



Mi-. J. C. Hostetter then gave an illustrated communication on 

 The influence of non-uniform pressure on solubility. It is possible that 

 fluctuating temperature and, perhaps, some indirect effects brought 



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