386 BRIDGMAN. 



considerations on thermo-electric action, it will be pointed out that 

 the data of this paper allow certain information to be gathered about 

 the behavior of various constants of thermionic emission under 

 pressure. The latent heat of vaporization of electrons, the density of 

 the electron atmosphere, and the Volta contact force between an 

 uncompressed and a compressed metal may be determined as a func- 

 tion of both pressure and temperature, except for an undetermined 

 function of pressure alone. 



Finally, it may not be too daring to say that it seems to me that 

 much of my previous work on high pressure effects at least suggests 

 a direction in which we may look for the explanation of these compli- 

 cated effects. The thermodynamic properties of liquids under high 

 pressures and all the mutual relations of the polymorphic forms of 

 solids have been found to be quite as complicated under pressure as 

 the thermo-electric properties above. I have shown in detail that 

 probably the properties of both liquids and solids are to be explained 

 in terms of the same agency, the effect of the characteristic shape of 

 the atoms, or, if one prefers to express it so, the nature of the field of 

 force surrounding the atom. It seems most probable that the elec- 

 trons in passing from atom to atom, or in playing about between the 

 atoms, may be subjected to forces changing in a complicated way as 

 the atoms are forced by pressure into positions of varying degrees of 

 adaptation to each others irregularities. 



The Jefferson Physical Laboratory, 

 Harvard University, Cambridge, Mass. 



