BRIDGMAN. — MERCURY UNDER PRESSURE. 437 



uons passage from the " molekular ungeordnet " assemblage of the 

 liquid to the regular arrangement of the crystal on a space framework 

 may be accomplished. We may think of the molecules as cubes, for 

 example, with intense centers of force at the corners. As the mole- 

 cules wander past each other in the liquid state, there will be a 

 tendency for them to linger with the edges or the faces in contact. If 

 the time during which they so linger in symmetrical positions with 

 respect to each other becomes appreciable with respect to the total 

 time, we will have some approach to the properties of a crystal, the 

 approach becoming closer as the time of contact becomes relatively 

 greater. And entirely aside from the question of molecular structure, 

 there seems no difficulty in conceiving that if the temperature and 

 pressure are varied properly on a cubical crystal, for example, that 

 the three elastic constants might so change with respect to each 

 other that two of them should eventually become equal, giving the two 

 distinctive constants of an isotropic body, and so continuous passage 

 from a crystalline to an amorphous body. 



Summary of Results. 



Data have been collected in this paper sufficient to give the p-v-t 

 surface of the liquid, and the location and magnitude of the dis- 

 continuity in this surface when the liquid freezes to the solid over a 

 pressure range of 12,000 kgrn-Zcm.*^, and a temperature range from 

 — 38°.85 to +20°. Tables of various quantities of thermodynamic in- 

 terest are given for the liquid; such as the compressibility, the dilata- 

 tion, the change in the specific heats, the adiabatic compressibility, 

 the heat of compression, and the change in internal energy both along 

 an isothermal and along an adiabatic. For the change liquid-solid 

 the co-ordinates of the melting curve are given, the change of volume, 

 and the latent heat. The results do not show any behavior in the 

 liquid at high pressures opposite in character from that which would 

 be predicted from their trend at lower pressures. But for the change 

 solid-liquid, it seems that at high pressures there is a change in the 

 trend of the latent heat which invalidates Tammann's argument for 

 the existence of a maximum. If either a maximum or a critical point 

 exist for the transition solid-liquid it is at pressures higher than are at 

 present open to direct realization. Such a point could not well exist 

 at less than 50,000 kgrn-ycm.*^. 



Apart from the main work of the paper a number of other quantities 

 relating to mercury have been determined, some of them very roughly, 

 either by a direct calculation from the new data given here, or else by 



