On a Kinetic Theory of Solids. 31 



have examined this interesting circumstance (see " Changes 

 of Property of Amalgams by Repeated Fusion/'' Phil. Mag. 

 September 1890, p. 228). 



The mixtures of metals which produced the most sudden 

 increases of current in these experiments were those which 

 exhibited the most sudden liquefaction. An explanation I 

 venture to suggest of the increase of voltaic energy during 

 liquefaction is, that the molecules of the liquefied alloy are 

 usually in a state of more active motion than those of the solid 

 substance, partly because the liquid has absorbed more potential 

 heat ; and that the suddenness of the increase of the current 

 at the period of liquefaction is due to absorption of heat being 

 promoted, and chemical and voltaic action facilitated by the 

 sudden occurrence of convection currents in the liquid alloy. 



As energy is indestructible, the effect of each unit of heat 

 absorbed by the alloy upon its total amount of energy of 

 molecular motion must be the same whether the heat is 

 absorbed as specific heat and raises its temperature, or as 

 latent heat which, without altering its temperature, changes 

 its physical state by fusion, or its other properties, as in the 

 case of iron at its " critical point/'' 



The results of the experiments show that changes of voltaic 

 energy may be used in the above manner to detect physical 

 and chemical changes in metallic alloys. 



V. A Kinetic Theory of Solids, with an Experimental 

 Introduction. By William Suthekland *, 



THE present work started in an experimental inquiry 

 having a twofold object, — to try to ascertain whether 

 there is a general law connecting the elastic properties of metals 

 with temperature, as is the case with gases, and to discover it 

 if possible, and, failing that, to obtain empirical means of find- 

 ing the values of the elastic constants of the metals at absolute 

 zero, at which temperature they would be specially interesting, 

 as the molecules would be at rest. 



The first result was that a general law unfolded itself with 

 singular ease, namely that the law of variation of the rigidity 

 of the metals with temperature is the same for all : if n is the 

 rigidity at absolute temperature 0, and N that at absolute 

 zero, while T is the melting-point, then 



-=i-f-Y 



a law almost as simple as that of perfect gases. 

 * Communicated by the Author. 



