282 Prof. H. E. Armstrong. Electrolytic [Mar. 25, 



decreases as the temperature falls, tlie coefficients of change being 

 practically very nearly the same in all cases, that the increase in 

 resistance as temperature rises is mainly due to the increase in mole- 

 cular inter-distances. As a rule, resistance increases on the passage of 

 a metal from the solid to the liquid state, but there are noteworthy 

 exceptions from which it would appear probable that even in pure 

 metals conductivity to some extent depends on molecular composition : 

 thus the conductivity of bismuth increases at the moment of fusion 

 from 0"43 to 0*73 of that of mercury at 21°, and that of antimony 

 from 0-59 to 0-84 (L. de la Rive, "Cornet, rend.," 1863, 57, p. 691) ; 

 it is well known that bismuth contracts considerably on fusion, and 

 this is probably also the case with antimony. Again, according to 

 Bouty and Cailletet (ibid., 1885, 100, p. 1188), the resistance of mer- 

 cury decreases at the point of solidification in the ratio 4*08 : 1 ; this 

 is a remarkable increase in conductivity, and it is difficult to believe 

 that it is wholly due to mere contraction of volume. 



That the behaviour of alloys is worthy of far more attention than 

 it has hitherto received appears most clearly from the few data at 

 disposal. As being the most instructive instance, I append the curve 



