834 Chemical Significance of Crystal Structure. [April 15, 



abundantly confirmed by numerous series of determinations in addi- 

 tion to that now quoted. It is thus definitely proved that the law 

 of valency volumes, first enunciated on the ground of the crystallo- 

 graphic evidence, holds rigidly in the case of these liquid substances. 

 Suificient has been said to demonstrate that a method has now 

 been devised by means of which the vast stores of accurate gonio- 

 metric measurements collected by crystallographers during the past 

 century can be interpreted and that the requisite interpretation has 

 in many cases already been given. Professor Liveing, in a discourse 

 delivered in this room nineteen years ago, suggested that crystalHne 

 forms are the outcome of the accepted principles of mechanics ; the 

 aid of these, and of these alone, has been invoked to show that crys- 

 talline structures result from the equilibrium of the attractive and 

 repulsive forces radiating from the atomic centres. 



[W. J. P.] 



