662 Blake — Solving Crystal Problems. 



follow from the application of some form of mathema- 

 tical analysis. For the present, the way is still open 

 to nse the means of investigation that have been 

 described in these articles. 



The unequal expansion of crystals in different direc- 

 tions by temperature changes will affect the crystal 

 angles, and complicate plans for attaining mathemati- 

 cal exactness, and this fact leads us to consider the pos- 

 sibilities of critical temperatures for various compounds 

 at which certain values will be reached. 



The whole problem of crystal growth has not yet 

 yielded to attempts at complete explanation, and if we 

 may judge by the past, it is probable that there will be a 

 constant supply of material for study that will keep up 

 the interest in crystals for an indefinite period. 



New Haven, Conn., 

 Sept., 1918. 



