VOLUME XXIV NUMBER 4 



THE 



JOURNAL OF GEOLOGY 



MAY-JUNE, iqi6 



NOTE ON THE LINEAR FORCE OF GROWING 

 CRYSTALS 



GEORGE F. BECKER and ARTHUR L. DAY 



Geophysical Laboratory, Carnegie Institution of Washington 



In 1905 we published a short paper, 1 qualitative in character, 

 with the purpose of demonstrating from simple laboratory measure- 

 ments the existence of a linear force, apart from the volume expan- 

 sion, exerted by growing crystals. We sought to show (1) that 

 when a crystal, fed with appropriate saturated solution, grows in 

 an open crack between walls with which it comes into contact on 

 both sides, pressure is exerted to separate the walls, notwithstand- 

 ing unrestricted opportunity for growth in other directions; (2) that 

 the linear force thus exerted is of the order of magnitude of the 

 breaking strength of the crystal and therefore a geologic force of 

 considerable magnitude and importance. 



The crucial experiment offered in support of this conclusion was 

 prepared in an ordinary crystallizing dish upon the bottom of which 

 was cemented a block of plate glass having a plane upper surface. 

 A well-formed crystal of alum was laid upon this plane surface, and 

 upon it a second plane glass plate carrying a weight. A saturated 

 solution of alum was poured into the crystallizing dish in sufficient 

 quantity to cover the crystal, and then left to evaporate quietly 

 under conditions reasonably free from temperature change and from 



1 "The Linear Force of Growing Crystals," Proc. Wash. Acad. ScL, VII (1905), 283. 

 Vol. XXIV, No. 4 313 



