JO STEPHEN TABER 
enlargement of certain crystals at the expense of others does not, 
however, continue indefinitely. 
NATURE OF FORCES THAT SEPARATED THE VEIN WALLS 
It has been demonstrated that under suitable conditions crystal 
growth is accompanied by the development of a force which may 
even exceed the crushing strength of the crystals. The nature of 
Fic. 6.—Chert nodule containing calcite veinlets which do not pass into the 
inclosing limestone. Two-thirds natural size. 
this force has been discussed in several recent papers. Bruhns 
and Mecklenburg ascribe the pressure effects accompanying crystal 
growth to the “‘forces of adsorption and capillarity.”* This has been 
refuted by Becker and Day and independently by the present writer. 
Becker and Day published a paper “with the purpose of demon- 
strating .... the existence of a linear force, apart from the volume 
expansion, exerted by growing crystals.’”’ They conclude (1) that 
<W. Bruhns and Werner Mecklenburg, ‘‘Uber die sogenannte ‘Kristallisations- 
kraft,’”’ Jahresbericht der Niedersdchsischen geologischen Vereins zu Hanover, VI (1913), 
106-8. 
