150 SIR ESONGAWILID) JH, JOVAIE SZ. 
monocarbonate and fluid biproduct. The introduction of capil- 
larity to explain the existence of differential pressures in the 
rock-mass cannot be regarded as other than hypothetical. It is 
hoped that the suggestion may lead to fruitful experimentation ; 
for it is doubtless to the experimental geologist and to the 
physical chemist that we must finally appeal in determining the 
source of mechanical energy in deep-seated chemical reactions. 
The hypothesis should, of course, also be tested by reference to 
the conditions at other localities where deformation in sedi- 
mentary rocks has been produced during the growth of concre- 
tions, whether composed of calcite or of other material. 
REGINALD A. DALY. 
