434 Canadian Record of Science. 



When the deformation is carried ont at 400° C. no 

 trace of cataclastic structure is seen. 



An exj)eriment was then made in which the marble 

 was deformed at 300° C, but in the presence of 

 moisture, water being forced through the rock under 

 a pressure of 460 lbs. per square inch during the 

 deformation, which extended over a period of fiftv- 

 four days, or nearly two months. Under these 

 conditions the marble yielded in the same manner as 

 when deformed at 300° C, in the absence of 

 moisture, that is, by movements on gliding planes 

 and by twinning, but without cataclastic action. The 

 deformed marble, however, when tested in compres- 

 sion, was found actually to be slightly stronger than 

 a piece of the original marble of the same shape. The 

 structure developed was identical with that of the 

 marble deformed at 300° C. in the absence of water. 

 The presence of water, therefore, did not influence 

 the character of the deformation. It is quite possible, 

 however, that there may have been a deposition, of 

 infinitesimal amount, of calcium carbonate along very 

 minute cracks or fissures, which thus helped to main- 

 tain the strength of the rock. ^STo signs of such 

 deposition, however, were visible. 



By studying the marble deformed at a temperature 

 of 300° C, or better at 400° C, it will be seen that 

 structures induced in it by the movements, and the 

 nature of the motion, are precisely the same as those 

 observed in metals when they are deformed by impact 

 or by compression. In a recent paper by Messrs. 

 Ewing and Rosenhain, " Experiments in Micro- 

 metallurgy : Effects of Strain," which appeared in 

 these Proceedings, three photographs of the same 

 surface of soft iron, showing the results of progres- 



