and Rocks under Pressure. 



245 



cases. The general nature of these results will be used 

 in this paper but the detailed solution is reserved for the 

 following- paper. 



This paper also contains measurements on the density 

 of several powdered minerals (quartz, feldspar, and talc) 

 after subjection to 30,000 kg/cm 2 . These measurements 

 were directly suggested by the experiments on collapse of 



Fig. 1. 



Fig. 2. 



Fig. 3. 



n 



LJ 



Fig. 1. Section of one form of specimen. 

 Fig. 2. Section of another form of specimen. 



Fig. 3. Cylinder mounted in rubber tube with brass end pieces, ready 

 for immersion in liquid and subjection to pressure. 



cavities, and should allow a more significant geological 

 interpretation to be attached to those results. 



Details of Experiment. 



The specimens were made in one of the two forms 

 showed in figs. 1 and 2. The two parts were cut from con- 

 tiguous parts of the same original crystal or rock. The 

 two flat surfaces on which the two parts abut were made 

 optically plane so that there should be as little distortion 

 as possible when the two parts were pressed together. 



