Adams c& Colter— The Flow of Marble. 473 



The casting is so arranged that hot gases circulate in an 

 annular channel (D). within it, and outside of the wrought 

 iron cylinder (A), the rock (B) being thus kept at a high 

 temperature while the pressure is applied. The casting is as 

 massive as possible and a very uniform temperature is thus 

 maintained during the whole time of the experiment. The 

 temperature of the enclosed rock is ascertained by means of a 

 platinum — platinum rhodium couple (C), provided with prop- 

 erly calibrated resistance boxes, etc. This lies in the air space 

 (E) by the side of the tube which incloses the specimen. The 

 hot gases are excluded from this space by the wall (F). The 

 whole is well lagged with asbestos, asbestos millboards (H) 

 being also inserted between the bases of the pistons and the 

 plates of the press. 



When it is desired to deform the rock at high pressures and 

 temperatures in the presence of water, a modified form of the 

 stove was adopted. The apparatus employed for the purpose 

 has been described in the former paper, to which reference 

 has been made. 



Upon the conclusion of the experiment the deformed tube 

 with its enclosed rock was placed in a lathe and the steel tube 

 was carefully turned off until a mere film of metal remained. 

 This was carefully filed through along one line and the enclosed 

 rock was thus obtained intact. 



In experiments where very accurate measurement of the pres- 

 sures employed was required, the large 100-ton Wickstead test- 

 ing machine set up in the testing laboratory in the Engineering 

 Building of McGrill University was employed. In other exper- 

 iments a series of three hydraulic presses, provided with suit- 

 able intensifiers and necessary accessory appliances, were 

 employed. These were calibrated from time to time by direct 

 comparison with the Emery testing machine in the testing lab- 

 oratory, and the accuracy of their reading thus maintained. 

 The most powerful of these presses, which was the one usually 

 employed, has a capacity of 120 tons. 



The Flow of Marble. 



In a former paper, as has been mentioned, it has been shown 

 that under conditions of differential pressure marble flows as a 

 plastic body. In the present contribution the results of fur- 

 ther experimental work, carried out with the view of obtaining 

 a more complete and thorough knowledge of the behavior of 

 marble under varying conditions of differential pressure, are 

 presented. 



