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ROYAL SOCIETY OF CANADA 



Witli a pressure increasing 28 . 6 to 42 . kilograms per square cen- 

 timetre the piston moved from 0.000013 cm. per second after the first 

 four minutes, to 0.00717 cm. per second after four liours. The portion 

 of the ice forced out of the narrow orifice was found to be quite different 

 in structure to the ice inside the cylinder. The latter was clear and 

 homogeneous, while the expelled ice was cracked and broken into grains. 

 After long-continued pressure, however, the outflowing ice was as 

 compact and clear as that in the cylinder, which must indicate some 

 definite change in stnicture with time under the increased pressure. 



Similar to the experiments of Hess, and at about the same time 

 (1902), G. Tammann studied the velocity of flow of ice, during the 

 course of his experiments on the flow of crystalline substances. It was 

 clearly demonstrated that the plasticity of ice is relatively small, but that 

 near the melting-point it rapidly increases. Like Hess, he enclosed ice 

 in a steel cylinder with a small orifice at one end, out of which it was 

 made to flow under pressure. It was observed that, no matter what the 

 temperature, a constant slow increase in flow took place, with increasing 

 pressure, up to the pressure corresponding to the melting-point for the 

 particular temperature of the experiment, when a sudden rapid increase 

 in flow took place. 



He obtained the following results for different temperatures indi- 

 cated in the table: 



TABLE IX. 



The second column shows the pressure at which the rapid increase 

 of flow took place, and represents very nearly the pressure which would 

 be required to bring ice down to the melting-point corresponding to the 

 temperature of the experiment. The third column represents the 

 highest pressure of steady flow corresponding to the particular tem- 



