R. W. Wood, Jr. — Effects of Pressure on Ice. 31 



tons, above which point it was difficult to force it, since the 

 ice melted rapidly, and the water oozed out around the piston 

 in spite of its perfect fit. On releasing the apparatus and 

 removing the piston, the bullets were found in the same posi- 

 tion ; they had not dropped to the bottom of the cavity as 

 they would have done had the mass been reduced to a liquid 

 state, thus proving that under a pressure of seven tons to the 

 inch (933 atmospheres) the ice had remained solid or viscous 

 to such an extent that it could easily support the lead. 



These same experiments were repeated under conditions of 

 greater cold : the blocks, after being filled with ice, were exposed 

 to a temperature of about —5° Centigrade until thoroughly 

 chilled, and were then carried to the press. This obviated the 

 difficulty of the rapid melting caused by the heat of the iron. 

 The results obtained, though practically the same, were more 

 marked than in the first experiments. The ice cylinders came 

 out with more violence than before, some fragments being pro- 

 jected to a height of ten or fifteen feet into the air. They 

 were of clear, transparent ice and several inches in length. 

 Small jets of water, in finely divided spray occasionally spurted 

 out around the ice cylinders as they rose from the tube ; this 

 spray congealed on falling back upon the block, showing that 

 the iron was below the freezing point. 



The experiment with the bullets was repeated with the 

 apparatus chilled below 0° C. A pressure of twenty-four tons 

 was reached before the index of the gauge stopped ; water 

 spurted out in a spray around the piston, and instantly froze 

 on the surface of the block as it ran down : ice, too, oozed out 

 in thin sheets. On removing the apparatus it was found that 

 the bullets had not dropped, showing that a pressure of twelve 

 tons to the inch was insufficient to reduce the ice to a liquid 

 state. One bullet which lay close to the wall of the cylinder 

 had been ground between the piston and the wall, and a por- 

 tion of it was spread out in a thin film over the iron. As a 

 final test, a piece of oiled leather was inserted between the 

 piston and the ice, which effectually prevented all leakage. 

 The index hand moved slowly along until it reached a point 

 indicating forty tons, when suddenly the air was filled with 

 fine jets of spray which spurted in all directions from the 

 block. The water had actually permeated the iron, forcing its 

 way through the pores of the metal or breaking minute paths 

 for its exit, and emerged in countless jets from the surface. 



This of course put a stop to further experiments, the limit 

 of resistance of the iron having been reached. A calculation 

 will show that in the last experiment the pressure was sufficient 

 to liquefy exactly one-fourth of the ice," being that produced 

 by a column of ice twenty miles high. 



