170 THE FORMS OF WATER IN 



small surface, the liquefaction will of course be more 

 rapid, and this is what Mr. Bottomley has recently done 

 in an experiment of singular beauty and interest. Let 

 us support on blocks of wood the two ends of a bar of 

 ice 10 inches long, 4 inches deep, and 3 wide, and let us 

 loop over its middle a copper wire one-twentieth, or 

 even one-tenth, of an inch in thickness. Connecting 

 the two ends of the wire together, and suspending 

 from it 3, weight of 12 or 14 pounds, the whole pressure 

 of this weight is concentrated on the ice which sup - 

 ports the wire. What is the consequence ? The ice 

 underneath the wire liquefies ; the water of liq uefaction 

 escapes round he wire, but the moment it is relieved 

 from the press, xq it freezes, and round about tks wire, 

 even before it has entered the ice, you have a frozen 

 casing. The wire continues to sink in the ice; the 

 water incessantly escapes, freezing as it does so behind 

 the wire. In half an hour the weight falls ; the wire 

 has gone clean through the ice. You can plainly see 

 where it has passed, but the two severed pieces of ice 

 are so firmly frozen together that they will break else- 

 where as soon as along the surface of regelation. 



432. Another beautiful experiment bearing upon this 

 point has recently been made by M. Boussingault. He 

 filled a hollow steel cylinder with water and chilled it. 

 In passing to ice water, as you know, expands (§ 45) ; 

 in fact, room for expansion is a necessary condition of 

 solidification. But in the present case the strong steel 



