FREEZING AND MELTING. 



hands and squeeze it into water. Not being 

 strong enough, we must resort to mechanical 

 pressure, and by this means it has been done. 

 A, Fig. 27, is a strong metal cylinder, 

 screwed internally, and fitted with screwed 

 plugs B C and D E. F is a bullet, and the re- 

 mainder of the space C D is filled with water. 

 The apparatus is placed in a vertical position, 

 B beneath and E above, in such a freezing 

 mixture as that described in the last section. 

 The bullet, of course, lies at the bottom of the 



FlG. '27 TO MELT ICE BY SQUEEZING. 



water at the lower end, C, of the space F. When 

 the water is frozen, the bullet is at the bottom 

 of the ice, and will be found there if the 

 cylinder (kept the same end up) be taken from 

 the freezing mixture and the plug B be re- 

 moved. Then replace the plug, and turn the 

 cylinder the other end up, B above and E 

 beneath. 



Then by means of wrenches force in the 

 plugs very hard, so as to create great pressure 

 inside the cylinder, and keeping B as the upper 

 end, remove the plug E. 



121 



