1432 
shaped portion, which is shorter than that of the vacuum glass. 
This copper tube is closed underneath (B,) by a metal stopper 
C. to which a tube C, of thin aluminium is attached (thickness 
0.3 mm.); this tube contains a sealed glass tube with the radium. 
The narrow space at the bottom of the vacuum glass in which 
this tube is placed, is cooled to a temperature that differs very 
little from that of the bath: the difference could hardly be 
established, when the copper vessel was filled with liquid air. This 
10e NTL 
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oy 
cs 
