Heating Effect of the Radium Emanation. 213 
for the emanation-tube, when the emanation is removed from 
it. The emanation was allowed to stand four or five hours 
in the emanation-tube, so that the excited activity on the 
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walls of the tube had reached a practical maximum. The 
ends of the tube were then broken, and the emanation rapidly 
withdrawn. The heating effect of this tube was then deter- 

