210 Profs. E. Rutherford and H. T. Barnes on the 
This increased for about three hours, when it reached a 
maximum. After reaching the minimum, the radium gra- 
dually recovered its heating effect, rising to its original value, 
Heaf Emissions in Grom Calories per Hour 
. : Ne) 
.e) = a a + 
098 
_09) 
S4NOLL 
Ove 

after about a month’s interval. At the same time the heating 
effect of the emanation-tube gradually diminished according 
to an exponential law with the time, falling to half value in 
about four days. | 

