﻿344 



Mr. A. Fleck on the Condensation of 



usually started three or four minutes after the removal of 

 the tube from the pentane bath, and were extrapolated back 

 to the instant of withdrawal. Some convenient instant was 

 chosen, and by noting the interval of time between the time 

 of experiment and the chosen instant, and by assuming the 

 radium emanation to decay exponentially with a period of 

 average life of 5*55 days, the quantity obtained above by 

 extrapolation was multiplied by a factor to give the activity 

 that would have been obtained had the experiment been 

 carried out at the chosen instant. The effect of the decay of 

 the emanation was thus eliminated. After this correction 

 had been made the fraction of the emanation condensed is 

 obtained by substituting in expression (1). 



Results. — The curves obtained are shown in figure 4. 

 Curve A is for the weak tube, curve B is the first curve 

 for the strong tube, and curves C and D the second and 

 third curves respectively for the same tube. Dealing first 



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Radium emanation in exhausted straight tubes. 



with the curves obtained from the strong tube, it is observed 

 that each curve shows a marked maximum point at or near 

 — 161° C, and that as the concentration becomes less the 

 condensation curve is moved to the left. Thus curve D is 

 roughly parallel to curve B, but about 8° C. to the left. 



