﻿354 Mr. A. Fleck on the Condensation of 



emanation condensed, then E = N — Le~ 5 ^, since t = 5 hours. 

 When the experiment has been carried out for room and 

 liquid-air temperatures, the fraction of the emanation con- 

 densed is found by substituting the values of E T , E L , and 

 E R in the expression (1). The value of (c) cannot yet be 

 determined. 



A whole series of such determinations were made, and 

 then the tube was laid aside until no trace of the radium 

 emanation could be detected. A large number of deter- 

 minations as described above were then made for liquid-air 

 temperature alone, and the average value of the ratio 



M-Lg-°- 7 X 



was found. This was determined as 0'326. 



This factor was then used to multiply all values of 

 {N — he~ 5 ^} obtained during the experiments with the 

 mixed emanations, and for each temperature in that set of 

 experiments the value of 



0-326{N-I*r- 5 M + L£-°-^ 

 was subtracted from the corresponding value of M. The 

 result gives a measure of the radium emanation condensed 

 at a particular temperature at a certain time. The value so 

 obtained was corrected for the progressive decay of the 

 radium emanation as before to the value, G, which would 

 have been obtained had the experiment been carried out at 

 the chosen instant. The value of G is determined for room 

 and liquid-air temperatures and, as before, the fraction con- 

 densed is obtained by substituting G T , G L , and G E in the 

 expression (1). 



Example. — An example, for which the detailed curves 

 obtained are shown in fig. 10, will make the calculation 

 clearer. Curve A shows the curve obtained from the 

 measurements taken over the whole six hours during which 

 the experiment was carried out, while curve B is obtained 

 by plotting on a larger scale the measurements made imme- 

 diately after the exposure at the low temperature. This 

 latter curve was used to obtain the value of M. 



Temperature of experiment, —159 0, 5 C. 



Time of experiment, 1 day after chosen instant. 



Initial activity = 26*0 d.p.m. 



Irreducible activity = 4*8 d.p.m. 



.-. Value of L = 21*2 d.p.m. 



Activity after exposure = 80'5 d.p.m. 



.-.Value of M = 75*7 d.p.m. 



