
218 RADIO-ACTIVE EMANATIONS [CH. 
the value of V; the amount of emanation formed in the compound 
during the interval ¢. 
In the experiment t= 105 minutes, 
and observed value 
Niet 
Nees 0131. 
Assuming that there is no decay during the interval, 
IN NOS Ss OO Seah. 
Thus Nei 480,000. 
Yo 
Making the small correction for the decay of activity during 
the interval 
mh = 477,000. 
%o 
We have previously shown that from the theory 
Mel 463,000. 
q@ » 
The agreement between theory and experiment is thus as close 
as could be expected from the nature of the experiments. This 
experiment proves conclusively that the rate of production of 
emanation in the solid compound is the same as in the solution. 
In the former case it is occluded, in the latter it escapes as fast as . 
it is produced. 
It is remarkable how little emanation, compared with the 
amount stored up in the compound, escapes from solid radium 
chloride in a dry atmosphere. One experiment showed that the 
emanating power in the dry solid state was less than $°/, of the 
emanating power of the solution. Since nearly 500,000 times as 
much emanation is stored up as is produced per second, this result 
showed that the amount of emanation which escaped per second was 
less than 107° of that occluded in the compound. 
If a solid radium chloride compound is kept in a moist atmo- 
sphere, the emanating power becomes comparable with the amount 
produced per second in the solution. In such a case, since the rate 
