MORAN] RADIUM EMANATION FROM WATER 63 
the rubber tubing attached to the flask. This changed the rate of 
flow causing the air to be forced out of the solution in irregular amounts 
which it was impossible to regulate without some form of automatic 
pressure-regulator. 
Experiments were also carried out with the temperature of the 
solution at 20° C., and at 30° C., and the number of divisions per 
minute obtained after deducting the natural leak is shown on the 
curve (No. 1.) 
By reference to the accompanying graph it will be seen that 
the value of the ionisation current for 100° C. can be extrapolated 
by producing the curve. The two probable points where the curve 
cuts the ordinate corresponding to 100° C. are A and B, the mean of 
which is at C, or the point 41-25. The intermediate values of the 
ionisation current can then be read off from the curve, and the frac- 
tional part of the emanation removed at any given temperature 
easily calculated. We thus find that by bubbling air through the 
solution at the rate of three bubbles per second, and for the size of 
tube used, the percentages of enamation removed for the temperatures 
below are— 
64-7% at 16-5° C. | 
82-9% at 60° C. 
66-7% at 30-0° C. 
95:07 at 804 
68-6% at 40-0° C. 
It thus appears quite evident that the temperature at which the 
amount of radium emanation in a solution is determined by the bub- 
bling-method is a very important factor, and should always be defi- 
nitely determined and kept constant during an experiment. The 
experiment also shows that at ordinary temperatures the error due 
to neglect of temperature considerations is not very serious, the effect 
of temperature being most marked between 30° C. and 100° C. 
Summary 
The object of this experiment was to study the release of radium 
emanation from water by bubbling air through the radium solution at 
different temperatures, at a definite rate of flow of air. Observations 
were made with the temperature of the solution at 16-5° C., 20°C., 
30° C., 60° C., and 80° C., and the results show that the release of the 
emanation is considerably increased as the temperature rises, naturally 
reaching an upper limit at 100° C. 
Sec. III, Sig. 2 
