The coefficient of diffusion K of the emanation into the liquid can be obtained from the same equation used to determine the diffusion of the thorium emanation into air,
where λ is the constant of decay of activity of the radium emanation and x the depth of the layer of water from the surface.
Putting
it was found that
for water α = 1·6,
for toluol α = ·75.
The value of λ expressed in terms of a day as the unit of time is about ·17.
Thus the value of K for the diffusion of the radium emanation into water = ·066 cm.2 / day.