102 TRANSACTIONS OF THE 
moisture content per unit volume is p and t is the time. 
Substituting for v the value given, we obtain finally :— 
dp —.— ed dp awe 
dt da \gn a 
Assuming equilibrium, we may equate the right 
hand member to zero and the finite equation thus obtained 
is given as follows :— 
p =(ax +3)? 
where a and b are integration constants. It will be 
observed that the surface tension, viscosity, and radius of 
particle disappear from the “equilibrium” equation. 
This equation is parabolic in character and a negative 
value of the coefficient @ will give values consistent with 
experimental data at present available (including in par- 
ticular that presented by Dr. Widtsoe in Utah Station 
Bulletin 115). 
We are conducting some laboratory work and hope 
to furnish an empirical solution which will be reported 
later. 
