In an appendix to a paper on the static diffusion of gases, communicated to the Society in 1900, it was shown that when a current of air containing a constant proportion of carbon dioxide is caused to move in a turbulent stream over the free surface of a solution of caustic alkali, the rate of absorption of that gas increases with the velocity of the air-current up to a certain optimal speed, beyond which no further increase in the speed of the current influences the rate of absorption. It was further shown that when the optimal velocity of the air-current has been reached, and the temperature is maintained practically constant, the rate of absorption then varies directly as the partial pressure of the carbon dioxide in the air. In other words, if under the above conditions the rate of absorption per unit of area of the liquid surface is
a
for a partial pressure of carbon dioxide represented by and is for a partial pressure of
p'
, then at similar temperatures,
a
/
p
=
a'
/
p'
. A suggestion was also made that this principle might be found applicable to a determination of the carbon dioxide in air, and that if the method were found to be a practical one it would have the manifest advantage of not requiring any measurement of the air from which the gas was absorbed.
On a new method for the determination of atmospheric carbon dioxide, based on the rate of its absorption by a free surface of a solution of caustic alkali
