TRANSACTIONS OF SECTION Bb, 679 
apparatus which has enabled us to determine the relative rates of diffusion through 
orifices in thin metal plates ranging down to 1 mm. in diameter. 
I have plotted the results of such a series of experiments (see fig. 2), showing 
the relative rates of diffusion of atmospheric carbon dioxide through equal areas of 
apertures between 20 mm. and 1 mm. in diameter, under constant conditions, and 
it will be noticed how very steep the curve becomes after diameters of 5 or 6 mm. 
are reached. 
The speed at which the diffusion of atmospheric carbon dioxide takes place 
Fig. 1. 
5 10 15 20 25 30 35 40 45 50 S5 60 G5 70 75 60 85 90 M7). 
~ 
through unit area of an orifice of 1 mm. in diameter is just sixteen times as fast as 
it is through unit area of an aperture of 20 mm.; and since we know that the rate 
of passage in the latter case is two and a half times greater than the alsorption 
rate of an equal area of a freely exposed surface of a solution of caustic alkali, we 
arrive at the conclusion that, under the particular conditions of our experiment, 
the diffusion rate through an aperture of 1 mm. is forty times greater than the 
tate of absorption of a free alkaline surface of equal area, 
