PROFESSOR GRAHAM ON THE DIFFUSION OF LIQUIDS. 
3 
The surface attraction of molecules assumed will recall the surface attraction of 
liquids, which is found necessary to account for the elevation of liquids in tubes and 
other phenomena of capillary attraction. 
(1.) An early preliminary experiment was made upon the liquid diffusion of a body, 
with whose diffusion as a gas we are already well acquainted, namely, carbonic acid 
dissolved in water. 
Two half-pound stoppered glass bottles were selected, of which the mouths were 
1’2 inch in diameter, and the lips were ground flat so as to close tight when applied 
together (fig. 1). One of them, placed firmly in an upright Fig- i- 
position, was filled to the base of the neck with carbonic acid 
water. Over this distilled water was poured, care being taken 
to disturb the liquid below as little as possible, in filling up 
the neck. The second bottle, filled with distilled water and 
inverted upon a glass plate, was slipped over the first at the 
water-trough. The solution of carbonic acid in the lower 
bottle was thus placed in free communication by an aperture 
of T2 inch, with an equal volume of pure water in the upper 
bottle. It was expected that the carbonic acid would be 
found, in time, equally diffused through both bottles. 
After forty-eight hours, the upper inverted bottle was again slipped off from the 
lower one, upon a glass plate, and the ratio of the gas found in the upper to that in 
the lower bottle determined by the weight of carbonate of baryta which the liquids 
of the two bottles afforded respectively. It was as 1T8 to 12*80 (about 1 to 11), 
instead of the ratio of equality, which would undoubtedly be the ultimate result of 
diffusion, were sufficient time allowed. 
After five days, in a second experiment with a weaker solution of carbonic acid, 
the gas was found to be distributed — 
In upper bottle . . . . T63 
In lower bottle .... 8*44 
or in the proportion of 1 to 5 nearly. 
In other experiments where the liquid in the upper bottle was a solution in water 
of nitrous oxide gas, instead of pure water, the carbonic acid of the lower bottle was 
also observed to diffuse into the liquid above it, as freely as it did into pure water in 
a comparative experiment; the ultimate ratios being 1 to 0*12 in the nitrous oxide 
liquid, and 1 to 0*10 in the water experiment. 
With the necks of the pair of bottles occupied by sponge charged with distilled 
water, the diffusion of the carbonic acid of the lower bottle proceeded with little 
friend Mr. T. S. Thomson of Clitheroe. A decided preference was given by Mr. Thomson, and also by the 
late Mr. Ivory, to the last, or the attraction theory of diffusion, over that of gases being vacua to each other. 
See Phil. Mag., 3rd series, vol. xxv. pp. 51, 282. 
