Prof. Graham on the Diffusion of Liquids. 183 



The surface attraction of molecules assumed will recall the 

 surface attraction of liquids, which is found necessary to ac- 

 count for the elevation of liquids in tubes and other pheno- 

 mena 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 position, was filled lo 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 communica- 

 tion by an aperture of 1 *2 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 

 1*18 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 solu- 

 tion of carbonic acid, the gas was found to be distributed — 

 In upper bottle . . . 1*63 

 In lower bottle .... 8*44? 

 or in the proportion of 1 to 5 nearly. 



the law of diffusion which had been drawn from observation, by my late 

 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 attrac- 

 tion theory of diffusion, over that of gases being vacua to each other. See 

 Phil. Mag., 3rd series, vol. xxv. pp. 51, 282. 



