PROFESSOR GRAHAM ON THE DIFFUSION OF LIQUIDS. 
23 
with an equal or greater quantity of another salt B, as a gas a freely diffuses into the 
space already occupied by another gas h ; the gas h in return diffusing at the same 
time into the space occupied by a. Or whether, on the contrary, the diffusion of the 
salt A is resisted by B. The latter result would indicate a neutralization of the water’s 
attraction, and a kind of equivalency or equality of power and exchangeability of dif- 
ferent salts, in respect of that effect, which would divide entirely the phenomena of 
liquid from those of gaseous diffusion. 
(1.) A solution of 4 parts of carbonate of soda to 100 water, of density T0406, was 
placed in the six-ounce diffusion phial of lT75inch aperture, and allowed to commu- 
nicate with 24 ounces of water. 
Two similar diffusion phials, equally charged, were immersed in 24 ounces of a solu- 
tion of 4 parts of chloride of sodium to 100 water, having the density 1‘0282. The 
diffusion proceeded for eight days, in all cases, at 64°. The proportion of carbonate 
of soda found without in the water-jar afterwards, was ascertained by an alkalime- 
trical process, the neutralization being effected at the boiling-point. The following 
are the results : — 
Experiment I. Diffusion product into water . . . 
Experiment II. Diffusion product into solution of 
chloride of sodium 
Experiment III. Diffusion product into solution of 
chloride of sodium 
9’06 grs. of carbonate of soda. 
8’82 grs. of carbonate of soda. 
9*10 grs. of carbonate of soda. 
It thus appears that 4 per cent, of chloride of sodium present in the water atmo- 
sphere of the jar has no sensible effect in retarding the diffusion into it, from the 
solution cell, of carbonate of soda from a solution containing also 4 per cent, of 
the latter. 
(2.) The experiment was varied by allowing the solution of carbonate of soda to 
diffuse into a solution of sulphate of soda, a salt more similar to the former in solu- 
bility and composition. The solution of the latter, containing 4 per cent., was of 
density T0352. The temperature and period of diffusion were the same as before: — 
Experiment IV. Diffusion product into solution ofV , 
, , ^ , > 7'84 grs. of carbonate of soda, 
sulphate of soda J 
Experiment V. Diffusion product into solution of l ^ , 
, , ^ , > 7‘82 grs. of carbonate of soda, 
sulphate of soda J 
Here we find a small reduction in the quantity of carbonate of soda diffused, 
amounting to one-eighth of the whole. The sulphate of soda has therefore exercised 
a positive interference in checking the diffusion of the carbonate to that extent. So 
small and disproportionate an effect however is scarcely sufficient to establish the 
existence of a mutual elasticity and resistance between these two salts. 
Still it might be said, may not the diffusion of one salt be resisted by another salt 
which is strictly isomorphous with the first ? 
