32 
PROFESSOR GRAHAM ON THE DIFFUSION OF LIQUIDS. 
the addition of acetate of potash, which appeared to belong to the same class, the 
solution employed being that of I salt to 100 water. The experiments were made in 
a vault, of which the temperature was nearly uniform, falling in a gradual manner 
from 59° to 58°, with a mean of 58°’5 during the period of seven days which the dif- 
fusion lasted. Eight phials of each salt were diffused, and the liquids of four water- 
jars evaporated together. 
Carbonate of potash gave 10‘42 and 10'59 grs. of salt diffused: mean 10"51 grs., or 
•2’U3 grs. for one cell. 
Sulphate of potash gave 10*72 and 10*78 grs, of salt diffused: mean 10*75 grs,, or 
2*69 grs. for one cell. 
Acetate of potash, its diffusion product being treated with an excess of hydrochloric 
acid, gave 8*30 and 8*04 grs, of chloride of potassium, equivalent to 10*91 and 10*57 
grs. of acetate of potash ; mean 10*74 grs. of acetate of potash, or 2*68 grs. for one 
cell. The diffusion of these three salts is therefore remarkably similar : — 
Diffusion of 1 per cent, solutions at 58°*5. 
Carbonate of potash .... 2*63 grs. 
Sulphate of potash .... 2*69 grs. 
Acetate of potash 2*68 grs. 
The 1 per cent, solution of neutral or yellow chromate of potash in good crystals 
gave 11*28 and 11*35 grs.; mean 11*31 grs., or 2*83 grs. for each ceil. It was re- 
marked of the diffused chromate in this experiment, that it contained a sensible 
quantity of green oxide of chromium. The diffusion of a salt appears indeed to try 
its tendencies to decomposition very severely. 
The bicarbonate of potash gave 8*83 and 8*35 grs. of chloride of potassium, the 
diffusion product being neutralized with hydrochloric acid; equivalent to 11*25 and 
11*21 grs. of bicarbonate of potash; mean 11*23 grs., or 2*81 grs. for one cell. 
The bichromate of potash gave 11*54 and 11*49 grs. of salt diffused; mean 11*51 
grs., or 2*88 grs. for one cell. These last three salts give all a larger diffusion pro- 
duct than the preceding three, while they agree well together. It is doubtful whether 
this excess in their diffusion is occasioned by a partial decomposition in the act of 
diffusion, which might be of such a kind as to increase the real or apparent diffusion 
in every one of them, or whether it is a peculiar character of this little group, to 
which the ferricyanide of potassium, it will be afterwards seen, falls to be added, 
while the ferrocyanide appears to belong to the other group : — 
Diffusion of 1 per cent, solutions at 58°*5. 
Chromate of potash .... 2*83 grs. 
Bicarbonate of potash . . . 2*81 grs. 
Bichromate of potash .... 2*88 grs. 
The divergence from each other of two salts so closely isomorphous as sulphate and 
