PROFESSOR GRAHAM ON THE DIFFUSION OF LIQUIDS. 
39 
Such a result indeed is not inconsistent with the times of equal diffusion of these two 
substances, differing as much as 1 to 2. 
(2.) Of pure fused hydrate of potash, a 1 per cent, solution was diffused from four 
cells for 4*95 days at a mean temperature of 53°'7, against a 1 per cent, solution of 
nitrate of potash in six cells, for seven days, at a mean temperature 0°'l lower, or of 
53°'6. The hydrate of potash which diffused, is calculated as before from the chloride 
of potassium which it gave, when neutralized by hydrochloric acid. Hydrate of 
potash diffused from two cells 5 '97 and 6'28 grs. ; mean 6' 12 grs., or 3'06 grs. for a 
single cell. 
Nitrate of potash diffused from two cells 6'22, 6'54 and 5'93 grs ; mean 6'23 grs., 
or 3' 11 grs. for a single cell. The diffusion of nitrate of potash being 100, that of the 
hydrate of potash is 98'2, numbers which are sufficiently in accordance. But the 
times were as 1 to T4142, and their squares as 1 to 2. So far then as this series of 
experiments on hydrate of potash entitles us to conclude, we appear to have for the 
salts of potash a close approximation to the following simple series of squares of 
equal diffusion times : — 
Squares of Times of Equal Diffusion, or Solution Densities. 
Hydrate of potash . . . . 1 
Nitrate of potash .... 2 
Sulphate of potash .... 4 
(3.) The hydrate of potash was also diffused at the lower temperature, 39°'7, in 
company with the nitrate and sulphate of potash for a period of 6'364 days (six days, 
eight hours, forty-four minutes). 
The 1 per cent, solution of hydrate of potash gave in eight cells, evaporated two 
together, 6*93, 6 93, 6'93 and 6 89 grs. ; mean 6'92 grs. 
The 2 per cent, solution of hydrate of potash gave in three single cells, 6'77, 6*49 
and 7’ 10 grs. ; mean 6'79 grs. 
The diffusion of nitrate of potash in nine days at the same temperature, as already 
detailed, was sensibly the same, or 6'83 grs. for both the 1 and 2 per cent, solutions. 
The times for the two salts were as 1 to T4142. 
The diffusion of hydrate of potash, at 39°'7, may therefore be stated with reference 
to that of nitrate of potash, for the selected times, as follows : — 
Nitrate of potash, 1 and 2 per cent, solutions 100 
Hydrate of potash, 1 per cent, solution 10r3 
Hydrate of potash, 2 per cent, solution 99'4 
These experiments at the low temperature concur, therefore, with those made at 
the higher temperature, in proving that the times of equal diffusion of the two sub- 
stances have been properly chosen. 
