PROFESSOR GRAHAM ON THE DIFFUSION OF LIQUIDS. 
41 
Another series of experiments was made upon a 1 per cent, solution of the same 
salts at a mean temperature of 64°’9. Six phials of each solution were diffused, and 
the water of two jars afterwards evaporated together, so that the quantities stated 
are double. 
The diffusion product in three experiments with the sulphate of soda was 4‘77, 
4*75 and 4'80 grs. ; mean 4‘77 grs. The diffusion product in three experiments with 
the carbonate of soda was 4'61, 4’68 and 4'67 grs.; mean 4'65 grs. The difference 
between the carbonate and sulphate is O'] 2 gr. ; it is less for the present proportion 
of 1 per cent, of salt, than for 2 per cent., so that the diffusion of the salts may be 
converging to a perfect equality in very weak solutions. One-half of the preceding 
quantities, or the mean results for a single diffusion cell, are — 
Diffusion of 1 per cent, solutions at 64°'9. 
Carbonate of soda, 2*32 grs. 100 
Sulphate of soda, 2'38 grs 102'58 
(2.) The diffusion of the carbonate of soda was further compared with the nitrate of 
the same base, to find whether their times of equal diffusion are related like those of 
the corresponding potash salts. The mean temperature of the first seven days, which 
was the period of diffusion for the nitrate of soda, was 66°'9 ; of the last three days, 
65°'2 ; and of the whole period of 9*9 days occupied by the carbonate of soda, 66°'4. 
The 4 per cent, solutions were employed. 
The nitrate of soda gave a diffusion product, in three experiments, of 1T48, 11 '58 
and 12'13grs. ; mean ll'73grs. 
The carbonate of soda, in three experiments, gave 1T66, 1T53 and 1 T52 grs.; 
mean 1 1'57 grs. A slight addition should be made to the latter quantity to raise the 
diffusion product from 66°'4 to 66°'9. It will appear from a subsequent experiment 
that the diffusion of the carbonate of soda increases 0'096 gr. for a rise of one degree 
of temperature ; which will give 0'05 gr. for the half degree in question. Bringing 
the diffusion of the two salts to the same temperature of 66°'9, we have therefore 
diffused, of — 
Nitrate of soda, in seven days, ll'73grs 100 
Carbonate of soda, in 9'9 days, ir62grs 99'06 
The difference in the quantity diffused of the two salts is only O'l 1 gr., or 1 per cent., 
which is quite within the unavoidable errors of observation. 
(3.) The diffusion of a 2 per cent, solution of the same salts was repeated at the same 
inferior temperature of 54°'3 as with the salts of potash, and under the same diffi- 
culties from fluctuation of atmospheric temperature. Two water-jars were evapo- 
rated together, so that the results are double. 
Nitrate of soda, diffused for seven days at a mean temperature of 54°'3, gave 
10'15, 10'24 and 9'92 grs. in three experiments ; mean lO'lO grs. 
MDCCCL. G 
