PROFESSOR GRAHAM ON THE DIFFUSION OF LIQUIDS. 
489 
The present results, from 2 per cent, solutions of these salts, are as follows : — 
Sulphate of potash in 8'083 days at 59°'8 . . . ir67 100 
Sulphate of soda in 9 9 days at 59°"6 .... ir76 100'94 
The diffusion in the selected times appears therefore to be, as nearly as possible, 
equal at the present temperatures. 
Another experiment may be recorded at present, of which the object was to ascer- 
tain the influence of free sulphuric acid upon the diffusion of sulphate of soda. 
7. Sulphate of soda, 2 02 per cent., to which an equivalent quantity of sulphuric 
acid was added, had the density T02703. This solution, diffused into pure water, in 
eight cells, at 59°‘6, for the same time as the preceding sulphate of soda, gave a dif- 
fusate of 9‘70, 10‘06, 10T7 and 10*29 grs. of sulphate of soda; mean 10*05 grs. in 
two cells ; calculated for 2 per cent., this diffusate becomes 9*95 grs. The presence 
of one equivalent of sulphuric acid appears therefore to diminish the diffusion of sul- 
phate of soda considerably, namely, from 11*76 to 9*95 grs., or from 100 to 84*61. 
The free sulphuric acid diffused in the experiment was not determined. 
Sulphite of Potash. — It was curious to observe how far this and other salts of the 
oxygen acids of sulpliur correspond with the sulphates. Time of diffusion 8*083 days. 
The diffusate was treated with sulphuric acid and estimated in the form of neutral 
sulphate of potash. 
1*90 per cent, of sulphite of potash, density 1*01753, diffused at 59°*5, in eight cells, 
gave 11*36, 10*72, 11*22 and 10*90 grs. in two cells; mean 11*05 grs. in two cells; 
calculated for 2 per cent., 11*63 grs. 
Making the comparison for 2 per cent, solutions we have — 
Sulphate of potash at 60°*3 . . . 11*60 100 
Sulphite of potash at 59°*5 . . . 11*63 100*26 
The two salts appear to have the same diffusibility. 
Sulphite of Soda. — Time of diffusion 9*9 days. The diffusate was estimated in 
the same manner as the preceding salt. 
2*26 per cent, of sulphite of soda, density 1*02330, diffused at 59°*6, in eight cells, 
gave 12*93, 13*35, 13*56 and 13*62 grs. in two cells; mean 13*37 grs. in two cells; 
calculated for 2 per cent., 11*83 grs. 
The comparative diffusion of the sulphites of the two bases is as follows : — 
Sulphite of potash in 8*083 days at 59°*5 ... 11*63 100 
Sulphite of soda in 9*9 days at 59°*6 11*83 100*72 
The sulphites of potash and soda appear therefore to exhibit the usual relation of 
these two bases. 
Hyposulphite of Potash. — Time of diffusion 8*083 days. The diffusate was eva- 
porated to dryness with sulphuric acid, ignited and estimated from the sulphate pro- 
duced. 
