PROFESSOR GRAHAM ON THE DIFFUSION OF LIQUIDS. 
823 
3. 4'005 per cent, of sulphate of zinc, density 1'04146, diffused at 65°‘4, in four cells, 
11*63, 11 * 70 , 11*00, 11*95; mean 11*57 gi’s. for one cell; calculated for 4 per cent., 
11*56 grs. of sulphate of zinc in one cell at 65°*4. 
4. 8*01 per cent, of sulphate of zinc, density 1*08063, diffused at65°*4, in four cells, 
21*22, 20*52, 21*06, 21*84; mean 21*16 grs. for one cell; calculated for 8 per cent., 
21*13 grs. of sulphate of zinc in one cell at 65°*4. 
5. 8*04 per cent, of sulphate of zinc, density 1*08084, diffused at 62°*8, in four cells, 
20*70, 18*57, 20*32, 20*36; mean 19*99 grs. for one cell; calculated for 8 per cent., 
19*81 grs. of sulphate of zinc in one cell at 62°*8. 
6. 16*08 per cent, of sulphate of zinc, density 1*15734, diffused at 62°*8, in four cells, 
36*70, 37*15, 37*51, 38*21 ; mean 37*39 grs. for one cell; calculated for 16 per cent., 
37’20 grs. of sulphate of zinc in one cell at 62°*8. 
7- 24*11 per cent, of sulphate of zinc, density 1*23156, diffused at 62°*8, in three cells, 
51*12, 50*14, 51*66; mean 50*97 gi’S. for one cell; calculated for 24 per cent., 50*71 
grs. of sulphate of zinc in one cell at 62°*8. 
Diffusion of Sulphate of Zinc in 16*16 days at 65°*4 ; two cells. 
From 1 per cent, solution .... 
Grs. 
6-67 
Ratio. 
1*091 
From 2 per cent, solution .... 
12*22 
2 
From 4 per cent, solution .... 
23*12 
3*784 
From 8 per cent, solution .... 
42*26 
6*916 
From 8 per cent, solution at 62°*8 
39*62 
1 
From 16 per cent, solution at 62°-8 . 
74*40 
1*878 
From 24 per cent, solution at 62°*8 .. 
101*42 
2*560 
It will be remarked that the diffusion of these two isomorphous salts, sulphate of 
magnesia and sulphate of zinc, differs so much, in the 1 per cent, solution, as 7’31 to 
6*67, that is, as 100 to 91*25 ; or 8*75 per cent. This I have no doubt, however, is 
an accidental error, the disturbances from changes of temperature and other causes of 
dispersion being in direct proportion to the duration of the experiment, and there- 
fore much increased with these long times ; while the 1 per cent, solution also appears 
to be generally the proportion most exposed to such errors. The sulphate of zinc 
appears to be the truest throughout, in its diffusion, of these two salts. The approach 
to equality becomes close in the 4 per cent, and larger proportions of salt, parti- 
cularly with the unusually high proportions of 16 and 24 per cent., which were ob- 
served in these salts. The diffusion of both salts falls off remarkably in the higher 
proportions. The result of the comparison of these two magnesian sulphates is no 
doubt favourable to the similarity of diffusion of isomorphous salts. 
