278 Prof. Graham on the Diffusion of Liquids. 



was taken during cold weather to repeat the experiments at a 

 low temperature. 



(4.) Solutions of 1 salt in 100 water were diffused from 

 eight solution cells, for each salt. The times were increased, 

 but the same ratio of 1 to 1*4142 was preserved between them. 

 The liquids of the cells were found to retain a temperature 

 ranging slowly between 41° and 38°*8 during the whole period 

 of the observations. Sulphate of potash was substituted for 

 the carbonate, as of these two equi-diffusive salts the former 

 had been found to be least in accordance with nitrate of pot- 

 ash, in the 4 per cent, solutions, and appeared therefore to 

 afford the severest test of the relation. 



For nitrate of potash, at a mean temperature of 39°*7, du- 

 ring nine days, the diffusion product of two cells together was 

 6-97, 6-93, 6-77 and 6*64 grs. ; mean 6*83 grs. for two cells. 



For sulphate of potash, at the same mean temperature of 

 39°* 7, during 12*728 days (twelve days, seventeen hours, 

 twenty-eight minutes), the diffusion product of two cells 

 together was 7*05, 6*93, 7*28 and 6*90 grs. ; mean 7*04 grs. 

 for two cells. 



The general results are — 



Nitrate of potash in nine days at 39°*7 . 6*83 grs. 100 

 Sulphate of potash in 12*728 days at 39°*7 7*04 grs. 103*07 



(5.) Solutions of 2 salt in 100 water were diffused simulta- 

 neously with the preceding experiments, and in precisely the 

 same conditions of time and temperature. 



The diffusion product of nitrate of potash during nine days, 

 at a mean temperature of 39°*7, was 7*03, 6*63, 6*83 and 6*83 

 grs. for one cell ; mean 683 grs. for one cell, or the same num- 

 ber as for two cells with the 1 per cent, solution. 



The diffusion product of sulphate of potash during 12*728 

 days was 6*84, and 6*80 ; mean 6*82 grs. for one cell. These 

 experiments almost coincide with the number for nitrate of 

 potash. 



Nitrate of potash, 6*83 grs. . . < 100 

 Sulphate of potash, 6*82 grs. . . 99*85 



(6.) The existence of the relation in question was also se- 

 verely tested in another manner. Preserving the ratio in the 

 times of diffusion for the two salts, the actual times were varied 

 in duration, in three series of experiments, as 1, 2 and 3. 

 The experiments were made in the vault, with a uniformity 

 of temperature favourable to accuracy of observation. Eight 

 cells of the 1 per cent, solution of each salt were always dif- 

 fused at the same time. 



(a.) Nitrate of potash diffused for 3*5 days, at 47°*2, gave 



