Prof. Graham on the Diffusion of Liquids, 277 



(2.) A solution of 4 parts of sulphate of potash in 100 water 

 was diffused simultaneously with the last solution of carbonate 

 of potash, and therefore in similar circumstances. The diffu- 

 sion products of three experiments were 14*46, 14*21 and 

 14*53 grs.; mean 14*40 grs. This is in the proportion of 

 104*27 sulphate of potash to 100 nitrate of potash; so that 

 the approximation to equality of diffusion with nitrate of pot- 

 ash, in the selected times, is not so close for the sulphate as 

 for the carbonate of potash. 



(3.) The diffusion was repeated of 2 per cent, solutions of 

 the nitrate and carbonate of potash at a lower temperature by 

 about 10°. The temperature of the solutions was rather un- 

 steady; ranging from 56° to 52°*25 for the first period of 

 seven days, from 56° to 50°- 5 for the period of 9*90 days, and 

 from 55° to 50°*5 for a second period of seven days ; the ex- 

 ternal atmospheric temperature having fallen during the same 

 period more than 20 degrees. Six phials of each solution 

 were diffused and evaporated two together ; so that the results 

 are all double quantities. 



At a mean temperature of 54°*3, the nitrate of potash gave 

 in seven days 12*60 and 12*13 grs.; mean 12*36 grs. 



Again, at a mean temperature of 52°*4, the nitrate of potash 

 gave in seven days 11*85, 12*40 and 11*95 grs.; mean 

 12*06 grs. 



The carbonate of potash gave in 9*90 days, with a mean 

 temperature of 53°'4, 12*69, 12*40 and 12*12 grs.; mean 

 12*40 grs. 



The general results are — 



Nitrate of potash, in seven days, at 54°*3 . 12*36 grs. 

 Carbonate of potash, in 9*9 days, at 53°*4 . 12*40 grs. 

 Nitrate of potash, in seven days, at 52°*4 . 12*06 grs. 



As the first nitrate is 0°*9 above the carbonate and the second 

 nitrate 1° below it, we may take the mean of the two nitrates 

 as corresponding to the temperature of the carbonate. We 

 thus finally obtain, diffused at 53°*4, of — 



Nitrate of potash in seven days, 12*22 grs. . 100 

 Carbonate of potash in 9*9 days, 12*40 grs. . 101*47 



The difference in the amount of the diffusion of the two salts 

 in these times is only 0*18 gr., or l| per cent. 



These last experiments may be held therefore as tending to 

 the same conclusion as the former series, although the circum- 

 stances were more than usually unfavourable to their success. 

 To find whether the same relation existed between the salts 

 through a considerable range of temperature, an opportunity 



