276 Prof. Graham on the Diffusion of Liquids. 



square root of 2 to the square root of 1 ; the densities of these 

 gases being 16 and 8, which are as 2 to 1. The densities are 

 the squares of the equal-diffusion times. It is not therefore 

 the times themselves of equal diffusion of two salts, but the 

 squares of those times which are likely to exhibit a simple 

 relation. 



(1.) While the 4 per cent, solution of nitrate of potash was 

 diffused as usual for seven days, the corresponding solution 

 of carbonate of potash was now allowed to diffuse for 9*90 

 days; times which are as 1 to 1*4 142, or as 1 to the square 

 root of 2. 



The results were as follows: diffused of — 



Nitrate of potash at 64°-l, in seven days, 13*81 grs. 100 

 Carbonate of potash at 64°*3, in 9*9 days, 13*92 grs. 100-8 



The three experiments on the nitrate of potash, of which 

 13-81 grs. is the mean, were 13*98, 13*86 and 13*60 grs., as 

 already detailed. The three experiments on the carbonate 

 were 14*00, 13*97 and 13*78 grs. The difference in the means 

 of the two salts is only 0*11 gr. The results appear to be as 

 near to equality as could be reasonably expected from the 

 method of experimenting. Seven and 9*90 may therefore be 

 considered as the times of equal diffusion indicated for nitrate 

 and carbonate of potash. The times of equal diffusion, or the 

 diffusibilities of nitrate and carbonate of potash, would appear 

 therefore to be in the proportion of the square root of 1 to 

 the square root of 2. 



The explanation of such a relation suggested by gaseous 

 diffusion has been anticipated. It is that the two salts have 

 different densities in solution, that of nitrate of potash being 

 1, and that of carbonate of potash 2. We are thus led to 

 ascribe, what may be called Solution Densities, to the salts. 

 The two salts in question are related exactly like protocarbu- 

 retted hydrogen gas, of density 1, to oxygen gas of density 2. 

 The parallel would be completed by supposing that the single 

 volume of oxygen to be diffused was previously mixed with 

 100 volumes of air (or any other diluting gas), while the 2 

 volumes of protocarburetted hydrogen were also diluted with 

 100 volumes of air; the diluting air here representing the 

 water in which the salts to be diffused are dissolved in the 

 solution cell. The time in which a certain quantity of proto- 

 carburetted hydrogen would come out from a vessel contain- 

 ing 1 per cent, of that gas being 1 (the square root of den- 

 sity 1), the time in which an equal quantity of oxygen w r ould 

 diffuse out from a similar vessel containing 1 per cent, also 

 would be 1*4142 (the square root of density 2). 



