Prof. Graham on the Diffusion of Liquids. 343 



Bringing the diffusion of the two salts to the same temperature 

 of 66°*9, we have therefore diffused, of — 



Nitrate of soda, in seven days, 11*73 grs. . 100 

 Carbonate of soda, in 9*9 days, 11*62 grs. . 99*06 



The difference in the quantity diffused of the two salts is only 

 0*11 gi\, or 1 per cent., which is quite within the unavoidable 

 errors of observation. 



(3.) The diffusion of a 2 per cent, solution of the same salts 

 was repeated at the same inferior temperature of 54°*3as with 

 the salts of potash, and under the same difficulties from fluc- 

 tuation of atmospheric temperature. Two water-jars were 

 evaporated together, so that the results are double. 



Nitrate of soda, diffused for seven days at a mean tempera- 

 ture of 54°*3, gave 10*15, 10*24 and 9*92 grs. in three expe- 

 riments; mean 10' 10 grs. 



Carbonate of soda, diffused for 9*9 days at a mean tempe- 

 rature of 53°*4, gave 9*93, 9*54 and 10*10 grs. in three expe- 

 riments; mean 9*86 grs. But the latter amount is to be in- 

 creased by 0*09 gr. to bring it to the diffusion of 54°*3. We 

 have then for the diffusion product of the two salts at the same 

 temperature of 54°*3 — 



Nitrate of soda, in 7 days, 10*10 grs. . 100 

 Carbonate of soda, in 9*9 days, 995 grs. 98*51 



The difference is again small, namely, 0*15 gr., or 1^ per 

 cent., and within the limits of unavoidable error. 



It appears therefore that the times of equal diffusion of the 

 nitrate and carbonate of soda are related like those of the ni- 

 trate and carbonate of potash, or as the square root of 1 and 

 2, that is, as 1 to 1*4142. 



Relation of Salts of Potash to Salts of Soda. 



It appeared probable, from many of the experiments already 

 recorded, that if any relation, in the times of equal diffusibility, 

 existed between the corresponding salts of potash and soda, it 

 was that of the square root of 2 to the square root of 3. They 

 were accordingly diffused lor times having this ratio; namely, 

 the nitrate of potash for seven days, the nitrate of soda for 

 8*57325 days ; the sulphate and carbonate of potash for 9*9 

 days, and the sulphate and carbonate of soda for 12*125 days. 

 If these times are rightly chosen, the eventual diffusion pro- 

 ducts of all the experiments should be equal. The 1 per cent, 

 solution was selected, and the number of experiments simul- 

 taneously made on each salt was eight or six. The liquids of 

 two water-jars were evaporated together, so that each of the 



