342 Prof. Graham on the Diffusion of Liquids, 



was 42° the first day, 38° the second, and 37° steadily for the 

 remainder of the period ; the mean being 37°'7. 

 The mean results at 64° are as follows : — 





2. 



4. 



6| 



10. 



Carbonate of soda 



Sulphate of soda 



4-14 

 4-31 



7-78 



8-17 



12-22 

 13-50 



16-88 

 19*14 



Another series of experiments was made upon a 1 per cent, 

 solution of the same salts at a mean temperature of 64°'9. Six 

 phials of each solution were diffused, and the water of two 

 jars afterwards evaporated together, so that the quantities 

 stated are double. 



The diffusion product in three experiments with the sul- 

 phate of soda was 4*77, 4*75 and 480 grs.; mean 4*77 grs. 

 The diffusion product in three experiments with the carbonate 

 of soda was 4*61, 4'68 and 467 grs.; mean 4*65 grs. The 

 difference between the carbonate and sulphate is 0°12 gr. ; it 

 is less for the present proportion of 1 per cent, of salt, than 

 for 2 per cent., so that the diffusion of the salts may be con- 

 verging to a perfect equality in very weak solutions. One- 

 half of the preceding quantities, or the mean results for a single 

 diffusion cell, are — 



Diffusion of 1 per cent, solutions at 64 °- 9. 



Carbonate of soda, 2*32 grs. . . 100 

 Sulphate of soda, 2*38 grs. . . 102-58 



(2.) The diffusion of the carbonate of soda was further 

 compared with the nitrate of the same base, to find whether 

 their times of equal diffusion are related like those of the cor- 

 responding potash salts. The mean temperature of the first 

 seven days, which was the period of diffusion for the nitrate 

 of soda, was 66°*9 ; of the last three days, 65°*2; and of the 

 whole period of 9*9 days occupied by the carbonate of soda, 

 QQ°'\>. The 4 per cent, solutions were employed. 



The nitrate of soda gave a diffusion product, in three ex- 

 periments, of 11-48, 11*58 and 12-13 grs.; mean 11-73 grs. 



The carbonate of soda, in three experiments, gave 11*66, 

 11-53 and 11*52 grs.; mean 11*57 grs. A slight addition 

 should be made to the latter quantity to raise the diffusion 

 product from 66°-4 to 66 0, 9. It will appear from a subsequent 

 experiment that the diffusion of the carbonate of soda in- 

 creases 0-096 gr. for a rise of one degree of temperature ; 

 which will give 005 gr. for the half degree in question. 



