Mr. T. Graham on Liquid Diffusion applied to Analysis. 219 



Table VIII. — Diffusion of 5 per cent, of Chloride of Sodium 

 and 5 per cent, of Sulphate of Soda, for fourteen days, at 

 10° to 11°. 



Number of 



Chloride of 



Sulphate of 



Total diffu- 



^■fratiim 



Sodium, in 



soda, in 



sate, in 



o uiavuiiii 



grammes. 



grammes. 



grammes. 



i 



•077 



•005 



•082 



2 



•089 



•009 



•098 



3 



•105 



•014 



•119 



4 



•130 



•026 



•156 



5 



•161 



•044 



•205 



6 



•199 



•072 



•271 



7 



•240 



•111 



•351 



8 



•289 



•173 



•462 



9 



•337 



•241 



•578 



10 



•392 



•334 



•726 



11 



•433 



•433 



•866 



12 



•487 



•539 



1-026 



13 



•525 



•646 



1-171 



14 



•555 



•745 



1-300 



15 and 16 



•979 



1-609 



2-588 





4-998 



5-001 



9-999 



The salt contained in the three upper strata amounts to 299 

 milligrammes, of which 271, or 90*6 per cent, of the whole, are 

 chloride of sodium. The upper five strata yield 660 milli- 

 grammes of salt, of which 562 milligrammes, or 85*1 per cent., 

 are chloride of sodium. These proportions are not dissimilar to 

 those deduced from the former Table, and show that little is 

 gained in the way of separation by extending the diffusion-period 

 from seven to fourteen days, unless, indeed, the column of fluid 

 be increased in height at the same time. 



It might be worth observing whether the separation of two 

 unequally diffusive metals can be favoured by varying the acid, 

 or form of combination — whether, for instance, the hydrates of 

 potash and soda would not separate to a greater extent than has 

 been observed of the chlorides of potassium and sodium, the 

 separate diffusibilities of the former substances being as 1 to 07, 

 while that of the latter are as 1 to 0*841 . I have not, however, 

 pursued this branch of the subject. 



The separation of the same metals from each other may pos- 

 sibly be favoured in another manner. In the preceding experi- 

 ments (Table VI.) the two metals were in union with the same 

 acid, or rather both were in the state of chloride. But the 

 metals might be used in combination with different acids, and 

 these acids themselves might be of equal or of unequal diffusi- 

 bility. If of equal diffusibility, such as nitric and hydrochloric 

 acids, no reason appears why the acids should affect the amount 



