IklE. T. GEAHAM ON LIQUID DIPEUSION APPLIED TO ANALYSIS. 
195 
Here the separation is still more sensible than before with the bases. The six upper 
strata contain 263 milligrammes of salt, of which 239 milligrammes, that is 90-8 per 
cent., are chloride of sodium. The salt of the upper eight strata amounts to 695 milli- 
grammes, of which 583 milligrammes, or 83'9 per cent., are chloride of sodium. 
How long the ditfnsion should be continued in a liquid column of limited height, 
such as in these experiments, so as to produce the greatest separation, is a question of 
some interest, which can only be answered by experiment. The last diffusion was 
accordingly repeated, with the difference that it was continued for double the former 
time. 
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 stratum. 
Chloride of sodium, 
in grammes. 
Sulphate of soda, 
in grammes. 
Total diifusate, 
in grammes. 
1 
•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 milligrammes of salt, of which 562 milligrammes, or 85T per cent., are chlo- 
ride 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 0‘7, 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 possibly be favoured in 
another manner. In the preceding experiments (Table VI.) the two metals were in 
2 E 2 
