182 
PROFESSOR GRAHAM ON OSMOTIC FORCE. 
Chlorides ot barium and strontium both gave 18 ms. ; nitrate of strontia, 5 ms. ; sul- 
phate of magnesia, 0’5 per cent., 2 ms. ; 1 per cent., 2 ms. ; 2 per cent., 3 ms. ; sulphate 
of zinc was very similar, +2 to —2 ms., from 05 to 2 per cent. ; chloride of mercury, 
1 per cent., gave 6 and 8 ms. in two experiments. 
2. Substances of an intermediate degree of osmotic force ; osmose from 20 to 35 
degrees. Sulphurous acid gave 20 ms. Certain vegetable acids have a similar osmose. 
Tartaric acid, in solutions of 0-25, 1 and 4 per cent., gave 24, 26 and 28 ms. ; citric 
acid, 1 per cent., 30 ms. Also monobasic acids, such as hydrochloric acid, nitric 
acid, acetic acid, have the same moderate osmotic action in porous earthenware. 
3. Substances of considerable osmotic power in porous earthenware ; osmose from 
35 to 55 ms. 
In this class are found the polybasic mineral acids : sulphuric acid, 0 - 5 per cent., 
gave even 63 ms. ; 2 per cent., 54 ms., or nearly the same osmose as the smaller 
proportion of acid. 
In another earthenware cylinder, the following observations on the osmose of 
sulphuric acid were successively made : — 
OT per cent 43 and 43 ms. 
1 per cent 40 and 40 ms. 
4 per cent 41 and 39 ms. 
10 per cent 38 and 39 ms. 
The results exhibit much similarity of osmose through a great range (1 to 100) in 
the proportion of acid. So small a quantity of this acid as 1 part in 1000 water, 
appears to give as great an osmose as any larger proportion of acid. 
Certain neutral salts, sulphate of potash, sulphate of soda, sulphate of ammonia, 
belong to the same class. 
With sulphate of soda the osmose for the different proportions 0T25, 0*25, 1 and 
4 per cent, of salt, was 46, 4 7, 36 and 24 ms. respectively ; the osmose diminishing 
with the increased proportion of salt. 
Of sulphate of potash, 025 per cent, gave 51 ms. ; 1 per cent. 46 ms., and 4 per cent. 
38 ms., showing no great change from one quarter to 4 per cent. ; chromate of pot- 
ash, 1 per cent., gave an osmose of 54 ms. 
4. Substances exhibiting the highest degree of osmotic power in porous earthen- 
ware. 
Salts of the alkalies, possessing either a decided acid or alkaline reaction, and 
certain neutral salts of potash. 
Binarseniate of potash gave 66 ms. ; Rochelle salt 82 ms. 
With binoxalat.e of potash the osmose observed in an earthenware osmometer was — 
For 0‘02 per cent. . . . 
0’05 per cent. . . . 
0T per cent. . . . 
. . 32 ms. 
. . 55 ms. 
. . 63 ms. 
