192 
PROFESSOR GRAHAM ON OSMOTIC FORCE. 
Racemic acid, 1 per cent., gave 4, 11 and 7 ms. in three experiments, at 55°, in the 
last used membrane; with 15 and 22 ms. at the same temperature in albumen; or 
was always slightly positive like tartaric acid. 
Acetic acid, in the proportions of CPI, 0’5 and 1 per cent., gave sensibly the same 
small positive osmose, 25 to 28 ms., at 57° to 62°, in membrane. 
A saturated solution of carbonic acid in water gave 25 and 26 ms. in membrane, 
with 20 and 22 ms. in albumen, both at 65°. 
The last solution, diluted with an equal bulk of water, gave an osmose of 15 and 
18 ms. in membrane, and 16 ms. twice in albumen, both at 63°. 
Terchloride of gold is negative in its osmose like the stronger acids, giving —49 
and —54 ms. in membrane, at 64°, with much reduction of metallic gold in the sub- 
stance of the membrane. 
Bichloride of platinum, made as neutral as possible by evaporation, gave for the 
1 per cent, solution —32 and —30 ms. in membrane, at 61°. For the 0T per cent, 
solution, a positive osmose of 27, 14 and 5 ms. in three successive experiments made 
with the last membrane, at 64°, 65° and 62°. The same 1 per cent, solution gave in 
albumen, at 61°, a positive osmose of 54 and 50 ms. ; the 0*1 per cent, solution also, 
at 64°, gave 43 ms. Albumen appears thus to be less adapted for bringing out the 
negative osmose of various substances than membrane is. 
In membrane, bichloride of tin, 0T per cent., gave —24 ms., at 61°; 1 per cent. 
—46 and —71 ms., at 59°. The addition to the last of 0‘5 per cent, of sulphuric acid 
gave —63 ms., or did not alter the character of the osmose. But partial neutraliza- 
tion of the 1 per cent, tin solution, by ammonia, on the other hand, gave 0 m., or 
destroyed all osmose. One per cent, of bichloride of tin gave only a small negative 
osmose in albumen, namely 5 ms. twice, at 59°. 
Oxalic acid carries the highly negative character of its osmose into the binoxalate 
of potash, of which 1 per cent, of anhydrous salt gave in membrane —112 and 
— 99 ms., at 62°; 0T per cent., —30 ms., at 60°. One per cent, of the same salt in 
albuminated calico gave —20 ms., at 60°. A saturated solution of binoxalate of 
potash, containing 2’5 per cent, of salt, gave —15 ms. in the last osmometer. 
Bisulphate of potash, 1 per cent., gave 4 and 7 ms. in membrane, at 56° ; in albumen, 
7, 3 and 6 ms., at 56°. 
A solution of bitartrate of potash, saturated in the cold, also gave a small positive 
osmose, namely 4 and 2 ms. in membrane, and 20 and 17 ms. in albumen, both 
at 56°. Other supersalts tried gave also a small positive osmose, such as binarseniate 
of potash and bichromate of potash. It becomes doubtful therefore whether any of 
the supersalts of potash are negative, except the acid oxalates of that base. 
Neutral organic substances dissolved in water appear to be generally deficient in 
the power to give rise in membrane to that osmose which depends upon a small 
quantity of the soluble substance, such as 1 per cent., or a still less proportion. The 
osmose obtained in ox-bladder employed without removing the muscular coat, was, 
