PROFESSOR GRAHAM ON OSMOTIC FORCE. 
207 
referred to (page 187), the diffusate of carbonate was also low but remarkably uniform, 
namely 0*018 gramme for 0*1 per cent, solution, 0*092 gramme for 0*5 per cent, solu- 
tion, and 0'196 gramme for the 1 per cent, solution. 
But these determinations were all made by the alkali metrical method, and when 
in subsequent observations the potash was also determined by weighing it as sulphate, 
the proportion of diffusate was found sensibly increased. It hence appears that car- 
bonate of potash acts chemically upon the membrane, and that a portion of the alkali 
diffuses out in a neutralized state. Thus in five successive experiments with the 
1 per cent, solution, in fresh double membrane, the diffusates by the alkalimetrical 
method were 0*208, 0*254, 0*264, 0*215 and 0*189 gramme carbonate of potash; 
while the actual quantity of alkali found by direct analysis corresponded in the 
last four observations to 0*318, 0*353, 0*287, and 0*242 gramme. The quantity of 
carbonate of potash which has suffered change in passing through the membrane is 
0*064, 0*089, 0*072 and 0*053 gramme in these four experiments respectively. 
The diffusates of carbonate of potash, increased by those quantities, approach too 
closely to those of chloride of sodium to warrant the supposition of any peculiar 
repression by membrane of the diffusion of carbonate of potash, which otherwise 
appeared probable. 
The observations last commented upon belong to a number undertaken with the 
view of ascertaining three points of interest, which may excuse a fuller statement of 
the experiments. These points were, first, the influence upon osmose of the air dis- 
solved in solutions of carbonate of potash, which might be supposed to take a part in 
the chemical action of the membrane; secondly, the effect of frequent repetition of 
the experiment in exhausting the osmotic activity of membrane; and, thirdly, the 
relation in osmose of an alkaline carbonate and phosphate. 
Table XV. — Solutions in Osmometer L of double membrane for five hours. 
Salt in osmometer. 
Rise in 
millimeter 
degrees. 
Temperature, 
Fahr. 
Carbonate of potash, 1 per cent 
439 
_ o 
t)3 
Same, deprived of air by boiling 
376 
64 
Same, deprived of air by boiling 
353 
65 
Same solution, unboiled 
325 
63 
Same solution, unboiled 
268 
56 i 
Phosphate of soda (2NaO HO PO,) 1 per cent 
176 
55 
Same 
194 
58 
Same, (H per cent 
196 
56 
Same, 0-1 per cent 
190 
58 
Carbonate of potash, 04 per cent. 
176 
57 
Same, 04 per cent 
227 
65 
Same, 1 per cent. 
298 
58 
Same, 1 per cent 
335 
64 
Same, 1 per cent 
312 
62 
It will be remarked that the highest osmose (439 ms.) is obtained in the first expe- 
