PROFESSOR GRAHAM ON OSMOTIC FORCE. 
211 
same two salts, in open vessels, were more nearly in the proportion of 1 to 07. 
The comparative diffusion of carbonate of soda appears to be rather repressed than 
promoted by the septum. 
The neutralization of a portion of the alkaline salt during the osmotic process is 
again indicated. The portion of carbonate of soda thus lost in the 1 per cent, solu- 
tion appears to diminish on repetition of the experiment. At the head of the table, 
the loss in two experiments is 0*065 and 0*050 gramme ; lower down, 0*069 and 
0*042 gramme; and near the bottom of the table, 0*026 and 0*027 gramme. The 
loss with the 10 per cent, solution is 0*110 and 0*092 gramme, or not more than 
double the loss in the preceding 1 per cent, solutions of carbonate of soda. 
Sulphates of Potash and Soda . — The sulphate of potash was made the subject of 
frequent experiment, with the view of obtaining light on the nature of osmose, at the 
commencement of the inquiry. But it is not well fitted for such a purpose, its action 
in the osmometer proving at first of a most perplexing character. With thick ox- 
bladder, sulphate of potash dissolved in the proportion of 1 per cent., usually exhibited 
considerable osmose, that is, about one-half of the osmose of carbonate of potash in 
similar circumstances. The osmose of the sulphate had, however, a peculiar dispo- 
sition to increase in successive repetitions of the experiment with the same mem- 
brane. The osmose of this salt might also be doubled by allowing bladder in 
substance to macerate for some time in the solution before the osmotic experiment; 
soluble matter from the membrane manifestly influenced the result considerably in 
all experiments with sulphate of potash. 
When the removal was effected of the muscular coat of bladder, the chief source 
of its soluble matter, the osmose of the salt in question fell greatly in amount instead 
of rising, like that of the carbonate of potash. 
In the prepared membrane sulphate of potash presented a small moderate osmose, 
like chloride of sodium. But the salt must be exactly neutral to test-paper, and the 
membrane also free from foreign saline matter, otherwise very different results are 
obtained. In a double membrane, 1 per cent, of the neutral sulphate gave 21 and 
20 ms. ; but the same solution, made alkaline by the addition of no more than one 
ten-thousandth part (0*01 per cent.) of carbonate of potash, started up to 101 and 
167 ms., a much greater osmose than the proportion of carbonate of potash present gave 
afterwards by itself in the same membrane, namely 19, 23, and 17 ms. The influence 
of the alkali is so persistent, that the membrane, macerated in water for a night after 
the last experiments, still gave 65 ms. with 1 per cent, of pure sulphate of potash. 
The osmotic activity of sulphate of soda is equally excited by a trace of alkali, and 
both sulphates exhibit the same character in albumen as well as in membrane. This 
remarkable result of the combined action of the two salts is so likely to elucidate the 
chemical actions prevailing in osmose, that a fuller series of illustrative experiments 
may be recorded. The septum was of double calico, well albuminated, and presented 
a good resistance to hydrostatic pressure. 
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