87 



solution containing one-tenth of a per cent, carbonate of potash in 

 the osmometer, was 167 degrees, and with 1 per cent, of the same 

 salt 206 degrees, in five hours. With another membrane and 

 stronger solution, the rise was 863 millimeters, or upwards of 38 

 inches, in the same time, and as much water was therefore impelled 

 through the membrane as would cover its whole surface to a depth of. 

 8" 6 millimeters or one-third of an inch. The chemical action must be 

 different on the substance of the membrane, at its inner and outer 

 surfaces, to induce osmose ; and according to the hypothetic view 

 which accords best with the phenomena, the action on the two sides 

 is not unequal in degree only, but also different in kind. It appears 

 as an alkaline action on the albuminous substance of the membrane, 

 at the inner surface, and as an acid action on the albumen at the 

 outer surface. The most general empirical conclusion that can be 

 drawn is, that the water always accumulates on the alkaline or basic 

 side of the membrane. Hence, with an alkaline salt, such as car- 

 bonate or phosphate of soda in the osmometer, and water outside, 

 the flow is inwards. With an acid in the osmometer, on the con- 

 trary, the flow is outwards, or there is negative osmose, the liquid 

 then falling in the tube. In the last case the water outside is basic 

 when compared with the acid within, and the flow is therefore still 

 towards the base. The chloride of sodium, chloride of barium, chlo- 

 ride of magnesium, and similar neutral salts, are wholly indifferent, or 

 appear only to act in a subordinate manner to some other active acid 

 or basic substance, which last may be present in the solution or 

 membrane only in the most minute quantity. Salts which admit of 

 dividing into a basic subsalt and free acid exhibit an osmotic activity 

 of the highest order. Such are the acetate and various other salts 

 of alumina, iron and chromium, the protochloride of copper and tin, 

 chloride of copper, nitrate of lead, &c. The acid travels outwards 

 by diffusion, superinducing a basic condition of the inner surface of 

 the membrane and an acid condition of the outer surface, the favour- 

 able condition for a high positive osmose. The bibasic salts of pot- 

 ash and soda, again, although strictly neutral in properties, such as 

 the sulphate and tartrate of potash, begin to exhibit a positive osmose, 

 in consequence, it may be presumed, of their possible resolution into 

 an acid supersalt and free alkaline base. 



