154 



Royal Society, 



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 phaenomena, the action on the two sides 

 is not unequal in degi'ee 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, 

 cliloride 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. 



The following Table exhibits the osmose of substances of all 

 classes : — 



Osmose of 1 per cent, solutions in Membrane. 



Degrees. 



Oxalic acid -148 



Hydrochloric acid (O'l 



perc.) - 92 



Terchloride of gold — 54 



Bichloride of tin — 46 



Bichloride of platinum... — 30 

 Chloride of magnesium... — 3 



Chloride of sodium -f 2 



Chloride of potassium ... 18 



Nitrate of soda 2 



Nitrate of silver 34 



Sulphate of potash 21 to 60 



Sulphate of magnesia ... 14 



Chloride of calcium 20 



Chloride of barium 21 



Chloride of strontium ... 26 



Chloride of cobalt 26 



Chloride of manganese ... 34 



Degrees. 



Chloride of zinc 54 



Chloride of nickel 88 



Nitrate of lead 125 to 211 



Nitrate of cadmium 137 



Nitrate of uranium 234 to 458 



Nitrate of copper 204 



Chloride of copper 351 



Protochloride of tin 289 



Protochloride of iron 435 



Chloride of mercury 121 



Protonitrate of mercury... 356 



Pernitrate of mercury 476 



Acetate of sesquioxide of 



iron 194 



Acetate of alumina 280 to 393 



Chloride of aluminium ... 540 



Phosphate of soda 311 



Carbonate of potash 439 



