228 ANNUAL OF SCIENTIFIC DISCOVERY. 



an acid condition of the outer surface, the favorable condition of a high 

 positive osmose. The bibasic salts of potash and soda again, such as the 

 sulphate and tartrate of potash, although strictly neutral in properties, 

 begin to exhibit a positive osmose, in consequence, it may be presumed, 

 of therrresolutioii into an acid supersalt and free alkaline base. 



It may appear to some that the chemical character which has been, 

 assigned to osmose takes away from the physiological interest of the sub- 

 ject in so far as the decomposition of the membrane may appear to be 

 incompatible with vital conditions, and that osmotic movements must 

 therefore be confined to dead matter; but such apprehensions are, it is 

 believed, groundless, or at all events premature. All parts of living struc- 

 tures are allowed to be in a -state of incessant change of decomposition and 

 renewal. The decomposition occurring in a living membrane while effect- 

 ing osmotic propulsion may possibly, therefore, be of a reparable kind. In 

 other respects chemical osmose appears to be an agency particularly 

 adapted to take part in the animal economy. It is seen that osmose is 

 peculiarly excited by dilute saline solutions, such as the animal juices 

 really are, and that the alkaline or acid property which these juices 

 always possess is another most favorable condition for their action on 

 membrane. The natural excitation of osmose in the substance of the 

 membranes or cell- walls dividing such solutions seems, therefore, almost 

 inevitable. In osmose there is, further, a remarkably direct substitution 

 of one of the great forces of Nature by its equivalent in another force the 

 conversion, as it may be said, of chemical affinity into mechanical power. 

 Now, what is more wanted in the theory of animal functions than a mech- 

 anism for obtaining motive power from chemical decomposition as it occurs 

 in the tissues ? In minute microscopic cells, the osmotic movements, being 

 entirely dependent upon extent of surface, may attain the highest con- 

 ceivable velocity. May it not be hoped therefore to find, in the osmotic 

 injection of fluids, the deficient link which certainly intervenes between 

 muscular movement and chemical decomposition ? 



/ 



ON THE CONCENTRATION OF ALCOHOL IN SOMMERING's EXPER- 

 IMENTS. 



Prof. Graham, before the British Association, stated that, when an open 

 vessel is filled with a mixture of alcohol and water and exposed to the air, 

 the alcohol goes off first and leaves the water ; but if, as in Sommering's 

 experiments, a bladder be completely filled with dilute alcohol, the liquid 

 will decrease in bulk, and the water pass through the membrane, leaving 

 a much larger percentage of alcohol in the bladder. Dry membrane does 

 not exhibit this phenomenon ; for a jar, the mouth of which is covered 

 with dry bladder, allows the alcohol to escape first. The author believed 

 that liquids diffuse mechanically, by a kind of repulsive force of the same 

 nature as that exhibited by gases. When common salt is added to water 

 in a jar, membrane tied over it, and immersed in a vessel containing pure 



