132 RINDERPEST. 



degrees of manifestation, and do not all deport themselves as 

 pure chemical solvents. In some cases they can hardly be 

 said to exert any direct, if any influence whatever, on the 

 fermenting fluid. Take, for instance, arsenious acid (com- 

 mon arsenic). Its action is wholly confined to the mem- 

 branes and membranous tissues with which it is brought in 

 contact. It does not exert the slightest influence, according to 

 Liebig,* on the fermentation of sugar in vegetable juices, 

 the action of yeast on sugar, or even the putrefaction of the 

 blood ; its scope of action on the tissues being explained by 

 the fact that the gelatinous tissues form a combination with 

 this acid, similar to that which tannic acid forms with the 

 skin. The prudential use to be made of this discovery of 

 the chemist, and as corroborating what has been previously 

 advanced (p. 110), is that this acid has no relation to the 

 Pest; and that neither this nor any other acid should be 

 employed in the treatment of any zymotic, whose force is 

 expended in part or in whole on the membranes with which 

 it is brought in contact, unless it has the further peculiarity 

 of ensuring for, or restoring to them a more active power of 

 absorption. 



But a more pertinent illustration is to be drawn from the 

 behavior of common salt in the phenomena first observed by 

 Butrochet, when exploring the mutual action of two liquids 

 on each other through a membrane. This action was named 

 by him and is now generally known as endosmose, 

 • If a glass tube about six inches long and with an aper- 

 ture of one-quarter of an inch, be covered at one end with a 

 piece of fresh membrane, taken from an intestine, bladder or 

 stomach ; and after being filled with a solution of salt, is held 

 in a vessel containing pure water, so that the level of the two 

 fluids is the same : in a short time there will be perceived 

 an elevation of that contained in the tube, which is to be 

 regarded as the result of a force exerted against the law of 

 gravitation, and at its height is equivalent to and may be 

 measured by a column of mercury two or three inches in 

 height. 



 Animal Chcmletry, p. 186. 



