48 ENDOSMOSE. L.ECT. III. 



Intensity of Endosmose of various Liquids with Water. 



(Dutrochet.) 



Solution of gelatine ... . 3 



" gum .... 5-17 



" sugar 11 



" albumen - ... 12. 



From this table we see, that of all organic substances 

 soluble in water, albumen produces endosmose with the 

 greatest force. 



Direction of the Current Among the most curious facts 

 discovered by Dutrochet, while studying endosmose, must 

 be mentioned that of the variation in the direction of the cur- 

 rent between certain acid solutions and water, according 

 to their density and temperature. This is especially mani- 

 fested by a solution of hydrochloric acid. Thus, with hy- 

 drochloric acid at the density of 1-02, endosmose takes 

 place from the \vater to the acid, whilst at the density of 

 1-015, the current is in the opposite direction; that is to 

 say, it is from the acid to the water. 



Force of the Current. Dutrochet endeavoured to deter- 

 mine the amount of pressure exercised by the column of 

 liquid elevated by endosmose in the different cases. For 

 this purpose he employed the apparatus which Hales first ? 

 and afterwards Mirbel and Chevreul, used for measuring 

 the pressure of the juices in plants. In this apparatus the 

 pressure is estimated by the height of a column of mercury 

 raised by the liquid. 



In studying endosmose under this point of view, Du- 

 trochet proved that, all other things being equal, the force, 

 which produces the current of endosmose, is proportional 

 to the excess of the density of the interior liquid over that 

 of the water. We have already seen that the velocity of 

 endosmose likewise varies. It, therefore, follows, that 



