. III. VELOCITY OF THE CURRENT. 47 



Increase of temperature augments the rapidity of the cur- 

 rent of endosmose. 



Dutrochet found that the slightest trace of sulphuretted 

 hydrogen destroyed endosmose. It is probable, however,, 

 that this effect arose from the alteration in the condition, 

 of the membrane when it commences to evolve this gas ; 

 for fresh membrane placed in contact with sulphuretted hy- 

 drogen is very active. 



Velocity of the Current. Dutrochet endeavoured to 

 measure the velocity with which a liquid passes, by virtue 

 of endosmose, from the exterior to the interior of the tube. 

 Here are the results of his experiments : With a mem- 

 brane of 40 millimetres in diameter, and a tube of 2 milli- 

 metres, a solution of sugar, whose density was 1-145 rose 

 34 divisions in the space of an hour and a half; each 

 division being 2 millimetres. In another experiment, he 

 employed a solution of sugar, the density of which was 

 1-228, and the ascent in the same space of time was 53 

 divisions. Lastly, in a third experiment, with a solution 

 of sugar of the density of 1-083, the column mounted 19 \ 

 divisions in the same interval of time. It is evident, 

 therefore, that the velocity of endosmose is proportional 

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

 the water employed as the exterior liquid. 



Dutrochet took different solutions having the same densi- 

 ty, and compared them with water, from which they were 

 separated by bladder. 



The following ratios express the variable intensity of en- 

 dosmose obtained in the different cases : 



