Capillary Attraction. 461 



solutions of gum and sugar were tried, the endosmose took 

 place from the gum to the sugar, even when the former 

 was twice as much concentrated as the latter. Many acids, 

 as nitric, muriatic, phosphoric, and acetic, when they are 

 separated from water, by an animal membrane, receive the 

 endosmose from the latter. Concentrated sulphuric acid 

 destroys the membrane ; and when diluted, exhibits no 

 si°ns of endosmose. When oxalic acid and water are em- 

 ployed, the endosmose proceeds from the acid to the wa- 

 ter, and increases in proportion to the strength of the so- 

 lution. By itself, however, oxalic acid passes more slowly 

 through animal membrane than water. When a solution 

 of tartaric acid exceeds the specific of 1*05, the endosmose 

 takes place from the water to the acid ; if it is lighter than 

 1-05, the process is reversed. The same happens with 

 citric acid. 



Dutrochet terms the passage of the oxalic acid to the 

 water, inverse endosmose. The mineral acids do not 

 exhibit this phenomenon ; phosphoric acid, however, ex- 

 hibits it for an instant, when reduced by the addition of 

 water, to the specific gravity of 1*085. Change of tempe- 

 rature affects the passage of the acid through the mem- 

 brane, as it does its specific gravity. 



This agrees with the experiments of Girard, upon the 

 flowing of pure water, and water containing Nitrate of 

 potash, through capillary glass tubes. A solution of one 

 part nitrate of potash in three parts water, at the tempe- 

 rature of 40°, flows more readily through a capillary tube 

 than pure water ; while above 40°, the reverse happens. 

 Dutrochet has found these observations to hold only with 

 animal membranes ; not with vegetable, or thin inorganic 

 porous plates. — (Pharmaceutisches Central-blatt., Feb. 1836, 

 92.) 



2. Jerichau ,* of Copenhagen , has obtained some interesting 

 results on this subject. A forked glass tube, 1J line in dia- 

 meter, was closed at one extremity with sealing wax, and 

 then the closed leg was filled with water, the covered por- 

 tion with mercury, and the open leg partly with an aque- 

 ous solution of sugar. The tube was placed in a vertical 

 position. 



• Poggendorff'a Annaleii, xxxiv. 613. 



