402 LIQUID PARTS OF ANIMALS. 



only 4^th of its weight of pepsin shows a decided action on al- 

 bumen. 98 grains of water acidulated with muriatic acid, and 

 containing only 4-8 grains of the solution of pepsin, dissolve 49 

 grains of albumen in twenty-four hours, when kept at the tem- 

 perature of 99.5. Now, as 4'8 grains of digesting liquor con- 

 tain only 0-11 grain of solid matter, while 49 grains of albumen, 

 when dried, leave about 10 grains of solid matter, it follows that 

 one grain of pepsin is capable of causing the solution of 100 

 grains of dry albumen. 



When pepsin liquor is employed to dissolve albumen, it part- 

 ly loses its digesting power. Hence it must suffer an alteration 

 during the process. 



It acts best at the temperature of 100. But it will act also 

 at 54 or 55, though not so well. 



When the albumen has been previously reduced to a fine 

 powder, it is dissolved in from six to twenty-four hours. Fi- 

 brin is dissolved in from three to twelve hours. The presence 

 of atmospherical air is not necessary for these solutions, and no 

 gas is given out. Some salts, sulphate of soda, for example, hin- 

 der the digesting action of pepsin. 



The solution of albumen in the pepsin liquor consists, accord- 

 ing to Schwann, of, 1. Altered albumen dissolved in the acid, 

 and precipitable by neutralizing that acid ; 2. Of osmazome ; 

 3. Of salivin. Flesh, both raw and roasted, is also dissolved by 

 the pepsin liquor ; but the process is slower.* 



Vogel has shown that pepsin is not formed by the action of 

 the acid upon the mucous membrane of the stomach. For if 

 we digest the mucous membrane in pure water we obtain a li- 

 quor which possesses digestive properties. Other acids produce 

 the same effect as the muriatic. Vogel tried the sulphuric, ace- 

 tic, phosphoric, and nitric acids successfully. Phosphoric acid 

 answered best, and nitric acid worst of all these acids.f 



Vogel examined also the changes produced upon albumen and 

 fibrin when dissolved in the pepsin liquor. It had been shown 

 by Eberle and Schwann, that the albumen, after being so dis- 

 solved, was not coagulated by heat, and was partly soluble in al- 

 cohol. The solution is muddy. Alcohol increases the muddi- 

 ness somewhat, Tannin throws down an abundant brownish- 



* Schwann, Poggendorfs Annalen, xxxviii. 358. 

 t Jour, de Pharmacie, xxv. 648. 



