PEPSIN. 



albumen is remarkable. Acidulated water, holding in solution 

 only O25 per cent, of pepsin, shows a decided action on albu- 

 men. 98 grains of water acidulated with muriatic acid, and con- 

 taining only 4-8 grains of the solution of pepsin, dissolves 49 

 grains of albumen in twenty-four hours at the temperature of 

 9 9. 5. Now as 4 '8 grains of the digesting liquor contain only 

 Oil grain of solid matter, it follows that one grain of pepsin is 

 capable of causing the solution of at least 100 grains of dry al- 

 bumen. 



11. When pepsin liquor is employed to dissolve albumen, it 

 partly loses its digestive power. Hence it must suffer an alte- 

 ration during the process. 



12. It acts best at the temperature of 100, but it will act also 

 at 54 or 55, though not so well. 



M. Wasmann has succeeded in obtaining pepsin in an isolated 

 state by the following process :* He separates the glandular 

 membrane of the stomach without cutting it, washes it, and 

 digests it in distilled water at a temperature between 86 

 and 95. After several hours, he decants off the liquid, and 

 washes the membrane again in cold water till it gives out a pu- 

 trid smell. The waters are mixed and filtered. The liquid thus 

 obtained is transparent, a little viscid, and possessed of a strong 

 digestive power, when a little muriatic acid is added to it. To 

 separate pure pepsin from it, acetate of lead is added, the pre- 

 cipitate washed, mixed with water, and decomposed by sulphu- 

 retted hydrogen. The liquid separated anew is fluid, colourless, 

 and acid. When, after having evaporated that liquid to the con- 

 sistence of a syrup, in a temperature which must not exceed 95, 

 we pour absolute alcohol into it, a copious flocky precipitate falls, 

 which, being carefully dried, is a yellow gum-like substance, which 

 does not attract moisture from the atmosphere. 



Pepsin is soluble in water, which it makes acid, because it re- 

 tains obstinately a little acetic acid. The solution, though it 

 contained no more than ^oo-th of pepsin, dissolves in six or eight 

 hours white of egg slightly acidulated : but it loses its digestive 

 properties when boiled or saturated with potash. In the last case, 

 it deposites flocks which are insoluble in water, but dissolve slow* 

 ly in dilute acids, constituting feebly digestive liquids. 



We recognize pepsin by the precipitates thrown down by di 



* Jour, de Pharm. xxvi. 481. 



