ON PEPSINE. 193 
because it obstinately retains a certain quantity of acetic acid. 
A solution containing only T o Joo °^ pepsine, dissolves, in six 
or eight hours, the white of an egg slightly acidulated ; but 
it loses its digestive power when boiled, or when saturated 
with potassa. In the latter case it deposits flocculi, which are 
insoluble in water, and slightly soluble in dilute acids, form- 
ing liquors of feeble powers. 
Pepsine is recognised by forming, with acids, precipitates 
which are soluble in an excess of the acid. It is distinguished 
from albumen by the precipitates which acetic and hydro- 
chloric acid occasion in its aqueous solution; and from caseum, 
by the ferrocyanide of potassa not precipitating its acid solu- 
tions. 
A concentrated aqueous solution of pepsine is troubled by 
bichloride of mercury and acetate of lead, which form pre- 
cipitates, soluble in an excess of the reagent, and in the acetic 
and hydrochloric acids. The sulphate of the protoxide and 
sesquioxide of iron, and the chloride of tin, likewise precipi- 
tate pepsine, and all the precipitates formed with metallic solu- 
tions possess the digestive properties. ■ 
When burnt, pepsine gives off the odor of burnt horn, and 
leaves a charcoal, difficult to incinerate, in which is to be 
found lime, soda, phosphoric acid and some iron. 
Revue Scientif. et Indus t. — Journ. de Pharm. 
VOL. VI. — NO. III. 
25 
