48 
CHEMISTRY OF PEPSIN. 
In giving this outline of the action and chemical properties 
of pepsin with reference to the artificial preparation now 
found in commerce, 1 defer, in the absence of absolute proof 
to the contrary, to the statements of those physicians who 
have found its action beneficial, but at the same time cannot 
easily understand how such marked effects can be produced 
by the ingestion of so small doses of a substance which is 
secreted even in morbid conditions of the stomach in very 
large quantities. To take, for example, M. Boudault’s own 
statement, that fifteen grains of his pepsin, which is usually 
taken as the type of what the preparation should be, is 
capable of digesting sixty grains of dry fibrin. This simply 
amounts to saying that this quantity—the ordinary dose of 
the remedy—will digest 400 grains, or somewhat less than 
an ounce of beef muscle, and this almost homoeopathic addi¬ 
tion to a deficient secretion is recommended in the face 
of the fact, that were the whole quantity of gastric juice 
daily secreted by a healthy man expended upon the solution 
of bovine muscle, 14,000 grains, or thirty-two ounces, would 
be digested. 
The pepsin, or poudre nutrimentative, as it is called, of 
commerce, is a fawn-coloured powder, having somewhat the 
smell of glue, and in the ordinary lactic-acid combination a 
sour taste. 
The following tests for determining its purity have been 
given. The addition of a solution of acetate of lead should 
produce an abundant precipitate of peptate of lead ; a similar 
addition of a solution of tannin should precipitate tannate of 
pepsin, and alcohol added in excess should throw down the 
pepsin itself. Jn addition to these, if we are desirous of esti¬ 
mating its real value, the expenmentum crucis of testing its 
capability of digestion must never be neglected. For this 
purpose the pepsin is placed in distilled water at 60° Fahr., 
and the liquid filtered from the insoluble starch transferred to 
a small flask set in a water-bath, the temperature of which is 
maintained at 104° Fahr. The flask is closed with a cork, 
from which hangs a thread suspending a piece of coagulated 
white of egg or animal muscle. Matters being thus arranged, 
the fluid should soon attack and disintegrate the mass. The 
first evidence of its action will be observed when the sus¬ 
pended matter becomes covered with a gelatinous layer 
which soon dissolves, exposing a new surface to the influ¬ 
ence of the solvent. If the weight of nitrogenized mat¬ 
ter acted upon bear to the quantity of pepsin in the 
