138 CHEMICAL PHENOMENA OP DIGESTION. 
ART. XXXIX.— CHEMICAL PHENOMENA OF DIGESTION. 
BY MESSRS. BERNARD AND BARRISWILL. 
In a previous paper which we had the honor to submit 
to the judgment of the Academy, we experimentally proved 
that gastric juice is not limited merely to the dissolving of 
alimentary matters, but that it at the same time modifies 
them to an extreme degree, and thus prepares them for the 
ulterior phenomena of assimilation. 
This first fact once established, we proposed to ourselves 
to study the special mode of action which gastric juice ex- 
ercises upon the principal simple aliments. But before un- 
dertaking this study, it appeared to us indispensable to 
decide, definitely, upon the chemical constitution of the gas- 
tric juice, in the centre of which these transformations take 
place. 
The constant acid reaction which gastric juice presents, 
constitutes one of its essential properties ; it is known in 
fact, that gastric juice, neutralized by an alkali or an alka- 
line carbonate, loses entirely its digestive properties, which 
can always be restored by re-establishing its acid reaction. 
On another side we have acquired the certainty, that acidity 
is but one only of the elements of its activity — for, in expos- 
ing pure gastric juice to near the boiling temperature, it 
likewise loses its digestive properties, not from the absence 
of the acid re-action which remains the same, but by reason 
of your then acting upon another one of its principles which 
is essentially modified by heat. 
After these two principal facts we admit, saving further 
demonstration, that gastric juice is indebted for the whole 
of its activity to the union of two principles inseparable in 
their action — viz. : 1st. A substance with an acid re-action, 
