4 6 Dr. Prout on the nature of the acid and saline matters 
its origin and use ; some supposing that it is derived from 
the stomach itself, and is essential to the digestive process ; 
others, that it is derived from the food, or is a result of fer- 
mentation, &c. ; in short, there seems to be no physiological 
subject so imperfectly understood, or concerning which there 
has been such a variety of opinions. 
The object of the present communication is to show, that 
the acid in question is the muriatic acid , and that the salts 
usually met with in the stomach, are the alkaline muriates. 
As to the origin and use of these principles, as well as the 
occasional appearance of other acids, &c. in the stomach, I 
reserve what I have to say on these subjects till a future 
opportunity, and shall merely remark at present, that the 
facts now adduced seem to be intimately connected, not only 
with the physiology and pathology of the digestive process, 
but with other important animal functions. 
Having ascertained the circumstances above mentioned in a 
general manner, and by means which it would be here un- 
necessary to detail, an attempt was made to contrive some 
unexceptionable method by which their truth might not only 
be satisfactorily demonstrated, but at the same time that the 
relative quantities of the different principles might be deter- 
mined : after various attempts, the following processes were 
adopted for these purposes. 
The contents of the stomach of a rabbit, fed on its natural 
food, were removed immediately after death, and repeatedly 
digested in cold distilled water till they ceased to impart any 
thing to that fluid. The whole of these different portions of 
fluid, which always exhibited strong and decided marks of 
acidity, were then intimately mixed together, and after being 
