1?26.] l)r, Proui on Digestion, ^% 



t|je case* My object in publishing the paper in question wa^ 

 simply tp establish that one important fact, and nothing 

 more; though I confess I then believed, and do still, that 

 the muriatic acid occurs naturally more frequently, and in 

 greater abundance, in that organ than any other acid: for 

 >vhen I have met with combustible acids (as I have, since 

 jny paper was published, in a few instances), these seemed to 

 be rather derived from the food than from the stomach itself, in 

 jnost instances. So far, however, am I from denying the exist- 

 ence of any other acid in the stomach except the muriatic, that 

 on the contrary I think it exceedingly probable, were the con^ 

 tents of the human stomach in particular examined, under 

 all the circumstances of diet and derangement to which it is 

 liable, that many other acids besides the acetic and butyric (of 

 which latter, by the bye, I know nothing) would be found in it. 

 With respect to the lactic acid which has so long figured as an 

 important ingiredient in animal fluids, chiefly on the authority 

 of Berzehus, I always doubted its existence, and am not there- 

 fore at all surprised that it has proved to be a nonentity. MM. 

 Tiedeman and Gmelin inform us,* that Berzelius himself now 

 admits that he was mistaken, and that in fact what he con^ 

 sidered as lactic acid is only disguised acetic acid. I long tp 

 §ee the grounds on which this justly celebrated chemist has 

 changed his opinion. 



MM. Tiedeman and Gmelin make some remarks on the 

 vjnethod I employed for determining the nature and quantity of 

 acid in the stomach which require to be noticed. This method, 

 to a certain extent, they give very accurately, but omit entirely 

 the point of most importance,andwhichwas designed as a check npon 

 the whole ; and then proceed to say that the method is inexact 

 and imperfect. To render this obvious, it will be neces- 

 sary to repeat the method here, which was as follows : The fluid 

 collected from the stomach was divided into four portions. 

 " 1. The first of these portions was evaporated to dryness in its 

 jiatural state, and the residuum burnt in a platinum vessel; the 

 saline matter left was then dissolved in water, and the quantity 

 of muriatic acid present determined by nitrate of silver in the 

 usual manner ; the proportion of muriatic acid in union with a 

 fi:x:ed alkali was thus determined. 2. Another portion of the 

 original fluid was supersaturated with potash, then evaporated 

 to dryness and burnt, and the muriatic acid contained in the 

 saline residuum determined as before. In this manner the total 

 quantity of muriatic acid present in the fluid was ascertained. 

 3. A third portion was exactly neutralized with a solution of 

 potash of known strength, and the quantity required for that pur- 

 pose accurately noticed. This gave the proportion oi'free acid 

 present; and by adding this to the quantity in union with ^ 



# Pasgp 167. 



