98 RICHET'S RESEARCHES. [BOOK n. 



How valuable the method is in establishing that lactic acid 

 could not be the cause of the acidity of the gastric juice is shewn 

 by the following experiment : 



Pure gastric juice was shaken with ether and the acidity of the acid 

 and ether afterwards determined. The coefficient of repartition was found 

 to be 137'1, i.e. the amount of acid held in solution by the water was 

 137'1 times greater than that held in solution by an equal volume of 

 ether. A certain quantity of the same gastric juice was now treated with 

 solution of barium lactate. By the action of the HC1 of the juice upon 

 this salt there would obviously be set free au equivalent quantity of lactic 

 acid, which should now be the free acid of the juice. The coefficient of 

 repartition was now determined and found to be 9 '9, i.e. that of lactic 

 acid. 



When the gastric juice is kept, however, as well as during the 

 process of digestion, there are formed other acids, such as lactic, 

 butyric, and acetic, the occurrence of which will be again referred 

 to, in discussing the changes which go on in the stomach during 

 digestion. 



Although Richet concludes from his researches that the gastric 

 juice, when fresh, contains but one acid, and that a chlorine-containing 

 mineral acid, he is led by an experiment now to be referred to, 

 to the opinion that this is not free hydrochloric acid. 



Hydrochloric acid is so slightly soluble in ether that it does not 

 possess an appreciable coefficient of repartition. If however, as 

 M. Berthelot shewed, an alkaline acetate is added to dilute hydro- 

 chloric acid, acetic acid is set free and a chloride formed ; if then we 

 shake the mixture with ether we obtain a number which is essen- 

 tially the coefficient of repartition of acetic acid. On trying this 

 experiment with gastric juice, Richet did not however obtain a 

 coefficient low enough for acetic acid ; it was from 5 to 5 '8 instead 

 of 1*7. This fact Richet explains by saying that the quantity of 

 acetic acid set free by the gastric juice was to that which hy- 

 drochloric acid would have set free as 0'4 to 1, and from this he 

 concludes that the acid of the gastric juice cannot be free hydro- 

 chloric acid. 



Richet further has found that by digesting at 45 dilute hydro- 

 chloric acid with the mucous membrane of the fourth stomach of a 

 calf, a solution is obtained which behaves in respect to acetate of soda 

 exactly like gastric juice. Upon grounds which appear to the author 

 very slender, and the chief of which is that he has, as Klihne has done 

 long ago, succeeded in separating traces of leucine from the mucous 

 membrane of the stomach, Richet believes that there is formed in 

 this case, a conjugate acid of leucine and hydrochloric acid, and that 

 such a conjugate acid is the normal acid of the gastric juice. The 

 author in conjunction with Dr Haslam has prepared hydrochlorate of 

 leucine and finds that the salt does not in relation to pepsin act as an 

 acid, i.e. that when pepsin is mixed with a watery solution of the 

 compound of hydrochloric acid and leucine, and the mixture is heated 



