CHAP. II.] ' COEFFICIENT DE PART AGE ' OF ACIDS. 97 



By adopting a new method; to be immediately referred to, he 

 proved also more satisfactorily than had ever been done before, 

 that fresh gastric juice owes * its acidity to a single acid, though 

 after the gastric juice has been kept for some time it undergoes 

 decompositions which lead to the appearance of more than one acid. 

 Richet has however been led to the conclusion that the chlorine- 

 containing acid of the gastric juice is not free hydrochloric acid, but 

 an acid conjugated with leucine. 



Bertneiot's J n endeavouring to decide the question whether 



method of de- t k e pr as ^ r i c i u i ce contains a mixture of acids or one 

 termining the . a , -,-> , J . ,111-11 



nature of acids acit * on v > Richet made use ot a method devised by 

 in solution by Berth elot, which will doubtless be of much use in 

 their 'coeffl- future researches in physiological chemistry. 



The method rests upon the following principles : 

 When a watery solution of an acid is shaken up with 

 an equal volume of pure ether, the latter fluid takes up a certain 

 proportion of the acid, which varies with the nature of the acid 

 and with the temperature. The ratio of the amount of acid con- 

 tained in the ether to that remaining in the water is therefore con- 

 stant for each acid at a given temperature ; by dividing the number 

 expressing the acidity of the water (expressed for instance in terms 

 of a standard alkaline solution used) by the number expressing the 

 acidity of the ether, we obtain as a quotient the "coefficient de 

 partage " of Berthelot, which we may term the "coefficient of repar- 

 tition " or, perhaps better, ' coefficient of distribution.' In the case of 

 mineral acids, the amounts dissolved by the ether are very small, and 

 the coefficients are represented by high numbers; in the case of the 

 organic acids, the amount soluble in ether is large, and the coefficients 

 are small numbers. 



The following are the " coefficients of repartition" of some organic 

 acids : 



Lactic acid C= 8'8 ll'O 



Succinic C= 6'0 



Benzoic C= 9'5 



Acetic C= 1*4 



Tartaric C = 96'0 



When two or more acids are, however, present in a watery solu- 

 tion, the determination of the coefficient of each is also a possible, 

 though necessarily a more complex, operation. 



By employing this method, Richet found that perfectly fresh 

 gastric juice contains essentially one acid with a very high coefficient 

 of distribution an acid, that is, which, as the mineral acids, is 

 almost insoluble in ether. 



1 Ch. Richet, Le Sue Gastrique chez Vhomme et les Animaux, sea proprietes Chimiques 

 et Physiologiques. Paris, 1878. 



G. 



