112 HALT'S VIEWS. [BOOK u. 



phosphate coexists in solution with sodium chloride, free hydro- 

 chloric acid is set free, as shewn in the following equation : 



NaH 2 P0 4 + NaCl = Na 2 HP0 4 + HC1. 



As a fact, all four bodies will exist side by side during the reaction. 



But not only is HC1 formed by the interaction of dihydrogen 

 sodium phosphate on chlorides, but likewise by the action of calcium 

 chloride on hydrogen disodium phosphate, as shewn in the following 

 equation : 



SCaCl, + 2Na 2 HP0 4 = Ca 3 (P0 4 ) 2 + 4NaCl + 2HC1. 



Maly thus believes that by the interaction of carbonic acid, 

 disodic phosphate, monosodic phosphate, and sodic and lactic chlo- 

 rides, hydrochloric acid is set free in the blood. But this acid 

 possesses a higher diffusive power than any other acid, and we 

 have only to surmise that the glands of the stomach are diffusion 

 apparatuses of remarkable power in order to account for the separa- 

 tion of hydrochloric acid by them. 



Objections to It is impossible not to appreciate the great value 

 Maiy's theory. of the fectg upon which Maly restg ki s theory, and 



not to acknowledge that he has thrown great light upon the 

 part which diffusion may play in separating, from the alkaline 

 blood, acids or acid salts which are present in it, although their 

 reaction may be concealed by that of such salts as alkaline sodium 

 phosphate. If, however, the reaction which results in the production 

 of hydrochloric acid is one which goes on throughout the whole mass 

 of the blood, and its separation occurs through a mere process of 

 diffusion, we cannot but ask ourselves how it is that the acid only 

 diffuses into the gastric juice, and not into the secretions of other 

 glands which, as apparatuses of diffusion, offer obviously as favourable 

 conditions as the stomach. 



Why for instance does hydrochloric acid not pass into the urine ? 

 and unquestionably no trace whatever of any free mineral acid 

 occurs in that secretion. Maly would meet the difficulty by at- 

 tributing particular powers to the different glands as dialyzing appara- 

 tuses, but then we lose all the value of the physical explanations 

 which appeared at first to be so likely to explain the phenomena. 



Against the views of Maly there appear to be two capital objec- 

 tions. The first has reference to the chemical process which he 

 supposes to occur in the blood, and to result in the liberation of 

 free hydrochloric acid, and the second to the view that the glands of 

 the stomach are from one point of view but apparatuses of diffusion 

 which allow the hydrochloric acid of the blood to escape from it into 

 the gastric juice. 



Firstly We can readily admit that there may coexist in the 

 blood, acid and alkaline sodium phosphates and common salt, and 

 that by the reaction of the latter on the former traces of hydrochloric 



