242 DIGESTION. 



a precipitate of the insoluble oxalate of lime, which does not 

 take place in the presence of free hydrochloric acid, even when 

 it exists in very minute quantity. ISTo one has denied that this 

 reaction always takes place in the gastric juice ; but, in this 

 fluid, is it inconsistent with the presence of a small quantity 

 of hydrochloric acid ? We have found that the addition of 

 two drops of ordinary hydrochloric acid to half a fluid ounce 

 of gastric juice does not prevent the precipitation of the oxa- 

 late of lime, which, in the single observation referred to, 

 was only prevented when the quantity of acid was increased 

 to five drops. On adding oxalic acid to fresh urine, the 

 precipitate of oxalate of lime was marked ; but after the 

 addition of two drops of ordinary hydrochloric acid, this re- 

 action did not take place. Taken in connection with the 

 fact that many of the ordinary chemical reactions are pre- 

 vented or modified in fluids containing organic substances, 

 this would lead us to inquire whether free hydrochloric acid 

 may not exist in small quantity in the gastric juice, and, as 

 an exceptional phenomenon, the reaction between the oxalic 

 acid and the soluble salts of lime still take place ; or whether 

 the acid may not unite with the organic principle, forming, 

 as was suggested by Schiff, chlorohydropeptic acid. In 

 support of this latter view, it is to be remembered that Mul- 

 der has formed combinations of organic principles with vari- 

 ous of the mineral acids, such as the sulphuric and the hy- 

 drochloric. In these compounds, the acid character remains, 

 but the ordinary reactions of the acid are lost. For exam- 

 ple, in a compound of sulphuric acid, called by Mulder, sul- 

 pho-proteic acid, the precipitations with baryta and lime do 

 not take place. 1 



1 These compounds of mineral acids with organic principles have been very 

 little studied. In view of the accurate researches of Bidder and Schmidt, and 

 the fact that many of the properties of fluids containing free hydrochloric acid 

 are wanting in the gastric juice, Longet, after a full and candid discussion of the 

 whole question, admits the possible existence of an acid compound of pepsin and 

 hydrochloric acid, characteristic of the gastric juice ; but he contends for the 

 existence, in addition, of a certain proportion of a free organic acid, which he 



