238 DIGESTION. 



they were then called) ; in another portion, the total amount 

 of hydrochloric acid, both free and combined ; and in another 

 the total amount of 'free acid. By this process, the estimate 

 for the free acid was corrected by subtracting the estimated 

 proportion of fixed acid from the proportion of acid, free and 

 combinecl. An abundance of hydrochloric acid was also in- 

 dicated by Prout in the acid matters vomited in certain cases 

 of dyspepsia. 1 



The method made use of by some of those who profess to 

 have found free hydrochloric acid in the gastric juice has 

 been to subject the fluid to distillation, testing the acid fluid 

 which passes over, with nitrate of silver. This was the 

 method employed by Dunglison and Emmet ; 2 but the 

 experiments of Bernard and Barreswil on the gastric juice 

 from dogs, and the more recent observations of Dr. F. G. 

 Smith on the gastric juice from St. Martin, have shown that 

 this process is really of little value. The following observa- 

 tions by Bernard and Barreswil show conclusively that al- 

 though hydrochloric acid may be obtained from gastric juice 

 by distillation, it does not necessarily exist in the fluid in a 

 free state ; a very important consideration in a question in 

 which every thing depends upon the absolute accuracy of 

 modes of analyses : 



In subjecting the gastric juice of the dog to distillation 

 at a low temperature, with all the necessary precautions, it 

 was found that the first products did not present an acid re- 

 action. It was at first thought that this would be ground 

 for the exclusion of hydrochloric acid, which is considered to 

 be volatile ; but it was found that in the distillation of water 

 which had been slightly acidulated with hydrochloric acid, 

 the first products were neutral, and the acid was only disen- 

 gaged in the fluid which passed over toward the last periods 



1 PROUT, On the Nature of the Acid and Saline Matters usually -existing in the 

 Stomaclis of Animals ; read Dec. 11, 1823. Philosophical Transactions, London, 

 1824, p. 45 et seq. 



2 BEAUMONT, op. cit., p. 78. 



