CHAP. II.] EARLIER RESEARCHES ON THE ACID OF GASTRIC JUICE. 91 



Prout's dis- In 1824 Dr Prout 1 published his investigations on 

 covery of the nature of the acid of the gastric juice, which were 



hydrochloric conducted upt)ri the watery solution of the acid con- 

 gastric juice 6 tents f tne stomachs of animals killed during diges- 

 tion, and upon acid vomited matters of man. Dr Prout 

 did not merely determine the acidity of these liquids by ascertaining 

 the amount of alkali required to neutralize them, but he shewed that 

 besides containing considerable quantities of chlorides, the acid con- 

 tents of the stomach contained hydrochloric acid which could be sepa- 

 rated by distillation. 



These observations were confirmed by Children 2 and by Bra- 

 connot 3 . Tiedemann and Gmelin 4 , though admitting that they had 

 in certain cases discovered hydrochloric acid in the contents of the 

 stomach, were of the opinion that Prout had been in error in con- 

 sidering it as the only acid present, as they had found both acetic 

 acid and butyric acid. 



Beaumont's observations on St Martin conclusively reconciled 

 the discrepant statements of previous observers by shewing that 

 whilst the gastric mucous membrane may have a neutral or alkaline 

 reaction during fasting, the gastric juice has invariably an acid taste 

 and acid reaction. An examination of the gastric juice made by 

 Professors Dunglison and Emmett 6 in 1833, confirmed Prout's state- 

 merit that, on distillation, gastric juice evolves hydrochloric acid. 



Lehmann's Prout had searched for lactic acid in the gastric 



discovery of juice, but had failed to find it. Lehmann, however, 

 lactic acid in arrived at a different result 6 , and he concluded that lactic 

 juice gastnc acid is really the normal acid of the gastric juice, and 

 that the hydrochloric acid found by Prout and others in 

 distilling the gastric juice was produced during the process of distilla- 

 tion by the action of free lactic acid upon the chlorides of the juice. 

 This view Lehmann subsequently modified, admitting the presence in 

 the gastric juice both of " free lactic acid and lactates, in addition to 

 free hydrochloric acid 7 ." 



Many observers, as Bernard and Barreswill 8 , Pelouse 9 and Dundas 



1 Prout, Philosophical Transactions, 1824, Part i. p. 45. 

 - Children, Annals of Philosophy, for July, 1824. 



3 Braconnot, Annales de Chimie, Vol. LIX. p. 348. 



4 Tiedemann u. Gmelin, Op. cit., Vol. i. p. 151. These authors discovered the 

 presence of hydrochloric acid in the gastric juice independently of Prout, as they inform 

 the reader in the Preface to their great work: 'Prout gebiihret die Ehre der ersten 

 Entdeckung. Aber wir haben sie ebenfalls unabhiiugig von ihm, im Februar 1824, 

 bei der Distillation verschiedener Magenfliissigkeiten entdeckt, und erst einen Monat 

 nachher kam uns seine Abhandlung iiber diesen Gegenstand zu Gesicht,' (Vol. i. 

 Preface, p. 12). 



5 Professor Dunglison's report is published in Beaumont's work, page 69. 



6 Lehmann, Bericht d. Gesellschaft der Wissenschaften zu Leipzig, Vol. i. 1847, 

 p. 100. 



7 Lehmann, Physiological Chemistry. Cavendish Society, 1851, Vol. i. p. 93. 



8 Claude Bernard, Lemons de Physiologic experimentale appliquee a la Medecine, 

 Vol. u. (1856). 



9 Pelouse, Comptes Rendus, Vol. xix. p. 1227. 



