3 5 2 CHEMISTR Y OF THE DIGESTIVE PR O CESSES. 
end of the process hydrochloric acid passes over. In addition, he tried 
to obtain lactic acid from gastric jnice, but with negative results. 
The remarkable results so obtained by Prout were confirmed by- 
Children 1 in England, by Braconnot 2 in France, and by Dimglison 
and Emmet, 3 with gastric juice obtained from Beaumont's case of 
fistula. 
When the period at which they were carried out is considered, it 
must be admitted that these experiments of Prout were most ingenious, 
and he well deserves the honour of being the first to awaken the minds 
of men to the conception that the animal organism was capable of 
producing such a substance as hydrochloric acid. 4 Physiological chemists, 
however, were chary in believing that the gentler forces of the animal 
organism were capable of producing such a substance as hydrochloric 
acid, which they were unable to obtain experimentally except by the 
use of potent inorganic reagents. Accordingly, objections flowed in 
against Prout's work. 
Claude Bernard and Barreswil 5 showed that when sodium chloride 
was added to a solution of lactic acid, and the mixture distilled, hydro- 
chloric acid appeared in the distillate towards the end of the process 
when the mixture was beginning to grow solid. They concluded that the 
free acid of the gastric juice was lactic acid. Lehmann 6 ascribed the 
free hydrochloric acid of Prout's distillation experiment to the action of 
the lactic acid, concentrated by evaporation, on the calcium chloride also 
present in gastric juice. Many other observers were also agreed that 
the free acid in gastric juice was lactic acid. 7 Blondlot 8 about this time 
enunciated the hypothesis that the acidity of the gastric juice was due 
in part to acid calcium phosphate, and evolved a theory, closely 
resembling a much more recent one by Maly, as to the origin of the 
acid by the formation of this substance, accompanied by traces of hydro- 
chloric and phosphoric acids in the stomach wall, from the sodium 
chloride and calcium phosphate of the blood. 9 In presence of hydro- 
chloric acid it is now known that part of any calcium phosphate present 
would be resolved into acid phosphates, but the amount of calcium 
phosphate present in gastric juice is altogether insufficient to account for 
any appreciable part of its acidity. 
While the subject was still in this vexed condition, Bidder and 
Schmidt's 10 classical work on digestion appeared, containing the results 
of Schmidt's experiments, to which reference has already been made. As 
1 Annals of Philosophy, Jul}' 1824. 
2 Ann. de chim., Paris.. 1835, tome lix. p. 348. 
3 Published with Beaumont's results, 1S34. 
4 As is often the case in great discoveries, Prout seems not to have been much in time 
ahead of his fellows. Tiedemann and Gmelin state in the preface to their classical work, 
" Die Verdauung nach Versuchen," 1826 (while admitting Prout's priority), that independ- 
ently they had found hydrochloric acid in distilling various gastric fluids, and a month 
later first saw Prout's publication. However, Prout was clearly ahead of them, both in the 
distillation method, and in its ingenious confirmation by analytical results, as described in 
the text. 
5 Compt. rend. Acad. d. sc, Paris, 1844-5 ; "Lecons de physiol. exper. applique a la 
med.." 1856, tome ii. p. 397. 
6 Ber. d. Sachs. Gesellsch. d. Wissensch., Leipzig, 1847. 
7 Pelouse, Compt. rend. Acad. d. sc, Paris, tome xix. p. 1227 ; Thomson, Lond. 
Edin. and Dub. Phil. Mag., London, 1845. 
8 "Traite analytique de la digestion," 1843; Jahresb. u. d. Fortschr. d. ges. Med., 
Erlangen, 1851, Bd. i. S. 97 : 1858, Bd. i. S. 37. 
9 See p. 361. 
10 "Die Verdauungssafte und der Stoffwechsel," Mitao u, Leipzig, 1852, S. 44. 
