244 DIGESTION. 







the gastric juice. 1 It is chiefly on the last-named observa- 

 tions which have been supported by Bernard in his later 

 publications 2 and by the confirmatory experiments of Leh- 

 mann and others that those who admit the presence of free 

 lactic acid in quantity in the gastric juice rest their belief. 



We have already referred to the experiments of Bernard, 

 which show that an artificial fluid containing chloride of sodi- 

 um and lactic acid in solution behaves, during distillation, in 

 every way like the natural gastric juice. These show also how 

 hydrochloric acid may be produced during the last period 

 of the distillation by decomposition of the chlorides. We have 

 seen that this observation was confirmed by Lehmann, who 

 noted the same reaction during evaporation at the ordinary 

 temperature, in vacuo^ though he supposed the action in 

 the gastric juice to be upon the chloride of calcium instead 

 of the chloride of sodium. Lehmann found in the acid resi- 

 due, free lactic acid, lactate of lime, and alkaline chlorides. 

 Bernard and Lehmann have brought forward other experi- 

 mental facts to prove that the gastric juice contains lactic acid. 

 If starch be boiled in a solution containing hydrochloric 

 acid, it soon loses its property of forming a blue compound 

 with iodine ; while if it be boiled with lactic acid, no such 

 change is observed. If starch be boiled with a solution con- 

 taining hydrochloric acid, to which has been added a soluble 

 lactate in excess, it remains unaltered ; which shows, accord- 

 ing to Bernard, that hydrochloric acid in a free state cannot 

 exist in the presence of an excess of a salt of lactic acid. By 

 similar experiments, the same observer assumes to prove 

 that the existence of hydrochloric acid is inadmissible in the 

 presence of a phosphate or an acetate in excess. 3 Lehmann 

 has found that starch boiled with gastric juice retains the 

 property of being colored blue by iodine. 4 



1 Loc. cit. 



2 BERNARD, Legons de Physiologic Experimentale, Paris, 1856, p. 393 et seq. 



3 Op. cit., p. 398. 



* LEHMANN, Physiological Chemistry, Philadelphia, 1855, p. 93. 



