STOMACH AND INTESTINE. 



331 



residuum, or found in the distilment, of the 

 gastric juice they * brought forward the 

 fact, that towards the close of the process of 

 distillation, the fixed lactic acid was capable 

 of displacing the volatile hydrochloric from 

 the salts in which it had been formerly com. 

 bined ; leaving lactates and lactic acid, in a 

 thick acidulous residue of a syrupy consistence. 

 They added, that this late appearance in dis- 

 tillation (as shown by nitrate of silver and 

 peroxide of manganese) proves the absence 

 of the free acid ; as does also the precipitate 

 effected in gastric juice by oxalic acid, a 

 precipitate which would not occur in water 

 containing but s^th of hydrochloric acid. 



To this one might have answered, that 

 such a displacement of hydrochloric acid 

 could scarcely have occurred in any of these 

 analyses. Dr. Prout examined in vain for 

 organic acids. And just as he expressly af- 

 firms, so others imply, their absence. While 

 Dunglison -j- and Berzelius found that the re- 

 siduum contained a large quantity of chlorides. 

 And if it be difficult to suppose the chlorides 

 of the gastric juice sufficient, both for a large 

 distilment of acid, and a still larger residuum 

 of salts, it is even more difficult to imagine 

 (with Lehmann J), that the chloride of cal- 

 cium alone can yield the former, and yet also 

 appear in the latter. 



The absence of the ordinary reactions of 

 hydrochloric acid is, indeed, explained by a 

 theory of Schmidt's, which will be noticed 

 again hereafter, and according to which the 

 acid is in some degree fixed and retained by its 

 chemical combination with the organic prin- 

 ciple of the gastric juice. He shows that, if 

 a solution of nitrate of silver be added to this 

 secretion, it throws down a precipitate, which 

 consists of chloride and organic matters; 

 while conversely, it leaves some silver in the 

 clear supernatant fluid. But such a fact 

 scarcely requires the aid of the above theory. 

 The way in which the affinity of even small 

 quantities of organic substances can disturb 

 various chemical processes, offers a well- 

 known analogy to this retarded precipitation. 

 And without some such an action really ob- 



hyolrochloric acid, as well free as combined. The 

 third method would allow of the estimate of the 

 free acid. And this, together, with the fixed hydro- 

 chlorates of the first method, subtracted from the 

 total of the second, would leave the quantity com- 

 bined with the volatile alkali ammonia. He thus 

 found, that rather more than half the chlorine 

 present was combined with hydrogen, in the form 

 of free hydrochloric acid, while, of the remainder, 

 nearly half was united with ammonia, the rest with 

 potassium and sodium. A fourth portion was exa- 

 mined in vain for an organic acid. And other salts, 

 uch as sulphates and phosphates, were only found 

 in very small quantity. 



* Aided and confirmed by the observations of 

 Blondlot (Loc. *.), Huenefeld (Chemismus in der 

 Thierischen Organization, Leipzig, 1840, p. 207. et 

 *eg.), and others. 



t With the " astonishing quantity " of chloride 

 of silver obtained from the distilled liquid by Dun- 

 glison, there ought to have been at least half as 

 much lactic acid in the (apparently uninjured) re- 

 siduum. 



t Compare Op. cit. vol. i. p. 98. and vol. ii. p. 43. 



tained, the non-precipitation of dissolved albu- 

 men by gastric juice would (as Blondlot 

 indeed assumes) disprove the presence of 

 both lactic and hydrochloric acids in this fluid. 



The analysis of Enderlin, however, carried 

 the investigation a step further, by distinctly 

 asserting the presence of hydrochloric acid in 

 the residuum of the distillation.* And Bid- 

 der and Schmidt's recent experiments seem 

 quite conclusive, both as to the presence of 

 this, and the absence of lactic, acid.-f- These 

 observers avoid distillation, and treat the fresh 

 gastric juice, previously acidulated by nitric 

 acid, with nitrate of silver ; so that the pre- 

 cipitate is free from all organic matters. To 

 the supernatant liquid, they add hydrochloric 

 acid, so as to remove all excess of silver ; and 

 then determine its bases by evaporation and 

 ignition. These they find insufficient to neu- 

 tralize the chlorine of the precipitated chlo- 

 ride. And on saturating a quantity of the 

 same juice with potash, baryta, or lime, they 

 find that the amount required for its neutrali- 

 zation is exactly equivalent to the deficiency 

 observed in che previous analysis. 



But this leaves us with two gastric acids, 

 the hydrochloric and the lactic. Hence three 

 questions suggest themselves. (1.) Are 

 they present together ? (2.) Do they substi- 

 tute or replace each other? Or (3.) is the 

 lactic acid a mere secondary and accidental 

 product ? 



Even since Bidder and Schmidt's analyses, 

 Lehmann has again answered the first of these 

 questions in the affirmative ; having found 

 both acids together in a quantity of gastric 

 juice collected from 14 dogs. The second 

 and third questions cannot at present be re- 

 plied to. As regards the second, we have 

 no valid proof that the species of the animals 

 examined, their health, or even the nature 

 of their food, ever effects any such quali- 

 tative alteration in this secretion. In respect 

 to the third, we may point out, that the vari- 

 able (and often large) quantity of lactic 

 acid is precisely what might be expected, 

 supposing it to be a secondary production. 

 And, according to Lehmann, the particular 

 variety of lactic acid seen in the stomach is 

 that produced by the fermentation of sugar, 

 and not that obtained from the fluid of muscle. 

 This fact has induced me to conjecture, that 

 the lactic acid thus observed can scarcely be 

 directly secreted from the blood. But it 

 must remain for future experiments to decide, 

 whether its absence in the later (and appa- 

 rently exact) analyses of Bidder and Schmidt, 

 was due to the exclusion of saliva, to the 

 fresh state in which the gastric juice was 

 examined, to its careful separation from all 

 food and peptone, or, finally, to the avoidance 

 of the process of distillation. Still, waiting 



* Lehmann (vol. i. p. 97.) urges against this ob- 

 server, that, in a previous analysis, he had failed to 

 find carbonate of soda in the ash of the blood : an 

 argument which seems somewhat invidious as well 

 as inconclusive. 



f Lehmann, Op. cit. vol. iii. p. 331. 



j Compare Lehmann, vol. ii. p. 42. ; vol. iii. p. 33, 



