on the Presence of free Acids in the Stomach. 5 



great. It is probably owing to this cause that Prout found 

 no sal ammoniac in the liquid from the human stomach in two 

 cases ; although the complete absence of this salt from such 

 liquids is very unlikely*. From these observations it seems 

 probable that the proof of the presence of free muriatic acid, — 

 which Prout has lately endeavoured to deduce from the cir- 

 cumstance, that when the liquid of the stomach after having 

 been neutralized with potash was evaporated to dryness, and 

 the residue exposed to a red heat, this residue did not act 

 as an alkali but constituted a neutral salt, — is not satisfactory. 

 For a liquid of the stomach which contains no free muriatic 

 acid, but muriate of soda, muriate of ammonia, and free acetic 

 acid, must (if the quantity of acetic acid be not too great) after 

 neutralization with potash and ignition contain only chloride 

 of potassium and chloride of sodium. 



We are of opinion that Dr. Prout himself in his last state- 

 ment has admitted that when an organic acid is present, his 

 process is insufficient, and has thus confirmed our own pre- 

 vious statements. 



3. We have misrepresented Prout & opinion respecting the ap- 

 pearance of albumen in the intestines, by making him maintain 

 that no albumen exists in the liquid of the stomach even when 

 the animal takes food containing albumen; but that it shows it- 

 self first in the duodenum, in consequence of the union of the li- 

 quid of the stomach with the bile and the pancreatic juice. 



After again perusing Prout's former paper f , we must ac- 

 knowledge that we have stated his opinion on this subject quite 

 inaccurately. Whether this proceeded from misunderstanding 

 his meaning, or from an inaccurate extract from his paper, we 

 cannot say. We request the reader of our work to obliterate 

 the passage which refers to this misunderstanding on our part. 



We trust that these explanations and acknowledgements 

 will obviate the complaints of this celebrated chemist and phy- 

 sician, to whom the chemical part of physiology and pathology 

 lies under so many obligations. We have only to express 

 our high satisfaction at his statement, that his observations on 

 digestion agree with ours, and confirm them in the most im- 

 portant points. 



* It is true, Prout determined the quantity of sal ammoniac by another 

 method. From the total quantity of muriatic acid contained in the liquid, 

 he subtracted the portion united to a fixed alkali, and that which existed 

 in a free state. The remainder must represent the portion combined with 

 ammonia. But as the presence of acetic acid would lead him to overrate 

 the quantity of free muriatic acid, the sal ammoniac as thus estimated would 

 be too little or none at all. 



t Annals of Philosophy (first series), vol. xiii. p. 12. 



III. On 



