35 



CHEMISTRY OF THE DIGESTIVE PROCESSES. 



Konowaloff l collected over 10 litres, as above described, and sub- 

 jected the fluid to chemical examination. It was a clear, colourless, 

 odourless fluid, which could be kept indefinitely without undergoing 

 decomposition. When diluted with its own volume of water, it becomes 

 somewhat cloudy ; with four volumes of water, a permanent opalescence 

 resulted, which on further dilution eventually disappeared. On neutral- 

 ising with alkali, a flocky precipitate appeared, redissolving in the slightest 

 excess. Cooling the juice to 10-11 C. caused a finely granular precipit- 

 ate to appear, which dissolved again on warming. Its specific gravity 

 averaged 1*00478 ; total solids, 0*478 per cent. ; acidity, equivalent to 

 0*544 per cent, of hydrochloric acid. When the acid gastric juice is so 

 removed the reaction of the urine becomes alkaline 2 (0*96-1*31 per cent, 

 of Na 2 0). 



Freshly secreted gastric juice is aid to contain traces of proteid, 3 

 which, on standing, is converted into albumoses and peptones ; these, with 

 traces of mucin, and the two enzymes, pepsin and rennin, are the only 

 organic constituents. 



The inorganic salts consist chiefly of chlorides (with traces of phos- 

 phates) of sodium, potassium, and calcium, and traces of magnesium 

 and iron. 



The total amount of solids in gastric juice is very small, seldom 

 amounting to more than 2 per cent., and often being much less. Excess 

 of alcohol causes a flocky precipitate containing all the organic matter. 



Alkalies and alkaline carbonates added to gastric juice cause a 

 cloudiness or a flocky precipitate of tricalcic phosphate, with traces 

 of phosphates of iron and magnesium, and some organic matter. The 

 precipitation of tricalcic phosphate by ammonia shows that calcium is 

 present as acid phosphate in gastric juice. 



Quantitative Composition of Gastric Juice. 



The analyses are by C. Schmidt, quoted from Maly, Hermann's "Handbucli," Bd. v. (2) 

 S. 70 ; Ann. d. Chem., Leipzig, 1854, Bd. xcii. S. 42 ; and " Verdauungssafte," S. 44. 



Analysis I. is of human gastric juice, obtained from Schmidt's case of 

 gastric fistula already quoted it is evident that this gastric juice contained 



1 Inaug. Diss., St. Petersburg, 1893; Jahresb. it. d. Fortschr. d. Thier-Chem., Wies- 

 baden, 1893, Bd. xxiii. S. 289. 



2 Schoumow-Simanowsky, Arch, de sc. bioL, St. Petersbourg, 1893, vol. ii. p. 462. 



3 Hammarsten, "Lehrbuch der physiol. Chem.," Wiesbaden, 1895, Aufl. 3, S. 233. 



