508 AN AMERICAN TEXT-BOOK OF PHYSIOLOGY. 



(2) By the art ion of strong sulphuric acid on common salt. 



L'XaCl + H 2 S0 4 = Na 2 S0 4 + 2HC1. 



(3) By the action of primary acid phosphate of sodium on common salt, 



NaCl NaH 2 P0 4 = Na 2 HP0 4 + HCl. 



This, according to Maly, represents the process in the cells of the gastric glands. 

 Properties. — Hydrochloric acid readily unites with most metals, forming 

 chlorides. It causes a gelatinization of the proteids and seems to unite with 

 them chemically. Such gelatinization is a necessary forerunner of peptic di- 

 gestion. The cleavage products of peptic digestion (peptones, proteoses, etc.) 

 combine with more hydrochloric acid than the original more complex proteid. 1 

 Free hydrochloric acid of the strength of the gastric juice (0.2 per cent.) 

 inverts cane-sugar at the temperature of the body, 2 and inhibits the action of 

 bacteria. Hydrochloric acid is derived from decomposition of chlorides in 

 the secreting cells of the stomach. It has been shown that the excretion of 

 common salt in the urine is decreased during those hours that the stomach is 

 active, while the acidity of the urine decreases. If, in a dog with a gastric 

 fistula, the mucous membrane of the stomach be stimulated and the gastric 

 juice be removed as soon as formed, the urine becomes strongly alkaline with 

 sodium carbonate (the excess of Na liberated taking this form) while the chlo- 

 rides may entirely disappear from the urine. 3 Respiration in an atmosphere 

 containing 0.5 per cent. HC1 gas becomes very uncomfortable after twelve 

 minutes/ 



It' the bases (K, Na. Ca. M>. r , Fe) of gastric juice and then the acid radicals (CI and 

 P 2 5 ) be determined, and the phosphoric anhydride be united with the proper bases, and 



then chlorine with the rest of the bases, there still remains an excess of chlorine which can 

 only have belonged to the hydrochloric acid present. To detect free hydrochloric acid put 

 three or four drops of a saturated alcoholic solution of tropseolin 00 in a small white porcelain 

 cover, add to this an equal quantity of gastric juice, evaporate slowly, and the presence 

 of hydrochloric acid is shown by a beautiful violet color, not given by any organic acid. 5 

 Griinzburg's reagent consisting of phloroglucin and vanillin in alcoholic solution, warmed 

 (as above) with gastric juice containing tree hydrochloric acid, gives a carmine-red 

 mirror on the porcelain, not given by an organic acid. 6 



CHLORINE in THE body is ingested as chloride, and leaves the body as 

 such, principally in the urine, likewise through the sweat and tears, and in 

 traces in the feces. 



Bromine, Br = 80. 



Salts of bromine are found in marine plants and animals, but their physiological im- 

 portance has not been established. Bromine is a fluid of intensely disagreeable odor, 



1 Chittenden: Qartwrighl Lectures on Digestive Proteolysis, 1895, p. 52. 



* Ferris and Lusk : American Journal of Physiology, 1898, vol. i. p. 277. 



3 E O. Schoumow-Simanowski : Arckiv fur a/per. Pathologie und Pharmakologie, 1894, Bd. 

 33, S. 336. 



* Lehmann : Archiv fur Hygiene, Bd. 5, S. 1. 



' Boas: Deutsche medicinische Wocketnschrift, 1887, No. 39. 

 '• < iiinzburg : Centralblatt fiir Iclinische Medicin, 1887, No. 40. 



