506 AN AMERICAN TEXT-BOOK OF PHYSIOLOGY. 



feces, as sulphuretted hydrogen in the intestinal gas, as sulphate and other 

 unknown compounds in the urine. 



Sulphuretted Hydrogen, II..S. — This gas is found in the intestines, and 

 pathologically in the urine. 



Preparation. — (1) Action of hydrochloric or sulphuric acid on ferrous 



sulphide, 



FeS + H 2 SG 4 = FeS0 4 + H 2 S. 



This same reaction takes place by treating feces (which contain FeS) with acid. 



(2) From the putrefaction of proteids, and by boiling proteid with mineral 

 acid. 



Properties. — Sulphuretted hydrogen unites readily with the alkalies and 

 with iron salts, forming sulphide; hence little H 2 S is found in the intestinal 

 tract. It is a strong poison when respired. It has been shown to enter into 

 combination with oxyhemoglobin to form sulph-hsemoglobin, and likewise 

 in frogs it rapidly kills the nerves. 1 Sulphuretted hydrogen diluted with 

 hydrogen and introduced into the rectum of a dog produces symptoms of 

 poisoning in one to two minutes (Planer). It has an offensive odor similar 

 to foul eggs. 



Sulphurous Acid, H 2 SO :! . — This acid has been found in the urine of cats and dogs, 

 and lias been detected by Striimpell in human urine in a case of typhoid fever. 



Sulphuric Acid, H 2 S0 4 . — This acid is found in the urine in combination 

 with alkali (preformed sulphate), and with indol, skatol, cresol, and phenol 

 (ethereal sulphates). It is found in the saliva of various gastropods. 



Preparation. — (1) By oxidation of sulphur with nitric acid, 



S + 2HND 3 = H 2 S0 4 + 2NO. 



(2) By oxidation of sulphur-containing proteid, 



Properties. — Sulphuric acid is a very powerful acid. It is produced in the 

 body by the burning of the proteids (which contain 0.5 to 1.5 per cent. S), 

 80 per cent, or more being oxidized to acid, while the remainder appears in the 

 urine in the unoxidized condition termed neutral sulphur. When proteid, fat, 

 and starch free from ash are fed to dogs, they live only half as long as they 

 would were they starving, 2 for, according to Bunge, 3 the sulphuric acid formed 

 abstracts necessary salts from the tissue. (For further discussion of this see 

 pp. 354 and 525). 



Tf 100 cubic centimeters of urine be treated with 5 cubic centimeters of hydrochloric 

 a<-id and barium chloride be added, the 'preformed sulphuric acid is precipitated as barium 

 sulphate (BaSOJ, which may be washed, dried, and weighed. It' 100 cubic centimeters 

 of urine be mixed with an equal volume <>t' a Bolution containing barium chloride and 

 hydrate, filtered, and one-half the fill rate ( = 50 cubic centimeters of urine, now free of 

 preformed Bulphate) be strongly acidified with hydrochloric acid and boiled, the ethereal 

 sulphates will be broken up, and the resulting precipitate of barium sulphate will corre- 

 spond to the ethereal sulphuric acid. To determine the neutral sulphur, evaporate the 



1 Harnack : Archiv fur expervmenteUe Paihdogie, wnd Pharmakofogie, 1894, Bd. 34, S. 156. 

 2 .1. Foster: Zeitschrifijur Biologie, 1873, Bd. 9, S. 297. 

 3 Physiologische Chemie, 2d ed., 1889, p. 104. 



