THE CHEMISTRY OF THE ANIMAL BODY. 991 



quantities as a urinary sediment, still more rarely as a stone in the bladder 

 (see p. 986). It is laevo- rotatory. 



It is reported 1 that bodies having the composition C S H (thio- acids, mercaptans) 

 may form sulphuric acid, while most of those having the composition EEC S C:E 

 (ethyl sulphide) are not oxidized in the body. 



/9-Oxybutyric Acid, CH 3 CHOHCH 2 COOH. A lasvo-rotatory acid (see 

 p. 981). 



AMIDO- DERIVATIVES OF CARBONIC ACID. 



Carbonic acid. Carbamic acid. Carbamide. 



Carbamic Acid. This is not known free, but its calcium salts have been 

 found, especially in herbivorous urine, and its presence in the blood as ammo- 

 nium carbamate is maintained. 2 The latter has been obtained by Drechsel 3 by 

 oxidizing glycocoll and leucin in ammoniacal solution, and he has converted it 

 into urea by electrolysis. From these facts he concludes that ammonium car- 

 bamate is the antecedent of urea. 



Ammonium carbamate is formed by the direct union of ammonia with car- 

 bonic oxide in their nascent states, and is therefore found in commercial ammo- 

 nium carbonate and as the product of the oxidation of the amido- compounds 

 above mentioned : 



Water converts it into ammonium carbonate : 



Carbamide, or Urea, OC(NH 2 ) 2 . This is the principal end-product of the 

 nitrogenous portion of proteid in all mammals, being found in considerable 

 concentration in the urine. It may be detected in the blood in traces, in 

 lymph, and in the liver, but Liebig could find no trace of it in muscle. In 

 uraemia it may collect in all tissues of the body, and may then be excreted 

 in slight amount by the gastric and intestinal juices. It is given off in profuse 

 sweating, though only in small proportion to that lost in the urine. 



Preparation. (1) Like other amides, by heating ammonium carbonate ; 

 further, by the electrolysis of, or by heating, ammonium carbamate : 



~\TTT 



1 W. J. Smith : Pfluger's Archiv, 1894, Bd. 55, p. 542, and 1894, Bd. 57, p. 418. 



2 Drechsel: Ludwiy's Arbeiten, 1875, p. 172; Drechsei und Abel, Archiv fur Physiologic, 1891, 

 p. 242. 



Loc cit. 



