CHEMICAL BASIS OF THE ANIMAL BODY. 915 



Hydrobilirubin. C 32 H 40 N 4 7 . 



This body was first described by Maly 1 as resulting from the action of sodium 

 amalgam on an alkaline solution of bilirubin. When the reaction is complete the 

 solution is precipitated with hydrochloric acid, the precipitate dissolved in ammo- 

 nia, again precipitated by acid, and the substance thus finally obtained is washed 

 with water. It is readily soluble in alcohol, less so in ether. Its alkaline solutions 

 are yellow, and these turn pink on the addition of acid. Both its acid and alka- 

 line solutions, the latter especially on the addition of a few drops of chloride of 

 zinc, give a characteristic absorption band between b and F. 2 In the colors of its 

 alkaline and acid solutions and the greenish fluorescence of its ammoniacal solution 

 on the addition of chloride of zinc, and in its absorption spectrum, hydrobilirubin 

 shows its close relation to the urobilin (see below), with which indeed it is now con- 

 sidered to be identical. It is also identical with a body named stercobilin, 3 which 

 had previously been described as a product of the alteration of the bile-pigments in 

 the alimentary canal occurring in feces. There is no difficulty in seeing how this 

 change (hydrogenation) can be brought about in the intestine since it is known that 

 a considerable quantity of hydrogen may make its appearance by fermentative pro- 

 cesses in the intestine, and in its nascent state might readily produce the simple 

 change which is known to occur when bilirubin is converted into hydrobilirubin. 



PIGMENTS OF URINE. 



Our knowledge of these bodies is at present limited and imperfect. Most prob- 

 ably 4 they are numerous, but only two appear sufficiently well characterized to 

 deserve mention here. 



Urobilin. C 32 H 40 N 4 7 . 



As stated above, this is now regarded as identical with hydrobilirubin. It was 

 first described by Jaffe 5 as a well-characterized normal urinary pigment and its 

 identity with hydrobilirubin subsequently determined. 6 



Normal urine contains only small quantities of urobilin, but there is present a 

 substance (chromogen) which under the influence of acids, with absorption of 

 oxygen, yields urobilin. The urine of fever frequently contains a considerable 

 amount of actual urobilin as such. 



The properties described above for hydrobilirubin are identical with those of 

 urobilin. Its preparation from urine is somewhat difficult, and for this some spe- 

 cial manual must be consulted. 7 



Uroerythrin. 



Is considered to be the substance which gives to the urine of rheumatism its 

 characteristic color. Very little is known of its chemical properties. 8 It appears 

 to be an amorphous reddish body with an acid reaction, slowly soluble in water, 

 alcohol, and ether. When treated with caustic alkali it turns green. Urine con- 

 taining this body takes on a characteristic reddish-yellow color on the addition of 

 concentrated hydrochloric acid. 



Thudichum considers that normal urine contains only one pigment, which he calls uro- 

 chrorne. 9 Maly is inclined to regard this as the same as urobilin. 10 More recently Thudichum 

 has upheld his former views. 11 



THE INDIGO SERIES. 

 Indican. C 8 H 7 NS0 4 . 



A body was long ago described 12 as occurring in the urine and sweat of men 

 and other animals which yielded by the action of acids the blue coloring matter 



i Centralb. f. d. med. Wiss., No. 54, 1871. Annal. d. Chem., Bd. clxiii. (1872), S. 77. 

 Vierordt, Zeitschr. f. Biol., Bd. ix. (1873), S. 160. 

 Vanlair and Masius, Centralbl. f. d. med. Wiss., No. 24, 1871. 

 Vierordt, Die quantitativ Spectralanalyse, etc., Tubingen, 1876, S. 81. 

 Centralb. f. d. med. Wiss., 1868, S. 243. "Virchow's Arch., Bd. xlvii. (1869), S. 405. 

 Maly, Ann. d. Chem. u. Pharm., Bd. clxiii. (1872), S. 77. 

 Vide Neubauer and Vogel, Harnanalyse, ed. viii. (1881), S. 81. 

 Heller's Archiv (2) Bd. iii. (1854), S. 361. 

 Brit. Med Journ., N. S., No. 201, 1864, p. 509. 



10 Maly, Ann. d. Chem. u. Pharm., loc. cit., 1872, S. 90. 



11 Journ. Chem. Soc., Ser. 2, vol. xiii (1875), pp. 397, 401. 



12 Schunk, Phil. Mag., vol. x. p. 73 ; xiv. p. 228; xv. pp. 29, 117, 183. Chem. Centralbl., 1856, S. 

 50 ; 1857, S. 957 ; 1858, S. 225. Hoppe-Seyler, Arch. f. path. Anat., Bd. xxvii., S. 388. Jaffe, Pfltiger's 

 Arch., Bd. iii. (1870), S. 448. 



