CHEMICAL BASIS OF THE ANIMAL BODY. 261 



several coloured products and of their not having undergone some 

 change during the operations involved in their preparation, no 

 authoritative statement on this point can as yet be made. Indeed 

 the whole subject of the origin, nature and relationships of urinary 

 pigments is at present in a state of considerable confusion and 

 uncertainty 1 . 



The urinary pigments so far dealt with may be regarded as either 

 normal or pathological, or as resulting from the spontaneous or 

 artificial decomposition of urinary constituents which are at the outset 

 colourless. In addition to these, other colouring substances are not 

 infrequently observed, or colour-reactions obtained, in urines passed 

 after the administration of certain drugs or the consumption of certain 

 vegetable tissues. They are in many cases not unimportant as leading 

 at first sight to possibly erroneous conclusions as to the presence 

 in urine of pathologically important pigments, e.g. of bile or blood. 

 After the administration of rhubarb or senna the urine may be 

 yellow or greenish-yellow, due to the presence of chrysophanic acid 

 [C 14 H 5 (CH 3 )(OH) 2 2 ], and similarly after the use of santonin (C 15 H 18 O 3 ). 

 In such cases if the urine is strongly alkaline it may be of a red 

 colour ; this is changed to yellow on the addition of hydrochloric acid, 

 and if it is initially acid, it turns red on the addition of an excess of 

 alkali 2 . After the internal administration of copaiba, the urine turns 

 pink or rose-coloured on the addition of hydrochloric acid and shows 

 three absorption bands, one (narrow) in the orange to the red side 

 of 7), one broad band in the green between D and E, similar to that 

 of fuchsin, and one in the blue 3 . Tannin leads to the appearance 

 in urine of gallic acid fC 6 H 2 . (OH) 3 . COOH], which is hence sometimes 

 found normally in the urine of herbivora (horse) 4 . In such cases the 

 urine if made alkaline with caustic potash turns brown, and bluish- 

 black on the addition of ferric chloride. It also yields a pink 

 colouration with Millon's reagent, similar to that given by proteids 

 or tyrosin. After doses of antipyrin [C 9 H 6 N 2 O(CH 3 ) 2 ] the urine may 

 be dark-coloured and gives a brownish-red colour on the addition of ferric 

 chloride 5 . Fuchsin (hydrochloride of rosaniline C^E^l^ . HC1) reappears 

 partly unchanged in the urine, to which it imparts a reddish tinge. 

 It is detected by making the urine alkaline with ammonia and shaking 

 with an equal volume of ether : the latter extracts the colouring 



1 For further literature of these red pigments see Mester, loc. cit. S. 143. Also 

 Berl. Bin. Wochensch. 1889, Sn. 5, 202, 490, 520, 953 ; 1890, S. 585. Centralb. f. 

 kiln. Med. 1889, S. 505. Stokvis (Dutch), Abst. in Maly's Bericht. 1889, S. 462. 



2 For discrimination of these see Munk, Virchow's Arch. Bd. LXXII. 1878), 

 S. 136. 



3 Quincke, Arch. f. exp. Path. u. Pharm. Bd. xvn. (1883), S. 273. 



4 Baumann, Zt. f. physiol. Chem. Bd. vi. (1882), S. 193. 



5 Umbach, Arch. f. exp. Path. u. Pharm. Bd. xxi. (1886), S. 161. 



