244 BILIYERDIN. 



detection of minute amounts of bile-pigments in urine is frequently of great 

 clinical and physiological importance. If any very appreciable quantity of the 

 pigments are present, Gmelin's reaction applied as above will usually suffice to 

 detect them. If not they may be obtained in a more concentrated residue, which has 

 been largely freed by Huppert's method from other colouring matters which interfere 

 with the test. The fluid is precipitated by lime-water and carbon dioxide. 

 The compound of lime and bilirubin is then collected on a filter, washed and 

 tested in situ by the addition of fuming nitric acid ; or it may be boiled in a 

 test-tube with a little alcohol acidulated with sulphuric acid ; the precipitate 

 loses its colour and the supernatant alcohol turns to a brilliant green. The 

 following is also a reliable test as applied to urine 1 . To 20 or 30 c.c. of urine 

 add 5 to 10 c.c. of a solution of zinc acetate (1 : 5). This causes a voluminous 

 precipitate of bile-pigments, especially if the acid reaction be somewhat reduced 

 by the simultaneous addition of a little sodium carbonate. The precipitate is 

 collected on a filter, washed with water and dissolved in a little ammonia. If 

 bile-pigments are present the solution is usually fluorescent and on standing, 

 if not at once, shows the absorption bands characteristic of bilicyanin. (See 

 below.) For further details of other methods consult some special work 2 . 



The accurate quantitative determination of bilirubin, as of other 

 bile, and also of urinary-pigments is only possible by spectrophotometric 

 methods. These have been already briefly described on p. 226. The 

 requisite constants for the application of the method in the case of 

 each pigment are given in the literature quoted below 3 . 



Bilirubin while it exhibits no distinct absorption-bands, is charac- 

 terised by a powerful absorption of the violet end of the spectrum. 



2. Biliverdin. C 16 H 18 N 2 4 - 



This is, as already stated, the first product of the oxidation of 

 bilirubin. It gives the characteristic colour to the bile of herbivora, 

 probably accounts for the colour of biliary vomit in carnivora (man), 

 is possibly found in the urine in icterus, has been stated to occur in 

 the edges of the placenta in pregnant animals 4 (bitches), while on the 

 other hand it occurs in mere traces in gall-stones whether of man or 

 other animals. It has also been described as occurring in egg-shells 5 

 and the integuments of certain invertebrates 6 . 



/. klin. Med. 1884, No. 45, or Centralb.f. d. med. Wiss. 1884, S. 143. In the latter 

 case a solution of diazobenzosulphonic acid is employed and is stated to discriminate 

 between bilirubin and other bile pigments. 



1 Stokvis. See Abst. in Maly's Jahresb. 1882, S. 226. 



2 Neubauer u. Vogel, Anal. d. Earns, 1890, S. 321 et seq. 



3 Vierordt, Die quant. Spectralanalyse u. s. w. Tubingen, 1876, S. 76. Zt. f. 

 Biol. Bd. ix. (1873), S. 160, Bd. x. (1874), S. 21, 399. Vossius, Arch. f. exp. 

 Pathol. Bd. xi. (1879), S. 427. 



4 Etti. See Maly's Jahresb. 1871, S. 233, and 1872, S. 287. 



5 Liebermann, Ber. d. d. chem. Gesell. Bd. xi. (1878), S. 601. Krukenberg, 

 Verhandl. d. physik.-med. Gesell. zu Wiirzburg, Bd. xvn. (1883), S. 109. 



6 Krukenberg, Centralb.f. d. med. Wiss. 1883, S. 785. 



