BILIRUBIN. 429 



and which shows great similarity to the urinary pigment, urobilin, as well 

 as to stercobilin found in the contents of the intestine (MASIUS and 

 VANLAIR 1 ). The reduction products have been carefully investigated 

 by H. FISCHER and then by PAUL MEYER and F. MEYER-BETZ. They 

 have found that hydrobilirubin is a mixture of bodies, among which there 

 is one which forms at least one-half and therefore, called hemibilirubin, 

 gives colorless crystals, and according to FISCHER and MEYER-BETZ 

 is identical with the urobilinogen of the urine. The formula of this 

 body is, C32H44N4Oe or CssH^^Oe. The other body is amorphous 

 but in properties and composition shows great similarity to the hemi- 

 bilirubin. The analyses correspond closely to the formula, C32H4oN4Oe. 

 This body as well as the hemibilirubin yields hsematinic acid and methyl- 

 ethylmaleic imide on oxidation. As KUSTER 2 first showed, bilirubin 

 yields hsematinic acid as oxidation product. It does not on the con- 

 trary yield methylethyl maleic imide. 



PILOTY and TnANNHAUSER 3 obtained bilinic acid, CuH^e^Os 

 from bilirubin on reduction with hydriodic acid and iodophosphonium. 

 This acid corresponded to the h^matopyrrolidine carboxylic acid obtained 

 from ha3matoporphyrin. This bilinic acid is identical with the bilirubinic 

 acid described below and hence has this name. 4 They also obtained an 

 isomeric acid to phonopyrrolic acid, the isophonopyrrol carboxylic acid 

 and in the potash fusion they found partly a dimethyl- and partly a 

 trimethylpyrrol. From bilinic acid they later obtained on mild oxida- 

 tion an intensely yellow colored acid, the dehydrobilinic acid. 



From bilirubin and hemibilirubin, on heating with sodium methylate, 

 H. FISCHER and RosE 5 have obtained 2, 4, 5- trimethylpyrrol-3-propionic 

 acid which was previously obtained by H. FISCHER and BARTHOLOMAUS 

 from phonopyrrolcarboxylic acid. From bilirubinic acid on the con- 

 trary, with the same procedure they did not obtain this acid but another, 

 xanthobilirubinic add, CnH^^Oa, which is probably identical with 

 dehydrobilinic acid, and which contains two atoms of hydrogen less than 

 .bilirubinic acid, and which can be retransformed into the latter by glacial 

 acetic acid and hydriodic acid. As bilirubin, as well as hemibilirubin, 

 yields xanthobilirubinic acid as a side product with sodium methylate, 

 these experimenters consider this as a proof that the bilirubinic acid con- 



1 Maly, Wien. Sitzungsber., 57, and Annal. d. Chem., 163; Masius and Vanlair, 

 Centralbl. f. d. med. Wissensch., 1871, 369. 



2 Hans Fischer, Zeitschr. f. physiol. Chem., 73, with Paul Meyer, ibid., 75, with 

 Meyer-Betz, ibid., 75; Kiister, ibid., 26 and Ber. d. d. chem. Gesellsch, 32 and 35. 



3 Piloty and Thannhauser, Annal. d. chem. u. Pharm., 390 and Ber d. d. chem. 

 Gesellsch., 45. 



4 Piloty, Ber. d. d. chem. Gesellsch., 46, 1000; H. Fischer, ibid., 46, 1574. 

 6 Ber. d. d. chem. Gesellsch., 46, 439. 



