HAP. IV.] BILIVERDIN. HYDROBILIRUBIN. 325 



analyses of biliverdin made by Maly and by Thudichum himself. A 

 comparison of the two sets of ^analytical results and of the empirical 

 formulae for bilirubin and biliverdin deducible from them establishes 

 that biliverdin differs from bilirubin only in containing more oxygen. 

 A study of the relations of bilirubin to biliverdin, and of 

 tribromobilirubin have led chemists to double the formula originally 

 -assigned to bilirubin by Stadeler as well as that originally assigned 

 to biliverdin by Maly. The relation of bilirubin to biliverdin is 

 expressed in the equation 



Ci.H^O. + O.-Q.H.NA. (Maly.) 



Bilirubin. Biliverdin. 



SECT. 9. SOME DERIVATIVES OF THE NORMAL BILIARY COLOURING 



MATTERS. 



1 . Hydrobilirubin, 



If the normal bile colouring matters are amenable to the action 

 of reducing agents, their reduction must, without a doubt, be 

 effected in the intestinal canal, where the presence of free hydrogen, 

 the development of sulphuretted hydrogen, &c. shew that conditions 

 exist which are adequate to the reduction of organic bodies. Such 

 was the reasoning which led Richard Maly 1 to commence the investi- 

 gation of the products of reduction of bilirubin. 



Preparation. Bilirubin prepared from the gall-stones of the ox 



was suspended in water to which was added sodium 

 amalgam in small pieces. At the commencement of the process no 

 gaseous hydrogen was evolved. The suspended bilirubin was soon 

 dissolved by the sodium hydrate resulting from the reaction ; after 

 some time the brown solution became gradually lighter in colour 

 and, on being shaken, bubbles of hydrogen gas were evolved. An 

 excess of sodium amalgam being added, the process was allowed to 

 go on at ordinary temperatures for two or three days and then, by 

 the aid of gentle heat, on the water bath, until no further change 

 in the colour of the solution could be observed. The solution, being 

 decanted from the subjacent mercury, was treated with an excess of 

 hydrochloric, or acetic, acid. The addition of acid proved, at once, 

 that the bilirubin had been acted upon, for the liquid assumed a 

 dark garnet-red colour. The greater part of the colouring matter is 

 under these circumstances precipitated in dark red-brown flakes, 

 though a part remains dissolved. In proportion as the precipitate is 

 freed from alkaline chloride by washing, it becomes less soluble, so 

 that when it contains neither chlorine nor fixed residue the washings 

 merely exhibit a pale rose-red tint. 



1 Maly, ' Untersuchungen \iber die Gallenfarbstoffe. in. Umwandlung von Bilirubin 

 in Harnfarbstoff,' Annal. d. Chem. u. Pharm., Vol. CLXIII. pp. 77 95. 



