324 BILIVERDIN. [BOOK n, 



action of peroxide of lead, the change taking place with extra- 

 ordinary rapidity. To an alkaline solution of bilirubin some Pb0 2 

 is added and the mixture is stirred. In a couple of minutes the 

 fluid assumes a dark green colour. On now faintly acidifying it with 

 acetic acid, a compound of biliverdin with lead falls. This is decom- 

 posed by means of alcohol containing sulphuric acid in solution. The 

 alcoholic solution, filtered from precipitated lead sulphate, is poured 

 into water and the flocculent precipitate of biliverdin is collected. 



Physical and 'Biliverdin is a blackish green solid which is usually 



chemical pro- amorphous, but which has occasionally been obtained 



* m ~ tne form of green rnoml:)ic P lates with truncated 

 ends, by evaporating its solution in glacial acetic acid. 

 It is insoluble in water, ether, pure chloroform, benzol, and carbon 

 disulphide. It is readily soluble in ethyl alcohol, methyl alcohol, in 

 glacial acetic acid and also in chloroform which contains alcohol, or 

 which has been mixed with glacial acetic acid. It dissolves in 

 concentrated sulphuric acid, forming a solution which is precipitated 

 by water. Strong hydrochloric acid dissolves some biliverdin. Acid 

 solutions of biliverdin e.g. solutions in glacial acetic acid, are of a 

 beautiful fiery-green colour. Neutral solutions are of a sap-green 

 colour, whilst solutions in alkalies are yellowish-green or brownish- 

 green and are precipitated by acids. Solution of calcium and barium 

 hydrates throw down, from alcoholic solutions of biliverdin, flocculent 

 Ba- and Ca-compounds. Solutions of biliverdin exhibit with the 

 spectroscope no definite absorption bands. The absorption increases 

 from the red towards the violet end of the spectrum, so that the 

 extreme red is 16 times less absorbed than the violet between G 

 and HV 



Composition Heintz had discovered that when the reddish- 



of biliverdin yellow colouring matter of the bile is introduced into 



and its reia- absorption tubes, containing oxygen and standing over 



mercury, as the colouring matter assumes a green tint 



the volume of oxygen diminishes. Stadeler, as a 



result of his analyses, believed that biliverdin differed from bilirubin, 



as shewn by the following equation : 



Ci 6 H 18 N 2 3 + H 2 + = C 16 H 20 N 2 5 (Stadeler). 



Bilirubin. Biliverdin. 



The concordant analyses of Maly and of Thudichum both agree 

 in assigning to biliverdin a formula differing from that of Stadeler 

 (C 8 H 9 NO 2 )w. Thudichum, whose formula of bilirubin (C 9 H 9 N0 2 ) is 

 obviously incorrect, has expressed the view that when that body is 

 converted into biliverdin it is due to an oxidation which leads to an 

 elimination of C0 2 . This view is unquestionably founded on error, 

 and is disproved, firstly by the concordant analyses of pure bilirubin 

 made by Stadeler, Maly and Hoppe-Seyler, and secondly by the 



1 Maly, Hermann's Handbuch, Vol. vn. p. 159. 



