CHEMICAL BASIS OF THK ANIMAL i;DV. 245 



3. Bilicyanin. 1 (Cholecyanin, Choleverdin.) 



Tliis is tin- sul istance which results from the oxidation of bili- 

 verdin and is the cause of the blue colour ..li-ened \vh.n l.jl<- is 

 treated with fuming (yellow) nitric acid as in (Imdin's n-u. -lion. 

 It has not as yet been isolated either in sufficient quantity, and 

 still less in a condition of suflieieiit purity, tn admit of such a 

 chemical investigation as would lead to the determination . 

 composition. But by analogy with the known relationship of 

 liiliverdin to bilirubin, and from the evidence afforded by the 

 composition of choletelin (see below ) into which hilicyanin may 

 idily converted by further oxidation, hilicyanin will probably 

 be found to differ from biliverdin -imply by the addition of oxygen 

 to the molecule of the latter. 



Preparation. Bilirubin is dissolved in chloroform or suspended 

 in alcohol and slowly oxidised either by gradual addition ( ,f l.p.- 

 mine or fuming nitric acid; as soon as the mixture is of a bright 

 Line colour, the bilicyanin is precipitated by an BXCen ot' v 



As thus ohtained it is insoluble in water, almost in.-oluhle in either 

 ether or chloroform, but soluble in alcohol and alkalis. In 

 ence of alkalis it is still almost insoluble in either ether or chloro- 

 form ; in presence of acids it is now scarcely soluble in water, but 

 soluble in ether and chloroform. 



r.ilicyanin i- for practical purposes characterised solely by its 

 marked absorption spectrum. This consists of three Lands. one 

 on cadi side of J), that to the red side of D liein^ the darkest, and 

 one between /< and /'. The latter is probably identical with tin- 

 band seen in acid solutions of choletelin and due to the produc- 

 tion of this substance in small quantity during the oxidation of 

 bilirubin. The position of the hands varies somewhat according 

 to the solvent employed and as to whether the solution is acid or 

 alkaline. 



Durinu' the application ..f Cm.-lin's test f..r l.ile-pi^ ..... nts tin- Mm- 

 due t. liiliryuiiin is L.rdered l.y a \ i<det ci.l..ur and tin- l-y a n-|. tin- 

 final and pennaiient cd"iir l.einjj yellow. ( M" these three the first is 

 ii-.t as yet kn-.wn ti In- definitely due 1.. ..nc s|..'.-ilic siil. stance; it is 

 ni..st |. rnl.al.lv the result .f a n;i\tur of the blue of Lilicyauiii \\itli 

 tin- red .,f the next pr..Iurf. The r. d <-..!. ,ur i- ..n tl ..... tln-r hand 

 .siipp..seill\ due t<> a definite pi^uieiit s. mi. linn- called lilipur|iurin. 

 ..I' which li. \ve\er IK. tiling definite i- a> yet kimwn. 'I'll.' yell-.w 

 iiiarks the final t'nnat inn <>f cli.det.din. 



I CholeteHn. (V.H.-NW 



This is the final product ..f the oxidation of bile-pi^ment- 

 dily obtained l.y siis]M-ndinu r l-iliruhin in alcohol .:: 



1 Hoynsins n. C.iin|.l.o]1, I'H.i-. :>26. x. lt75, 3. 4. 



gives lilrraturv .f this ami ..tlicr l.ili- ]>i-4iiients. 



