CHAP. IV.] BILICYANIN. CHOLETELIN. 329 



separate the blue colouring matter and described its spectroscopic 

 characters. * Stokvis named it,, in the first instance, choleverdin and 

 afterwards cholecyanin, whilst Heynsius and Campbell 1 applied to it 

 the term bilicyanin by which it is now known. 



Physical and The product which we are now considering has, 

 chemical pro- doubtless, not been obtained in a pure condition and 



bmc f ^ as never ^ een subjected to analysis. It is not there- 



fore surprising that the description of its properties, 

 given by the various persons who have investigated it, should differ 

 materially. As has already been stated, according to Stadeler, bili- 

 cyanin presents the appearance of a blackish-blue powder. Accord- 

 ing to Jaffe', if freed from every trace of acid it is not blue but dark 

 violet. It is insoluble in water but readily soluble in alcohol, ether 

 and choroform, imparting to these liquids a beautiful violet colour 

 which is changed into a lovely blue on the addition of a trace of 

 acid. 



Acid solutions of bilicyanin present two absorption bands which 

 are identical with those which are seen during the first stage of 

 Gmelin's reaction and which are situated on either side of the 

 D line (see Plate I., Spect. 3). The band between b and F which 

 can be seen in the spectrum of Gmelin's reaction is not due to 

 bilicyanin, as was supposed by Heynsius and Campbell, but to 

 the more oxidised product, choletelin. According to Jaffe, neutral 

 and alkaline solutions of bilicyanin exhibit no absorption bands. 

 According to Heynsius and Campbell, they present equally strong 

 absorption bands, though their position is different ; they are some- 

 what shifted towards the red end in the case of the neutral and 

 alkaline, as compared with the acid, solutions. 



Nature and Bilicyanin appears, unquestionably, to be a product, 



MiLc ti0n in' f or a m ^ xture f products, resulting from the moderate 

 oxidation of bilirubin and biliverdin. This oxidation, 

 if carried further, furnishes the body to be subsequently described as ' 

 choletelin. Bilicyanin occurs occasionally, in small quantities, in gall- 

 stones. 



Choletelin* (CJi^S^ ?) 



The name choletelin was given by Maly 3 to the product, or 

 mixture of products, which results from the prolonged action of nitric 

 and nitrous acids on the bile colouring matters, the formation of 

 which coincides with the final (yellow) stage of Gmelin's reaction, 

 which is, therefore, now often designated the choletelin stage. 



1 The reader who is specially interested in bilicyanin is referred* to the table of 

 spectra which accompanies the previously cited paper of Heyusius and Campbell. 



2 Derived from xM bile and rAos, the end. 



3 Maly, Sitzungsber. d. Wiener Akad. Vol. LVII. 2 Abth. Febr. 1868: Vol. LIX. 

 2 Abth. April, 1869. The account here given of choletelin is taken from the account 

 given by Maly, Hermann's Handbuch, Vol. vu. p. 165. 



