188 
Proceedings of Royal Society of Edinburgh . [sess. 
A Contribution to the Chromatology of the Bile. By 
John Berry Haycraft, M.D., D.Sc., and Harold Scofield, 
M.B. 
(Read March 4, 1889.) 
One of the chief biliary pigments is bilirubin. It has a red-orange 
colour, and is derived from the decomposition of hsemoglobin. It 
can be oxidised first into a green, then into a blue, then into a red, 
and finally into a yellow-brown pigment. Between the blue and 
red a violet substance is produced, but it is uncertain whether or 
not this is only a mixture of the blue and red pigment. The forma- 
tion of the green pigment, according to Stadeler,* is due to oxidation, 
together with the addition of a molecule of water. These pigments 
do not always present exactly the same characters. Thus, according 
to Dr MacMunn, the green pigment present in the ox-bile differs 
from what is artificially produced from the oxidation of bilirubin, 
say, from human bile, in that it is soluble in chloroform. f This 
pigment can, however, he oxidised up into the blue pigment, and so 
on ; and it belongs, therefore, to what we may term the bilirubin 
series. Its colour indicates its position in the scale of oxidised 
products. We shall in this paper use the term biliverdin as desig- 
nating a green pigment, which is more oxidised than the bilirubin, 
and bilicyanin as designating a blue pigment still more oxidised. 
The violet substance (if such exist) we shall term the violet pig- 
ment, the red oxidation product the red pigment, and, finally, the 
yellow T -brown pigment, the most highly oxidised product of all, 
choletelin. 
Although, by the action of an oxidising agent, such as impure 
nitric acid, it is easy to pass from a lower to a higher member of 
the bilirubin series, it is frequently, and we believe truly stated, 
that no successful attempt has been made to reduce the higher back 
again to the lower ones. By the reducing action of, say, sodium 
amalgam, hydrobilirubin (C 32 H 40 M 4 O 7 ) has been produced both from 
bilirubin and from biliverdin. When, however, ox-bile is placed in 
a tall vessel, and allowed to remain for some hours, we have observed 
that a change in colour takes place. If blue pigment is present 
* Gorup-Besanez, Physiol . Chemie , p. 207. 
t Jour, of Phys., vol. vi. p. 2. 
