AN ANIMAL PIGMENT CONTAINING COPPER. 
529 
definite organic pigment containing as an essential constituent about 7 per cent, of 
metallic copper. 
II. The “ turacin-bearers ” comprise all the known species of the three genera, 
Turacus, Gallirex, and Musophaga, while from all the species of the three remaining 
genera of the family Musophagidse, namely Corythceola, Schizorhis, and Gyrnno- 
schizorhis, turacin is absent. Furthermore, the zoological arrangement of the genera 
constituting this family is in accord with that founded on the presence of turacin. 
III. The spectrum of turacin in alkaline solution shows, besides the two dark 
absorption bands previously figured, a faint, broad band on either side of line F, and 
extending from X 496 to X 475. 
IY. The spectrum of isolated turacin in annnoniacal solution shows, besides the 
three bands already named, a narrow fourth band, lying on the less refrangible side 
of line D, and extending from X 605 to X 589. It probably arises from the presence 
of traces of the green alteration-product of turacin formed during the preparation of 
that pigment in the isolated condition, an alteration-product which is likely to prove 
identical with Krukenberg’s turacoverdin. 
Y. Turacin in ammoniacal solution remains unchanged after the lapse of 23 years. 
VI. Turacin in the dry state, when suddenly and strongly heated, yields a volatile, 
copper-containing red derivative, which, though undissolved by weak ammonia-water, 
is not only soluble in, but may be crystallised from ether. 
VII. Turacin in the dry state, when heated in a tube surrounded by the vapour of 
boiling mercury, becomes black, gives off no visible vapour, is rendered insoluble in 
alkaline liquids, and is so profoundly changed that it evolves no visible vapour when 
afterwards strongly heated. 
VIII. The percentage composition of turacin is probably carbon 53*69, hydrogen 4*6, 
copper 7*01, nitrogen 6*96, and oxygen 27*74 ; turacin may possibly be represented by 
the empirical formula, C 83 H 81 Cu 2 N 9 0 32 . 
IX. Turacin presents some analogies with hsematin, and yields by solution in oil 
of vitriol a coloured derivative having a spectrum much resembling that of lnemato- 
porphyrin, the corresponding derivative of hsematin, but retaining, unlike hsemato- 
porphyrin, part of the metallic constituent of the parent-substance. 
The rarity of turacin and the singular difficulty experienced in burning it com¬ 
pletely may, I hope, be regarded as furnishing a legitimate apology for offering to the 
Society a long discussion of analytical results, for the lack of absolute decisiveness in 
the evidence brought forward as to the centesimal composition of the pigment, for the 
limited information obtained as to the behaviour of turacin with reagents, and as to 
its relationships and derivatives. When one looks back upon the steps by which the 
true formula of so definite and abundant a crystalline pigment as alizarin was finally 
established ; when one recalls the mystery still shrouding haemoglobin and chlorophyll, 
some excuse may perhaps be allowed for my failure to accomplish more towards the 
elucidation of a colouring matter so anomalous and costly as turacin. It is, however, 
mdcccxcit.—a. 3 v* 
