304 TURACIN. [BOOK i. 



Percentage The analyses which have been made of the various 



composition pigmentary matters included under the term Melanin 

 of Melanin. have led to widely discordant results. The carbon in 

 100 parts has varied between 51*7 and 58'3; the H between 4'02 and 

 5'09; the N between 71 and 13'8; the between 22'03 and 35'44 l . 



Pigments of the Feathers of Birds. 



The brilliant colours of the plumage of birds is due in part to 

 the optical characters of the surface of the feathers (interference- 

 colours) : in part to the presence, within the feathers, of colouring 

 matters, which may usually be extracted from them by alcohol, ether, 

 or hot acetic acid, and which, as a rule, are very unstable, becoming 

 decolourized by exposure to air. 



These colouring matters have hitherto not been subjected to a 

 thorough chemical investigation, with the exception of the one to be 

 described in the ensuing paragraph. 



Turacin. 



In various species of birds belonging to the family Musophagidae 

 and which, from the nature of their food, are designated Plaintain- 

 eaters, the primary and secondary pinion-feathers, are more or less of 

 a crimson colour. The colour is due to a pigment which has been 

 separated and analysed by Professor Church, who has applied to 

 it the name Turacin, from Tour aeon, the name by which the Plaintain- 

 eater is designated by the natives on the shores of the Gambia. 



The barbs constituting the red part of the web are 

 parating Tu- stripped from the shaft of the feathers, placed in a 

 racin. beaker, and washed with ether, then with alcohol. 



They are then dried, by pressure between folds of 

 filtering paper, and placed in a very dilute cold solution of pure 

 caustic soda, a solution containing one part of soda in a thousand 

 of distilled water being quite strong enough. The crimson pigment 

 is soon dissolved ; its solution is then poured into dilute hydrochloric 

 acid (1 of acid to 4 of water), when the red colouring matter is 

 precipitated. It is then washed, first with water, until all acid 

 reaction is removed, and then in alcohol and ether, and dried. 



Properties Occurs in scales which have a deep violet-purple 



of Turacin. colour by reflected light, and a crimson tint when seen 

 in small fragments by transmitted light. 



It has not yet been obtained in a crystalline form. It is very 

 slightly soluble in pure water, giving a pale rose-pink solution. It is 

 not soluble in alcohol or ether. It is insoluble in acid, but soluble in 

 alkaline liquids* 



Spectrum Turacin and the feathers containing it possess a 



of Turacin. spectrum which is almost identical with that of oxy- 



1 See a paper by Hodgkinson and Sorby entitled " Pigmentum Nigrum, the black 

 colouring matter contained in hair and feathers." Jcurn. Chem. Soc. 1877, p. 427. 



