518 
PROFESSOR A. H. CHURCH ON TURACIN, 
My former description of the effects of heat upon turacin needs one important 
addition. The violet, or rather purple vapour given off when dry turacin is strongly 
and suddenly heated, consists of, or contains, an organic compound of which copper is 
an essential constituent. This vapour condenses on cooling into a partly crystalline 
sublimate, which, unlike turacin, is soluble in ether and in alcohol, but insoluble in 
dilute ammonia. It is of a reddish colour, and is obtained in the crystalline state by 
the spontaneous evaporation, in dry air, of its etherial solution. It well deserves 
further investigation, for the complete analysis of this derivative could hardly fail to 
throw light upon the constitution of turacin itself. For the same reason, the derived 
pigment obtained by means of sulphuric acid merits extended study; for this latter 
body I propose the name of turacoporphyrin. 
If the very limited amount df turacin at my command has prevented me from 
making with it certain chemical and physical experiments which might have helped 
to elucidate its nature, and to determine its molecular weight, yet the study of its 
characteristic spectra has afforded invaluable aid in its recognition, especially in the 
case of the rarer species of Turacus. The chief features of these spectra were given in 
my former paper. The two well-marked absorption bands in the spectrum of turacin 
as it exists in the feather, closely resemble those of oxyhsemoglobin; the two chief 
bands in an alkaline turacin solution are not unlike those of CO-hsemoglobin. But it 
was desirable to investigate the spectroscopy of this unique pigment more thoroughly 
by examining solutions of different strengths, and prepared in different ways. 
For the series of drawings of turacin-spectra reproduced on p. 519, I am indebted 
to the skill and kindness of Dr. C. A. MacMtjnn, of Wolverhampton. This able 
experimenter, whose acquaintance with the spectroscopy of animal pigments is 
unrivalled, gives the following explanatory notes concerning the chart of spectra. 
The spectra were mapped by means of a one-prisnr chemical spectroscope made by 
Mr. Adam Hilger. The solutions were examined in a Preyer’s hsematinometer, 
which is provided with plane parallel glass sides one centimetre apart; the layer of 
solution examined was thus one centimetre thick. 
Fig. 1. Solar spectrum with some of the Fraunhofer lines, the scale at the top being 
the arbitrary one of the instrument. 
Fig. 2. Spectrum of the crimson web of a feather of Musophaga violcicea with 
transmitted light. The feather was mounted in front of the slit, the light of a 
so-called “ Sun ” Argand gas-burner being condensed upon it it by means of a bull’s- 
eye lens. All the remaining spectra figured were observed by means of the same 
light source. The following are the approximate measurements, in millionths of a 
millimetre, of the wave-lengths of the absorption-bands in the spectrum of this 
feather:—1st band, named a : shading begins at X 599, is dark at 597, extends dark 
to 571, shades off to 567*5 ; centre is at 585 or 583. 2nd band, named /3 : is feebly 
shaded at 557, becomes dark at 553*5, extends dark to 529, is shaded off to 521*5 ; 
oentre is at 538. The shading at the violet end begins about 510. 
