CORAL PIGMENTS. 185 
On evaporating the alcohol solution to dryness on the water-bath, a residue partly 
brown and partly green was obtained, soluble in absolute alcohol, forming a dull green 
solution with a red fluorescence. In this solution the four bands referred to above were 
visible, but no lipochrome bands. The residue is also soluble in ether, in chloroform and 
in carbon disulphide, each solution showing the same chlorophylloid spectrum; the position 
of the bands varying according to the nature of the solvent. 


Fic. 34. Spectra of the pigments of Coenopsammia willeyi. 
1. Alcohol extract of the dried coral. 2. Alcohol extract of the decalcified coral. 
The coral was now decalcified by means of hydrochloric acid, at first of the strength 
maate oh of 1 to 4; afterwards the strong acid was added, from time to time, as required. 
pee ceceieiaed When the lime-salts had been dissolyed the soft brownish residue was washed 
with water until free from acid, on the filter paper. The wash water had a 
yellowish colour but showed no bands. The brownish acid-free pigmented substance itself 
gave no bands and was therefore free from polyperythrin. 
The brown decalcified substance was then treated with absolute alcohol which soon 
assumed a deep yellow colour and had a red fluorescence, and showed the same chlorophylloid 
spectrum as the alcohol solution of the dried (undecalcified) coral itself. The solution showed 
four bands of which three read:—Ist, 1672 to 2639, including shadings, dark from 2670 to 
2 650°5, 2nd about 7616 to 7595, and 3rd about 7545 to X531. So that here the chloro- 
phylloid pigment occurs united with lime-salts, and no lipochrome could be detected. 
Those portions of pigment of the decalcified corallum which were insoluble in alcohol 
BP inn of were treated with caustic soda (weak). The solution on filtermg had a reddish 
pigment in brown colour, but showed no bands, and absorbed the violet end of the 
ey spectrum. The addition of hydrochloric acid to this caustic soda solution causes 
partial precipitation of this pigment, and after filtermg a brownish pigment is obtained. 
It is insoluble in ether, chloroform, alcohol, water or water acidulated with hydrochloric acid, 
but soluble in weak aqueous solution of caustic soda. 
This pigment is evidently the main cause of the colour of the coral. 
