MR. A. H. CHURCH ON TURACIN, AN ANIMAL PIGMENT CONTAINING COPPER. 629 
which have either a crimson blotch upon them, or are almost wholly coloured. I pro- 
pose the name Turacinfor the red pigment which the Touracou ( Turacus ) contains. In 
order to extract this pigment the plan finally adopted was as follows : — 
Isolation of Turacin . — The barbs constituting the red part of the web are stripped 
from the shaft of the feathers, placed in a beaker, and washed with ether and then with 
alcohol. This treatment removes the grease and adhering dirt very effectually. When 
the red barbs thus washed have been dried between folds of filter-paper, they are placed 
in a cold very dilute solution of pure caustic soda, a solution containing one part of soda 
in a thousand of distilled water being quite strong enough. Ammonia, potash, or the 
carbonated alkalies may be used in lieu of caustic soda. The mass is stirred at intervals 
for fifteen minutes, or thereabouts ; the crimson solution is poured off and pure water 
added ; by successive treatment of the barbs with fresh portions of dilute alkali and pure 
water, the whole of the crimson pigment is obtained in solution, the residual barbs be- 
coming white or pinky grey. All the coloured liquors having been filtered and mixed, 
they are poured in a slender stream, with constant stirring, into dilute hydrochloric acid, 
made by mixing one part of the pure commercial acid with four parts of water. When 
the red precipitate of the pigment thus coagulated and rendered insoluble has settled, 
the supernatant liquid is decanted off and the red matter thrown upon a wetted filter 
and washed with water. (A still better plan is to employ a decanting siphon filter for 
the separation and washing of the precipitate.) The liquid comes through quite colour- 
less, until there is no longer a trace of acid left in the pigment on the filter. When 
this occurs, the residue is washed with water containing a few drops of acetic acid to the 
pint, and then syringed out of the filter into an evaporating-basin and dried at a gentle 
heat. The dry pigment is next to be washed with a mixture of alcohol and ether, and 
once more dried. It is now perfectly pure and yet unchanged, so far as I have examined it. 
Properties of Turacin . — Prepared as above described, turacin occurs in scales which 
have a deep violet-purple colour by reflected light, and showing a crimson tint when 
seen in small fragments by transmitted light. Its powder is of a dull crimson tint. It 
has not been obtained in a crystalline form. It is very slightly soluble in pure water, 
giving a pale rose-pink solution. The presence of acids and salts renders water inca- 
pable of dissolving it. It is not soluble in pure alcohol or ether. In alkaline liquids it 
immediately dissolves, forming solutions which show a bluer tint than the original pig- 
ment. In fact turacin is a very delicate test for the alkalies. For example, perfectly 
pure barium hydrate in solution does not dissolve turacin ; but let a minute trace of soda 
exist, as it often does, in the baryta-solution, and then the liquid will become readily 
tinted if shaken up with a fragment of turacin. Very strong solutions of the caustic 
alkalies dissolve the pigment, but at the same time it suffers a partial decomposition, 
evidenced by an odour resembling that of certain bases of the pyridine series, which it 
then evolves. Fuming nitric acid dissolves it with a deep brown tint, destroying it ; in 
oil of vitriol it is soluble, but in all probability with partial alteration. Turacin seems 
to have slightly acid properties ; though it dissolves very freely in carbonated alkalies, 
mdccclxix. 4 P 
