38 Transactions of the 



being quite strong enoiigh. Ammonia, potash, or the car- 

 bonated alkalies may be nsed in lieu of caustic soda. The 

 mass is stiiTed at intervals for fifteen minutes, or there- 

 abouts ; the crimson solution is poured off and pure water 

 added ; by successive treatment of the barbs with fresh por- 

 tions of dilute alkali and pure water, the whole of the crimson 

 pigment is obtained in solution, the residual barbs becoming 

 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 

 mixuig one part of the pure commercial acid with four parts 

 of water. When the red precipitate of the pigment thus co- 

 agulated 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 

 colourless, until there is no longer a trace of acid left in the 

 pigment on the filter. When this occurs, the residue is 

 washed off with water containing a few drops of acetic acid 

 to the pint, and then s}Tinged out of the filter into an 

 evaporating basin and dried at a gentle heat. The dry pig- 

 ment 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 crys- 

 talline form. It is very slightly soluble in jjure water, 

 giving a pale rose-pink solution. The presence of acids and 

 salts renders water incapable 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 pigment. In fact, Turacin is a very 

 delicate test for the allcalies. 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 solu- 

 tions 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 



