260 A. LIVERSIDGE. 



The spectrum of the coral blue in glacial acetic, formic and 

 lactic acids and alcohol is mainly blue and green, a little of the 

 extreme red is visible and some of the yellow, but the bands are 

 by no means well denned. 



Solutions in glacial acetic acid when diluted gradually fade 

 and a voluminous whitish nocculent precipitate of organic matter 

 is formed, which on ignition burns with a nitrogenous odour. 



The undiluted solutions in glacial acetic, in strong formic and 

 propionic acids faded very slowly, and did not become turbid 

 even after standing some six months. The strong solutions of 

 the pigment when exposed to the light do not fade so quickly as 

 those of sulphindigotic acid and of indigo in glacial acetic acid. 

 To test this, solutions of equal depth of colour were made and 

 left exposed to diffused daylight; the indigo solutions faded and 

 lost the blue tint in a day or two, and after a week or two became 

 practically colourless, while the coral blue solution had faded 

 but slightly. A faded solution of indigo in glacial acetic acid is 

 quite red (salmon colour) by gas-light. 



The alcoholic solution fades more quickly than the acetio and 

 formic acid solutions, and especially when diluted ; a nocculent 

 precipitate is gradually formed and the solution turns brown ; 

 finally after two or three weeks it becomes colourless. 



The best solvents for the pigment were found to be formic acid, 

 hot glacial acetic and lactic acids and absolute alcohol. 



The acetic acid solution does not dye wool, silk or cotton, 

 neither is it fixed by alum or ammonia. 



It yields a very pale bluish-lake with alum and ammonia, but 

 the colour fades in a few days. It also yields precipitates with 

 baryta and lime waters, also with lead acetate; these precipitates 

 require further examination. 



Action of Reagents. 

 1. Alcohols and their Derivatives. — The crude pigment set free 

 by hydrochloric acid is insoluble in methyl alcohol, also in ordinary 

 alcohol, although soluble in absolute alcohol; it is insoluble in cold 



