264 A. LIVERSIDGE. 



a hardly perceptible dusky purple tint. It is also insoluble in 

 magnesium sulphate and stannous chloride. On boiling with 

 stannic chloride a bright blue solution is apparently obtained, but 

 on filtering, most of the colour is left on the filter and a very 

 pale blue solution passes through. 



Other Reagents. — No colour was imparted to olive oil, and the 

 particles of pigment remained in it unbleached, although exposed 

 to the light for some months, but the olive oil became quite 

 colourless and viscid. It was found to be insoluble also in carbon 

 disulphide, carbon tetrachloride, chloropicrin, thiophen, oil of 

 cloves, cane sugar solution, etc. 



In all cases, although not always specifically stated, the reagent 

 was used hot as well as cold, and in most instances the cold 

 reagent was allowed to stand upon the pigment, with daily 

 shakings, for several weeks. 



It is bleached by chlorine water (the colour is not restored by 

 alkalis) and a greyish coloured residue is left (several other 

 reagents left a similar residue); this residue or skeleton burns 

 with a nitrogenous odour and leaves a considerable amount of ash 

 — it apparently consists largely of the membrane of the pigment 

 cells and perhaps cornein (C 30 H 44 N 9 O 13 ). The ash is ferruginous 

 in appearance and contains iron, phosphoric oxide, lime etc. 



A mixture of glucose, ferrous sulphate and lime does not appear 

 to reduce it as is the case with indigo. 



The colour is discharged by nascent hydrogen (from zinc and 

 hydrochloric acid) also by hydroxy], and sulphurous acid, and it is 

 not restored by neutralising with an alkali. 



After the above experiments were completed, the crude pigment 

 was obtained by means of hydrochloric acid from the growing 

 points of "live" coral, i.e., coral which had been gathered while 

 growing. 



The tips or growing points were of a dull slaty-blue colour both 

 externally and internally, and I expected them to yield a fuller 

 blue than the "dead" coral, but the pigment obtained was of a 



