BLUE PIGMENT IN COKAL AND OTHER ANIMAL ORGANISMS. 263 



Tartaric Acid. — A faint blue colour on boiling. 



Oxalic Acid. — Insoluble. 



Citric Acid. — Yields a pale blue solution on boiling. 



4. Alkalis. — In cold dilute ammonia it gives a pale blue solution 

 which gradually fades in the course of a few weeks. It is much 

 more soluble in strong ammonia, also in hot ammonia. On 

 evaporating to dryness the residue is of a brownish colour. 



It imparts a greenish colour to potash, both dilute and strong 

 solutions, but when boiled with potash the solution turns brown. 

 Moseley states that the colour is restored by acids, but I did not 

 find this to be the case; a very faint dusky purple only was obtained. 

 When boiled with ammonium, sodium and potassium carbonates, 

 it in each case yields a dingy slate coloured solution with a slight 

 purple tinge. 



Aromatic derivatives. — It is insoluble in benzene. Nitro- 

 benzene is coloured green by it, but on heating this darkens and 

 becomes brown. It also imparts a greenish tint to colourless 

 phenol in the cold; on heating it yields a dark solution — the 

 pigment does not, like indigo, appear to be redeposited on cooling. 

 On evaporating down to dryness over a water bath and driving 

 off the phenol, the pigment was left as a sap-green resinous-look- 

 ing film, which under the microscope was seen to be made up of 

 drop-like forms without any trace of crystallisation. 



It appears to be insoluble in xylenol and also in aniline. 



It is partly soluble in cresol (meta) to a dark green solution, 

 and in cold creosote to a pale green, in hot creosote it yields a 

 dark green solution similar to cresol. 



The phenol, cresol, xylenol, aniline and other similar solutions 

 were filtered through glass wool and evaporated but none of them 

 deposited the pigment in a crystalline form. 



Salts. — It was found that the pigment is insoluble in sodium 

 chloride and nitrate, both in the cold and when boiled. The 

 acetate of sodium gave a slight shade of green, and the phosphate 



