Chap. VIII. 



GREEN INDIGO. 



165 



colour, having a strong analogy with that of Java indigo, 

 but of a finer cake, and differing besides from indigo both 

 in its composition and in all its chemical properties. On 

 infusing a small fragment of the substance in water, the 

 liquid speedily became coloured of a deep blue, with a 

 shade of green. After the temperature had been raised to 

 the boiling point, a piece of calico, prepared for printing 

 with mordants of alum and oxide of iron, was dipped in it, 

 and a true dye was the result. The following appearances 

 were observed : — 



The portions of the fabric to which alum had been 

 applied showed a deep green, of more or less intensity, 

 according to the strength of the mordant. 



The portions charged with both alum and oxide of iron 

 yielded a deep green, with a shade of olive. 



The portions charged with oxide of iron alone yielded a 

 deep olive. 



The parts of the cloth where no mordant had been 

 applied remained sensibly paler. 



The colom's thus obtained were treated with all the 

 reagents to which the Chinese calico had in the fii'st in- 

 stance been subjected, and they behaved in precisely the 

 same manner. From these experiments it may be in- 

 ferred, — 



1st. That the Cliinese possess a dye-stuff presenting the 

 physical aspect of indigo, which dies green with mordants 

 of alum and iron. 



2nd. That this dye-stuff contains neither indigo nor 

 anytliing derived from that dyeing principle. 



Mons. Legentil, President of the Chamber of Commerce 

 of Paris, having perceived the importance of France being 

 speedily put in possession of this valuable material, with a 

 view to the interests of science and of industry, took the 

 necessary steps several months ago for procuring a suitable 

 quantity with the least possible delay, and, at the same 

 time, to have inquiries made as to its origin and mode of 

 preparation. 



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