236 Schunck.— The Chemistry 
action of acids on chlorophyll. I there said that by de- 
composition with acids chlorophyll yields two coloured 
products — phyllocyanin and phylloxanthin. Of the former 
I gave a detailed description. The latter has since then been 
more minutely examined, the results being contained in a 
paper read before the Royal Society in June 1891 1 . Phyl- 
loxanthin is there defined as the ‘ product formed along with 
phyllocyanin by the action of strong acids on chlorophyll and 
left dissolved in ether when concentrated hydrochloric acid 
is added to an ethereal solution of the two substances, the 
phyllocyanin passing into the acid.’ It is necessary to adhere 
strictly to this definition, in order to avoid confusion, the term 
phylloxanthin having been applied to more than one sub- 
stance. The phylloxanthin of Fremy is a mixture of several 
colouring-matters, true phylloxanthin as just defined forming 
only one constituent of the mixture. Although the quantity 
of this substance formed by the decomposition of chlorophyll 
with acids is much larger than that of the phyllocyanin 
accompanying it, its preparation in a state of purity is much 
more difficult, and the product even at the best is never 
free from impurities of a fatty nature. An account of the 
mode of purification will be found in the paper referred to. 
The properties of phylloxanthin resemble those of phyl- 
locyanin so closely as to lead to the conclusion that the two 
substances must be nearly related, that they are perhaps 
isomeric bodies ; the attempts made to convert one into the 
other were however unsuccessful. 
When dry, phylloxanthin appears dark green, almost black, 
thus differing from phyllocyanin, which always shows a dark 
indigo-blue colour. It is amorphous, even under the micro- 
scope, though it may occasionally be obtained by very slow 
evaporation of its ethereal solution in small rosettes which 
are rust- coloured by transmitted light. When a very minute 
portion is placed on a glass slide, then moistened with ether 
under a cover-glass, it is seen to resolve itself under the 
microscope into a number of long whip-like filaments and 
1 Proc. Roy. Soc.-vol. 1. p. 302. 
