233 
of Chlorophyll . 
calls 4 chlorophyll-green/ and which according to him is 
the colouring-matter in a state of purity. Having myself 
paid some attention to the action of alkalis on chlorophyll, 
I have come to the conclusion that Hansen’s process, in 
which caustic alkali plays a part, leads to a product which 
cannot be considered as unchanged chlorophyll, and I shall 
therefore defer what I have to say about it until I come 
to the derivatives of chlorophyll. 
The elaborate paper of Professor W. N. Hartley, entitled 
4 The Spectra of Blue and Yellow Chlorophyll, with some 
observations on Leaf-green V is chiefly devoted to a cor- 
rection of the chlorophyll-spectrum as described and figured 
by previous observers. The author distinguishes blue choro- 
phyll and yellow chlorophyll. The former corresponds to 
the ordinary chlorophyll of most authors, the latter to what 
has been called at various times xanthophyll, chrysophyll, 
or erythrophylJ. The solutions of blue chlorophyll show 
two narrow bands close together in the red, usually represented 
as one. This splitting up of the band in the red may have 
been due to the use of barium hydrate in the preparation of 
the substance. According to Chautard. solutions of chorophyll 
on the addition of caustic alkali show two bands in the red 
in place of one. On the other hand, Professor Hartley states 
that by using neutral solvents, such as benzene, he obtained 
a blue chorophyll identical so far as the spectrum was con 
cerned with the other. The two colouring-matters of Professor 
Hartley, it should be observed, are not identical with the blue 
and yellow chlorophyll of Stokes and Sorby. The latter con- 
stitute together what may be called green chlorophyll, the 
terms blue and yellow being of course merely relative ; they 
are separated by the use of various neutral solvents and closely 
resemble one another ; blue chlorophyll, however, by decom- 
position with acids yields phyllocyanin, whereas yellow chloro- 
phyll gives phylloxanthin, as I shall have again occasion to 
mention. 
Timiriazeff 2 obtains from chlorophyll, by reducing agents 
1 Journ. of the Chem. Soc. lix. io 6. 2 Comptes Rendus, cix. 414. 
