Schunck . — The Chemistry of Chlorophyll . 93 
tartaric acid, ferrous oxide and tartaric acid. Such of these 
compounds as do exist have a number of properties in common, 
though the several classes differ inter se in some important 
particulars. They all dissolve — after having been precipitated 
by water from the solutions in which they were formed — 
more or less easily in alcohol, ether, chloroform, benzol, and 
carbon disulphide ; the phyllocyanin manganese acetate differs 
from the others in being soluble in water. The solutions have 
a colour varying from grass-green to a fine bluish-green, and 
they show peculiar spectra. The solutions remain quite un- 
changed when sulphuretted hydrogen is passed through them; 
no precipitate is formed, and on evaporation the various com- 
pounds are left behind with their original properties unaltered. 
It is only on incineration that the presence of the metallic 
constituent is detected, the copper compounds leaving, after 
being burnt, cupric oxide, the zinc compounds zinc oxide, the 
iron compounds ferric oxide. They all dissolve in dilute 
alkaline lyes, and are re-precipitated unchanged on the ad- 
dition of acetic acid. Of these compounds the zincic group 
is perhaps the most interesting in consequence of the striking 
resemblance which they show as regards some of their properties 
to chlorophyll itself. These compounds yield bright green, 
strongly fluorescent solutions, which show an absorption-spec- 
trum very like that of chlorophyll as regards the number and 
relative intensity of the bands ; the colour of these solutions 
soon disappears on exposure to light, though it is more perma- 
nent than that of a chlorophyll solution of the same intensity 
of tint. The zinc compounds are easily decomposed by hydro- 
chloric acid, phyllocyanin being at once reproduced. Zinc 
oxide is the only oxide which yields a compound with car- 
bonic acid and phyllocyanin ; the compound is dark green 
and semi-crystalline, and may be heated to 1 50° C. without 
decomposition. On adding hydrochloric acid to an alcoholic 
solution of phyllocyanin zinc carbonate and heating, bubbles 
of gas are seen to escape, the colour of the solution changes 
to blue, and on now adding water, there is a dark flocculent 
precipitate which dissolves easily on shaking up with ether, 
