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Mr. E. Schunck. 



yielding bright green solutions, which he took to be regenerated 

 chlorophyll. Tschirch acted on Hoppe-Seyler's chlorophyllan with 

 zinc powder, and observed the same phenomenon, the conclusion at 

 which he arrived being the same, viz., that chlorophyll is reproduced 

 from chlorophyllan by the reducing action of zinc. I think, however, 

 that what Tschirch obtained was, in reality, a zinc compound, and 

 would have been formed just as well by using zinc oxide. Chloro- 

 phyllan is probably an impure substance, containing, it may be, some 

 fatty acid, together with phyllocyanin, so that by the action of zinc 

 oxide on the mixture a compound similar to those above described 

 may be formed. 



I have tried the experiment with the precipitate produced by treat- 

 ing a chlorophyll solution with hydrochloric acid, which probably 

 differs very little from chlorophyllan, dissolving it in boiling alcohol, 

 adding zinc oxide and boiling for some time, when a bright green 

 liquid was obtained, which might have been taken for a solution of 

 chlorophyll, but evidently contained a zinc compound of the same 

 character as those formed directly from phyllocyanin by a similar 

 process. The spectrum was identical with that of the zinc compounds 

 from phyllocyanin. 



The ferrous group of compounds yield solutions of a pure green, 

 like that of chlorophyll. They are not, however, strikingly fluo- 

 rescent, and when exposed to sunlight in open vessels they retain 

 their colour unchanged for a long time. The group may be divided 

 into two sub-groups : the first sub-group comprising compounds 

 into which one of the fatty acids — acetic, palmitic, or oleic acid — 

 enters as a constituent ; the other sub-group, such as are formed by 

 the action of citric, malic, or phosphoric acid. The members of the 

 first sub-group show, in solution, the same spectrum, consisting of 

 four ill-defined absorption bands, with much obscuration throughout. 

 To the other group belongs a spectrum consisting also of four bands, 

 which are, however, differently placed and more distinct than with 

 the first sub-group. If a small quantity of hydrochloric acid be 

 added to an alcoholic solution of any one of the iron compounds the 

 solution acquires a blue tint, and the bands are now found to have 

 shifted considerably towards the blue end. This effect may be due to 

 the removal of a portion of the iron, and the formation of compounds 

 with less iron. If a member of the second sub-group be taken, the 

 phosphate or the malate for instance, then on the addition of hydro- 

 chloric acid a spectrum is obtained which closely resembles the 

 ordinary chlorophyll spectrum as regards the number, position, and 

 relative strength of the bands. The members of the first sub-group 

 undergo a further change by treatment with an excess of hydro- 

 chloric acid and boiling, but the resulting product is not phyllo- 

 cyanin. 



