1883.] 



Note on the Constitution of Chlorophyll. 



185 



011 the addition of water, a dark green precipitate. This precipitate 

 consists essentially of two snbstances, the phyllocyanin and phyllo- 

 xanthin of Fremy, which are undoubtedly products derived from 

 chlorophyll, showing the absorption bands of what is usually called 

 "acid chlorophyll." The liquid filtered from this precipitate, when 

 mixed with copper sulphate and an excess of caustic alkali, becomes 

 blue, and the mixture, on boiling, deposits cuprous oxide. The 

 experiment may be made in a slightly different manuer. The 

 residue left by the green ethereal solution of chlorophyll having been 

 dissolved in alcohol, sulphuric or hydrochloric acid is added to the 

 solution, which is then boiled for some time, evaporated so far as to 

 drive off most of the alcohol, filtered from the products insoluble in 

 water, made alkaline, then mixed with Fehling's solution and boiled, 

 when the usual glucose reaction takes place. In order to make sure 

 that the reaction was not due to ready-formed glucose, I took in every 

 case the precaution of testing a portion of the green chlorophyllic 

 residue with Fehling's solution before acting on the rest with acid. 

 This was easily done by treating with weak alcohol, to which a little 

 alcoholic potash and some Fehling's solution were added, and heating, 

 when the whole dissolved easily, giving a green solution, which, on 

 boiling, in no case deposited the least trace of cuprous oxide, whereas, 

 after adding an excess of hydrochloric acid to the liquid, boiling, 

 filtering off the insoluble products, again making alkaline and boiling, 

 the glucose reaction took place in a marked manner. 



This experiment has never in any case failed, and it would follow, 

 if uniformly successful, that the green leaves of all plants contain a 

 glucoside insoluble in water, but soluble in alcohol and ether. That 

 this glucoside is, in fact, chlorophyll seems to me highly probable. 

 Nevertheless , absolute certainty cannot be attained, because the matter 

 experimented on is a mixture, and it is possible that one plant out of 

 many might give a decidedly negative result, which would upset the 

 conclusion drawn from the rest. Assuming, however, that the pheno- 

 mena will always occur as above described, and that the reaction with 

 Fehling's solution indicates the presence of some kind of glucose, it 

 would follow either that chlorophyll is a glucoside, or that it is always 

 accompanied in the vegetable cell by a glucoside of very similar pro- 

 perties. 



I may add that I attempted to isolate the glucose or glucose-like 

 substance formed under the circumstances described, spinach leaven 

 being the material employed, and obtained a pale yellow gum-like 

 substance which showed no tendency to assume a crystalline form. 



