440 CHEMICAL DISCOVERY AND INVENTION 



chlorophyll can be extracted from green leaves without altering 

 it in some degree by the action of the solvents employed for the 

 purpose. Dr. Schunck of Manchester, more than twenty years 

 ago, supposed that he had succeeded in isolating pure chloro- 

 phyll, and he prepared from it a series of crystalline derivatives. 

 By the action of alcoholic potash he obtained a compound which 

 he called phyllotaonine and a derivative of this named phyllo- 

 porphyrin. The latter was found to have an absorption spec- 

 trum nearly allied to that of hsemoporphyrin, a derivative of 

 the colouring matter of blood. In these researches he was joined 

 by the Polish professor, Marchlewski. The formula they pro- 

 posed was, however, not confirmed by the later researches of 

 Willstatter, to whom we owe the greater part of the knowledge 

 we now possess of the composition and products of decomposi- 

 tion of this important substance. 



Chlorophyll is a salt containing magnesium, and it is repre- 

 sented by the rather complex formula C 55 H 72 5 N 4 Mg. 



Chlorophyll as it exists in the plant is an amorphous substance, 

 the crystalline chlorophyll which has been described being now 

 known to be a product of decomposition. Chlorophyll is the 

 methylphytol ester of a tribasic acid to which the name chloro- 

 phyllin has been given with the formula : 



( CO-OH 



C 31 H 29 N 3 Mg J CO-OH 

 [ CO'NH 



The full formula of chlorophyll is therefore : 



( CO-OCH 3 



C 8 iH 89 N 8 Mg \ CO-OC 20 H 39 

 ( CO-NH 



Phytol is an unsaturated alcohol, C 20 H 39 OH, which in the 

 isolated state is a colourless oil which boils at a high temperature, 

 and any attempt to distil it, except in a vacuum, leads to its 

 destruction. 



The colour appears to be connected with the complex nitro- 

 genous nucleus, and the magnesium is supposed to be united in 

 a peculiar manner with the four nitrogen atoms. Treatment of 

 chlorophyll with alkaline reagents fails to disturb the magnesium, 

 but it is extracted and removed by the action of acid liquids. 

 The nitrogen atoms are believed to exist in the molecule of 



