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Mr. E. Schunck. 



[Dec. 20, 



stable when in contact with acids. The third class consists of 

 glucosides, bodies which do not undergo any considerable change 

 under the influence of alkalis, but are rapidly decomposed when acted 

 on by acids or ferments, yielding, on the one hand, some kind of 

 glucose, and, on the other, substances in which the tinctorial pro- 

 perties of the parent substance are much more pronounced. To this 

 division belong the colouring-matters of madder, quercitron, cochineal, 

 &c. Now chlorophyll in its general properties so much resembles 

 the members of the last class that one cannot help suspecting that to 

 this class it may belong— that it is in fact a glucoside. It shows con- 

 siderable stability in the presence of alkalis, but acids decompose it 

 rapidly, giving rise to substances which are intensely coloured and 

 show a power of absorbing particular parts of the spectrum much 

 more strongly than chlorophyll itself. Whether, along with the latter 

 bodies, it yields by decomposition with acids some kind of glucose, 

 seemed to me a question worthy of attention. 



If it was possible to obtain chlorophyll in a state of purity, it 

 would be very easy to settle this question ; unfortunately all attempts 

 hitherto made to separate and purify chlorophyll have ended in its 

 decomposition. I consider it as certain that the so-called crystallised 

 chlorophyll which has been described by several authors is in fact a 

 derivative of chlorophyll formed during the process employed for 

 preparing it. It is, however, very easy to obtain a solution of chloro- 

 phyll which shall be quite free from everything soluble in water 

 extracted at the same time from the plant, and therefore free from 

 ready-formed glucose. In order to effect this, I proceed as follows : — 

 Having extracted leaves of any kind with boiling alcohol, I allow the 

 extract to stand for some time, filter off the deposit which usually 

 forms, and then mix it with its own volume of ether and with about 

 two volumes of water, shaking up well. The liquid now separates 

 into two layers, an upper green one, containing all the chlorophyll 

 of the extract, and a lower bright yellow one, which contains tannin, 

 a yellow colouring-matter, a substance giving the glucose reaction 

 with Fehling's solution, and probably other substances besides. The 

 two liquids are separated in the usual way, and the upper one is 

 shaken up with fresh water, which now usually only shows a trace of 

 colour. This process of washing may be repeated, adding each time 

 a little fresh ether, until the lower layer ceases to give the glucose 

 reaction. The upper liquid leaves on spontaneous evaporation a bright 

 green residue, which, though far from being pure chlorophyll, is free 

 from everything soluble in water, and may therefore be employed to 

 determine whether anything soluble in water, such as glucose, is 

 formed by the action of acids on it. If some of the residue be 

 treated with concentrated sulphuric acid in the cold it dissolves, 

 forming a green solution, which, after standing for some time, gives, 



