540 SUMMARY OF CURRENT RESEARCHES RELATING TO 



then, to avoid misconception when using the term chlorophyll, means 

 simply the substance, or it may be mixture of substances, to which the 

 pure green colour of ordinarily healthy leaves and other vegetable 

 organs is due. The various attempts to isolate chlorophyll are then 

 described. Berzelius, Mulder, Morot, and Fremy all employed pro- 

 cesses for preparing chlorophyll involving the use of hydrochloric 

 acid, and really obtained products resulting from its decomposition. 

 M. Gautier prepared chlorophyll with neutral solvents, and obtained a 

 substance in distinct crystals of an intense green colour ; this product, 

 as well as Hoppe-Seyler's chlorophyllan, are probably derivatives of 

 chlorophyll. The product obtained by Hansen, chlorophyll-green, is 

 however a sodium compound, and the author's conclusion is that chloro- 

 phyll has not yet been obtained in such a state of purity as to allow of 

 its physical and chemical properties being described. Most observers 

 agree in stating that chlorophyll is insoluble in water and soluble in 

 ether, chloroform, carbon. disulj)hide, ethereal and fatty oils, and similar 

 substances. That iron in some form or other is an essential constituent 

 of chlorophyll, has been repeatedly asserted and as often denied ; the 

 author is of the opinion that it is not. 



The absorption-spectrum of chlorophyll presents several points of 

 controversy, especially the broad indistinct bands at the blue end of the 

 ordinary chlorophyll-spectrum, which are only seen by sunlight, and are 

 distinguished as bands V. and VI. (German notation). Some observers 

 consider these as true chlorophyll-bands, while others are of opinion that 

 they belong to a yellow colouring matter accompanying chlorophyll 

 called xanthophyll. The author takes this latter view, seeing that it is 

 possible to isolate a colouring matter from leaves in regular lustrous 

 crystals, which gives yellow solutions showing two distinct bands in 

 the blue when sufficiently dilute, but no bands whatever in the red, 

 yellow, or green, however concentrated they may be. 



Dr. Schunck then describes the products formed in the processes of 

 decomposition to which chloroj)hyll has been hitherto submitted. By 

 the combined action of ether and hydrochloric acid, Fremy obtained two 

 colouring matters, a blue and a yellow ; these he named phyllocyanin 

 and phylloxanthin. Phyllocyanin is one of the most important deriva- 

 tives of chlorophyll, its properties being very interesting. When dry 

 it has the appearance of a dark-blue mass, which, when examined under 

 the Microscope, is found to consist almost entirely of elongated rhom- 

 boidal or irregularly six-sided crystalline plates, which are generally 

 opaque, but, when very thin, are translucent, and then appear olive- 

 coloured by transmitted light. Phylloxanthin is the product obtained 

 by dissolving the precipitate formed by acids in an alcoholic extract of 

 leaves in ether, and adding concentrated hydrochloric acid to remove the 

 phyllocyanin, where it remains dissolved in the upper ethereal liquid. 

 Solutions of phylloxanthin have a yellowish-green colour, with a pro- 

 nounced reddish tinge, and may be thereby distinguished from solutions 

 of phyllocyanin, which are more decidedly green. They show a spec- 

 trum of four bands only, that of phyllocyanin having five ; an admixture 

 of the latter v, ith phylloxanthin may therefore be easily detected. 



Dr. Schunck then describes the various compounds of phyllocyanin, 

 and also the action of alkalies on chlorophyll, which has been less fre- 

 quently studied than that of acids, partly perhaps because alkalies do not 

 produce such marked changes as acids. One of the most interesting 



