Sir D^VID BREWSTER on the Colours of Natural Bodies. 541 



At a certain thickness of the green fluid there are three red 

 bands. By increasing the thickness, the violet and blue spaces 

 are absorbed, and the two inner red bands. An absorption then 

 begins near the middle of the green space, and after destroying 

 the more refrangible portion of that space, three bands are left ; 

 viz. one faint band of the extreme red, one band almost white, 

 corresponding with the most luminous spectrum, and one green 

 band contiguous to the white one. 



The general effect of the absorption now described is shewn 

 rudely in the second of the accompanying figures, the first of 

 which represents the effect which would have been produced had 

 the colour been a phenomenon of thin plates, and a green of the 

 third order. The simple inspection of Figure 2. affords the most 

 unquestionable evidence that the green colour under considera- 

 tion is neither the green of the third order nor of any other order 

 of periodical colours, and that in its general character, as well as 

 in the character of its component bands, it has no resemblance 

 whatever to any colour produced by the action of thin plates. 



In applying this mode of examination to the green colours 

 of other plants, I have found them to have invariably the same 

 composition. In the following list of plants of various charac- 

 ters, I have given those in which I have made the experiments 

 with most care. Excepting where it is otherwise mentioned, 

 the green fluid was extracted from the leaves : 



White Lilac. White Jasmine. Aucuba Japonica. 



Convolvulus. Thuja occidentalis. Juniperus communis. 



Tulip-Tree. Arbutus Unedo. Camellia Japonica. 



Mignionette. Hemerocallis flava. The green berries of the 



Common Pea. Celastrus scandens. Convallaria multiflora. 



Daphne Cneorum. Viburnum Tinus. The green berries of the 



Virginian Raspberry. Primus Lusitanica. Asparagus officinalis. 



When the green fluid obtained from these plants has stood 

 for three or four days, it loses its high green colour, and becomes 



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