On the Colour of Leaves of Plants and their Autumnal Changes

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                                of sodium changed the colour of the partially dried solution 
to blue and then to deep green; when quite dried, to a rich 
amber at the outer edge, and elsewhere to a decidedly reddish 
brown tint. Under the microscope both red and yellow colours 
were seen, but not a trace of green. These curious changes 
admit of the following explanation; the intensification of the red colour 
was due to the action of the acid; the green colour was produced 
by the potash and soda rendering the yellow colouring matter 
soluble and thus allowing the yellow and the red, or rather 
<u>blue <\u> colours, to come together and so form the green. The further 
change to yellow was in part produced by the decomposition of the 
chlorophyll into the yellow and red pigments and the 
subsequent incorporation of the latter with the former colour.
Indeed, the yellow colouring matter seems to possess such a 
capacity for the absorption of the red as to render this in 
some cases invisible. If the proportion of red be much greater 
than the yellow, then this becomes of a deeper tint and 
sometimes even reddish, so that the admixture of the two 
colours can be detected with the lens or even by the eye alone.
The alcoholic solution obtained from the chocolate coloured
leaves of <s>the <\s> an ivy geranium presented much the same character 
as the above. The solution when poured into a watch glass 
was almost colourless, but the next morning the <s>evaporated <\s> dried 
residue was found to be of a lovely deep pink colour; this 
under the microscope was seen to consist mainly of a clear,
non-granular and diffused pink colouring matter, surrounded 
near the outer edge of the deposit by a number of bright yellow 
granules of irregular size and shape, these being in marked contrast 
                            
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Manuscript details

Author
Arthur Hill Hassall
Reference
AP/69/1
Series
AP
Date
1892
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On the Colour of Leaves of Plants and their Autumnal Changes, 1892. From The Royal Society, AP/69/1

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