127 
facts, that the matter which gives rise to the green 
colour of plants (359.) resides principally in the 
juices of their leaves; if these juices, when extracted 
by water or alcohol, exhibit, in various instances, yel- 
low, brown, red and green colours (368. et seq.), ac- 
cording to the proportion of acid or alkaline matter 
which they may contain ; and if, farther, the entire 
leaves themselves (374. 5.) exhibit similar changes of 
colour when exposed to the operation of the same 
agents ; may we not reasonably presume, that these 
same agents, if present, will exert a similar action on 
the leaves during their growth ? Let us then inquire 
whether the actual condition of green and of white 
leaves authorises us to conclude that they possess 
corresponding proportions of alkaline and acid mat- 
ter. 
377. With respect to green leaves, it is known, 
that these, and other green parts, afford alkali in much 
larger quantity than any other parts of the plant. 
From a report made to their government by the 
French chemists, it appears, that herbaceous plants 
afford five times more ashes than large trees, and that 
the leaves of trees yield more than their trunks *. 
Alkaline salts, says M. de Saussure, form, beyond 
comparison, the most abundant ingredient in the ashes 
of herbaceous plants. In many instances, the ashes 'of 
young leaves, growing on a bad soil, contained at least 
three-fourths of their weight of alkaline salts; the 
young leaves of trees also contained half, or some- 
times three-fourths, of their weight of these salts, but 
* Murray's oystem of Chemistry, vol. ii. p. 80. 1st edit.- 
