1899] CHEMISTRY OF OUR FOREST TREES 57 



splint-wood ; the wood-elements seem only very slowly to become 

 completely lignified, and although the ratio of " incrusting matter " 

 therein is ultimately extremely high, there exists only a very small 

 quantity of tannin and that only infiltrating the walls ; in the inner 

 rings there is a specially abundant store of starch laid up to meet the 

 tremendous drain of the " seed-year," this starch gradually changing 

 into drops of wood-gum (xylan). Moreover, it requires more nitrogen 

 than most other trees, and needs a plentiful supply of potash. The 

 external economy, too, is as remarkable as the internal. The cortex is 

 a veritable curiosity. " The whole tree," says Wicke, " sticks, so to 

 speak, in a siliceous coat of mail, the silica forming a thick solid crust 

 over the whole stem and the young twigs." The bark is said to con- 

 tain 70 to 90 per cent of oxalate of calcium. Beech leaves are 

 eminent for their large percentage of fatty matter, fibre, lime, silica, 

 and manganese. In view of the considerable amount (some 25 per 

 cent) of oil in the nut, the enormous affluence of starch, and the poor 2 

 per cent of tannin in bark and leaves, we can have no hesitation in pro- 

 nouncing the Beech to be the most vivaciously active and powerful 

 assimilating organism of our woodlands. Finally, how it happens that 

 the Spanish Chestnut should specifically and exclusively produce the 

 particular tannin called gallotannin in the bark and the wood (each 

 contains about 7*5 per cent, the leaves about 6 per cent), is one of the 

 mysteries shrouded beneath the impenetrable and inscrutable veil of 

 forest secrecy. 



Passing by the Hazel, Walnut, etc., which are not strictly speaking- 

 forest trees, we now approach a mystic tenant of the woods, a true 

 native, and abundantly familiar, but which challenges the utmost 

 possible chemical consideration that can be bestowed upon it. This 

 is the common Ash (Fraxinus excelsior), and no lynx-eyed acuteness is 

 requisite to enable anybody to perceive that even exteriorly it differs 

 immensely from its arboreal neighbours and confreres. The smooth 

 olive-grey bark, the astonishing knotty protuberances of its bursting 

 flower-buds in spring, the almost absolute freedom from any intrusive 

 or brilliant colorific effect in any of its members or organs, are so many 

 tokens and pledges of characteristics entirely uncommon. It is a 

 starch-tree, but its seeds contain 16 per cent of oil and no starch, and, 

 moreover, on analysis one finds in the various organs such a consider- 

 able amount of waxy, resinous, and fatty matter, and such evidences 

 of a facile decomposition of such carbohydrates as are produced in its 

 leaves, that its claim to enrolment in the order Oleaceae is seldom 

 questioned and never belied. In 1840 Gmelin had noticed a peculiar 

 iridescence among the constituents of the bark of Fraxinus Omus ; but 

 in 1856 Salm-Horstmar discovered a similar fluorescence in the 

 infusion of the bark of F. excelsior, and in the following year he 

 isolated, examined, and called it fraxin. Its dilute aqueous solution 

 exhibits by reflected daylight a strong blue or blue-green fluorescence 



