No. II.—Remarks on a peculiar Colouring Matter in Decayed Wood.
By W. C. Trevelyan, Esq., of Wallington.
Read, July 19, 1831.
I have lately been engaged in some experiments on the colouring matter of the decayed wood on which Peziza æruginosa (well represented in Greville's Cryptogamic Flora, t. 241) generally occurs. It is often to a considerable depth of the same beautiful green colour as that remarkable Fungus, and frequently when none of that plant appears upon it, so that I should think that this colour is derived from a peculiar matter unconnected with the Peziza.
I find that it is most readily soluble in nitric acid, which soon acquires a deep emerald-green colour from a small portion of the wood. When evaporated a sap-green deposit is left, consisting of the colouring matter, and some earthy matter from which it may be separated by alcohol or ether; the latter after exposure to the flame of a blow pipe, exhibits alkaline qualities, turning the vegetable blues, green.
If a larger quantity of the solution is exposed for a length of time to a low heat the colour gradually disappears, and if allowed to stand, crystals of oxalic acid appear.
Chlorine and muriatic acid have no effect on the solution in nitric acid, but destroy the colour of the wood.
Alcohol and ether acquire a green colour, gradually changing to a brownish red from the wood, which, also, when immersed in them, becomes of the same colour, but the green is restored by nitric acid. A solution of a brown colour is obtained by the action of alkalis on the wood; they give also the same colour to the solutions in nitric acid, and in alcohol, and to paper stained by these solutions, the original colour is restored by nitric, muriatic, sulphuric, tartaric, acetic, and
