43 
On the Colouring Matters of Blue Decayed Wood. By 
H. C. Sorby, F.R.S. 
Decayed wood, coloured blue by the spawn of Peziza 
cerugnosa (see ‘ Quart. Journ. of Science/ V, 222) contains 
several colouring matters. None of these are sensibly solu- 
ble in water, but they are dissolved by alcohol with varying 
facility, so that they may be separated with a little care. On 
digesting with the aid of heat a portion of the wood in a 
moderate quantity of alcohol, a solution of dull neutral tint 
is obtained, and the wood is left of a bluer green. On agi- 
tating the alcoholic solution with bisulphide of carbon, that 
liquid abstracts a small quantity of a yellow colour, which 
does not present any facts of particular interest. The alco- 
holic solution is a mixture of a claret colour, very easily 
dissolved by alcohol, and a blue, soluble with much greater 
difficulty, so that, on evaporating to dryness and redissolving 
in a little alcohol, the blue colour is left and the claret dis- 
solved, which may be still further purified by evaporating to 
dryness and redissolving a second time. It is then of a 
decided claret colour, with no trace of blue or green, and the 
spectrum shows a strong absorption at the blue end, gradually 
becoming less towards the red. Adopting the scale and 
nomenclature described in my paper in the ‘ Proceedings of 
the Royal Society/ 1 the spectrum is about 3f...9 11 — . 
The addition of a little ammonia turns it green, and deve- 
lops an absorption band in the orange, the centre being at 3. 
Citric acid restores it to the original state, unless so much 
ammonia has been added as to produce decomposition. Sul- 
phite of soda has no effect on an acid solution, so that the 
colour may be described as C al 0 anq (3). I have not yet met 
I with such a colour in any ^>ther substance. 
The blue colour may be obtained in greater purity by 
digesting the wood several times in fresh alcohol, so as to 
remove all the claret colour, when at length a clear blue- 
i green solution is obtained, which, however, is only pale. The 
spectrum, as seen in a tube two inches long, shows a well- 
marked absorption band in the red at 1/, with a small 
amount of the extreme blue partially obscured. On adding 
ammonia the colour is changed to a dull yellow, and the band 
removed ; but it is evidently decomposed, since citric acid 
does not restore it to the former state. A small quantity of 
nitric acid added to the original only serves to make it a 
1 1867, xv, 433. 
