" This ascription is very true, as I have more than once proved.

Some reader, who may be a chemist, will possibly, at his leisure, communicate an explanation of the process of this change.

Sphceria {raxinea is a communica- tion from Electricus, respecting some phenomena attending SphaeViaraxinea.

This plant, which is the Hypoxylon con- centricum of Grevilles Cryptogamic Flora, t 324, but after- wards, in his Synopsis Generum el Specierum, called SphaeVia concentrica, is tolerably frequent, but not common, in this neighbourhood.

I last year obtained several specimens ; and, although I then observed the phenomenon alluded to, I did not make any particular remarks upon the subject; but on Saturday evening last I brought home two specimens, and placed them on the mantel-piece, and on the following morn- ing they were covered and surrounded by the black powder, as correctly described by Electricus.