Characters and Tests. - Pale grey, amorphous, without smell, but, even in the most minute quantity, powerfully irritating the nostrils; strongly and persistently bitter, and highly acrid; insoluble in water, soluble in spirit, in ether, and in diluted acids, leaving traces of an insoluble brown resinoid matter. Heated with access of air, it melts into a yellow liquid, and at length burns away, leaving no residue. An active poison.
It has not been proved.
Preparation. - Solution in rectified spirit.