P. (Bole'tus) fomenta'rius, Agaric of the Oak (Touch Wood). -- The fungus, U.S.P. 1830; Europe, on Quercus and Fagus species. It is formed by an additional layer of fibers each year; is collected Aug-Sept., and resembles the horse's hoof, being 15-25 Cm. (6-10') wide. When young is soft, velvety, but becomes hard and ligneous; when deprived of outside ligneous portion, brownish above and yellowish-white beneath, porous, fibrous, tough, inodorous, tasteless; when for use is deprived of harder rind, sliced, boiled in lye, washed, beaten, until soft and pliable, then absorbs twice its weight of water; contains extractive, resin, nitrogenous matter, KCl, CaSO4; the ash -- Fe, Ca, Mg, phosphate. Used locally with pressure to arrest hemorrhage. Agaric steeped in nitre solution yields spunk or tinder.