Tinctura Pyrethri (Tr. Pyreth.), Tincture of Pyrethrum, U.S.P. (Tincture of Pellitory).—Pyrethrum (20%) in alcohol. Absolute alcohol content about 90 per cent.
Uses: External.
Pyrogallol (Pyrogall.), Pyrogallol, U.S.P. (Pyrogallic Acid).—Trihydroxybenzene.
Light, white or nearly white, odorless, bitter laminae, fine needles or powder. Freely soluble in water (1:1.7) and in alcohol (1:1.3).
Action and Uses: Irritant antiseptic in chronic skin diseases. Internally highly toxic.
Dosage: 5 per cent. ointment.
Pyroxylinum (Pyroxylin.), Pyroxylin, U.S.P. (Soluble Gun Cotton).—Chiefly cellulose tetranitrate.
A yellowish-white matted mass of filaments, resembling raw cotton in appearance; very inflammable. Slowly but completely soluble in a mixture of three volumes of ether and one volume of alcohol. Also soluble in acetone and in glacial acetic acid. Practically insoluble in alcohol or water.
Action and Uses: Basis for collodions.