This section is from the book "An Experimental History Of The Materia Medica", by William Lewis.
Moxa five lanugo artemisia japonicae Pharm. Paris, Moxa: a soft lanuginous substance, prepared in Japan, from the young leaves of a species of mugwort, by beating them, when thoroughly dried, and rubbing them betwixt the hands, till only the fine fibres are left. A like substance is said, in the German epheme-rides, to have been obtained, by treating the leaves of our common mugwort in the same manner.
Moxa is celebrated in the eastern countries, for preventing and curing many disorders, by being burnt on the skin: a little cone of moxa, laid on the part previously moistened, and set on fire at top, burns down with a temperate glowing heat, and produces a dark coloured spot, the exulceration of which is promoted by applying a little garlic, and the ulcer either healed up when the eschar separates, or kept running for a length of time, as different cir-cumstances may require. A fungous substance, found in fissures of old birch trees, is said to be in common use among the Laplanders for the same purposes (a); and some have used cotton, impregnated with a solution of nitre, and afterwards dried, which answers the end as effectually as the moxa of the Japonese (b). It is obvious, that all these applications are no other than means of producing an exulceration of the skin, and its consequence a drain of humours.
(a) Philosoph. Transact. No. 474.