CHAP. II. OF A PORRIGO.
We call that disorder a porrigo, scurf, when certain small scales arise amongst the hair, and are loosened from the skin; they are sometimes moist, much more frequently dry. It happens sometimes without any ulcer, sometimes in a part that is ulcerated, and is sometimes attended with a bad smell, sometimes with none. It usually occurs in the hair of the head, more rarely in the beard, sometimes also in the eye-brows. And as it never comes without some antecedent disorder in the body, so it is not altogether useless. For when the head is free from disorders, then it does not appear: when there is any disorder there, it is more expedient, in such a case, that the surface of the skin should be here and there corrupted, than that the noxious matter should be turned in upon a more noble part.
It is more proper then to cleanse it by frequent combing, than to repel it entirely. But if that method makes it more offensive (which may happen by the excessive discharge of humour, and more so, if the humour be fetid) the head is to be shaved often; and treated with some gentle repellents, such as nitre with vinegar, or labdanum with myrtle oil, and wine, or myrobalans with wine. If these have little effect, we may use some of the more powerful ones; but, at the same time, we should be aware, that this practice is hurtful, when the disorder is recent.