“The caustic must not, therefore, be applied in these cases, until the inflammation has entirely subsided; but when there remains only a small superficial ulceration, the caustic may be passed lightly over the ulcerated surface to form an eschar which is to be defended by the gold-beater's skin; for the affection is then reduced to the state of a common superficial ulcer.”
--An Essay on the Application of the Lunar Caustic in the Cure of Certain Wounds and Ulcers
Very thin sheets of steer's intestine. Originally used as the interweaving material for beating gold into fine sheets. Due to the material's strength and endurance, it was an ideal material for this process.