* * * * * COMMENTARY. It is now well ascertained that _burnt shells_ consist principally of lime. They, may, therefore, be supposed to form a good stimulant application to certain cutaneous diseases and tumours of an indolent nature, as recommended by our author and Dioscorides. (v, 177.) Oribasius says, that they are very efficacious in repressing fungous flesh when sprinkled in the form of a fine powder. Ὂστρεα, Ostrea, _Oysters_; the burnt shell is possessed of similar powers to the buccina, but is not of so gross a consistence. It is used, therefore, as a detergent to the face, and whitens the teeth. When washed it is freed from pungency, and is useful for incarnating and cicatrizing ulcers attended with a copious discharge. * * * * * COMMENTARY. Galen gives the same account of the burnt shells of oysters or snails. He says, that if a shell be washed and burnt it imparts an empyreuma to the water, which renders it heating and attenuant; whereas, what remains is devoid of pungency and terrene, and it is useful for the filling up and cicatrization of ulcers. He recommends the ashes of all burnt shells as a dentifrice, in which case they do not require to be finely levigated as they should be when applied to sores. (De Simpl. 11.) This article is not treated of by Dioscorides, the reason of which probably is, that in his time the word ὄστρεα was a term applied to the whole class of the ὀστρακόδερμα. See Commentary (i, 91.) They are treated of in the same terms by the Arabians as by the Greeks. See Avicenna (ii, 2, 529); Rhases (Cont. l. ult. i, 224); Serapion (c. 443.) Ὀῦρον, Urina, _Urine_; all kinds of it are hot and acrid, but that of man is weaker than the urine of other animals, with the exception of castrated boars, but it is considerably detergent; and it is said that some who have drunk it in the plague have recovered. It also cures leprosy, putrid ulcers, achores, and furfures; and likewise sprains of the feet when not inflamed. That of boys not come to puberty is stronger, and from it the chrysocolla is formed. The urine of mules suits with arthritic remedies. That of goats and of camels is laxative of the belly, and hence is given in dropsical complaints. * * * * *