In succession to these, we shall now have to speak of various other kinds of earth2279 which are made use of in medicine.

Of Samian earth there are two varieties; one known as “collyrium,”2280 the other by the name of “aster.”2281 To be in perfection, the first kind should be fresh, remarkably smooth, and glutinous to the tongue; the second being of a more solid consistency, and white. They are both prepared for use by being calcined and then rinsed in water, some persons giving the preference to the first. They are both of them useful for discharges of blood from the mouth, and are employed as an ingredient in plasters of a desiccative nature. They are used also in the preparation of ophthalmic compositions.