This is made by incorporating soap with the lead plaster. It is a very mild preparation, sedative, and supposed to be discutient, and hence employed in chronic swellings and indurations, spread usually upon leather.

A few other preparations of lead are noticed by authors; but they are little employed, and probably capable of producing no effect, which could not be as well or better obtained from some one of those already referred to. Among them may be mentioned the chloride, saccharate, and tan-nate of lead, of which an account may be seen in Pereira's Materia Medica; and of the last in the twelfth edition of the U. S. Dispensatory. Tannate of lead may be made with great facility by adding a solution of acetate of lead to infusion of galls or oak bark. It is used exclusively as a local application, and for this purpose may be incorporated with glycerin. It may be used in excoriations, as a resolvent in strumous swellings, and, in the form of ointment, as a dressing for bed-sores, and gangrenous ulcers.

Besides Alum and the Preparations of Lead, there are several other mineral substances which are decidedly astringent; but all of them have other properties, more important, and for which they are more employed; and it is deemed best, in order to give due prominence to these properties, and at the same time to avoid repetition, to classify them with those medicines with which they agree in their greatest efficiency, and to treat of their astringent qualities incidentally. Such are especially the sulphates of iron, zinc, and copper, and, in a less degree, other preparations of the same metals, nitrate of silver, corrosive chloride of mercury, sulphuric acid, and lime. (See Tonics, Alteratives, and Antacids).