Preparation. - By heating oxide of lead with olive oil and water. The oleic acid of the oil combines with the lead, forming oleate of lead, and leaving glycerine. This plaster is a lead soap.

Preparations.

b.p.

Emplastrum Ferri.

„ Galbani.

Hydrargyri. „ Resinae.

„ Saponis.

U.S.P

Emplastrum Ammoniaci cum Hydrargyro. ,, Asafoetidae.

,, Ferri.

„ Galbani.

„ Hydrargyri.

Opii. „ Resinae.

,, Saponis.

Unguentum Diachylon (1 in 4, nearly). And several other plasters into which it enters, as resin plaster.

Uses. - Lead plaster is used to hold together the edges of wounds, to protect irritable surfaces, either alone or by keeping other dressings in contact with them by means of its adhesive power. It is also used as a means of applying pressure.

Unguentum Diachylon (U.S.P.) is very useful in chronic eczema, and in the acute form after severe inflammatory symptoms have subsided. It must be applied thickly spread on a cloth, which is kept in place by a bandage. It is also useful in hyperidrosis, especially of the feet, the treatment being continued, without washing, and with a daily change of dressing, for ten to fourteen days. In sycosis, after shaving, the application of soft soap twice a day, and diachylon ointment in the intervals, has a very beneficial effect.