Emplastrum Opii. Lond. Edin. Plaster of Opium

"Take of hard opium, powdered, half an ounce; resin of the spruce-fir, powdered, three ounces; lead plaster, a pound; water, eight fluid ounces. Add the resin of the spruce-fir, the opium, and the water, to the melted plaster, and with a slow fire boil down, until all unite into a proper consistence."

Syn. Opiumspflaster (G.),

This plaster is anodyne, and supposed to be useful in relieving rheumatism and local pains: but although it is undoubtedly certain that opium, in that state in which it exists in the tincture, or when it is dissolved in oil, produces an anodyne effect on the system when externally applied, yet we doubt whether the anodyne properties of this plaster are such as to sanction its employment.

Emplastrum Oxidi Ferri Rubri. Edin. Plaster of Red Oxide of Iron

"Take of plaster of semivitreous oxide of lead, twenty-four parts; white resin, six parts; yellow wax, olive oil, of each three parts; red oxide of iron, eight parts. Rub the red oxide of iron with the oil, and adding the other ingredients melted, mix the whole well together."

Emplastrum Thuris, Dub. Plaster of Frankincense.

"Take of litharge plaster, two pounds', frankincense, half a pound; red oxide of iron, three ounces. To the plaster and frankincense, melted together, add the oxide, stirring them together so as to form a plaster."

These plasters are supposed to be tonic, and are used in muscular relaxations, and weakness of the joints after sprains; but they act by affording mechanical support to the parts.

Emplastrum Picis. 1 Lond. Compound Pitch Plaster

"Take of Burgundy pitch, two pounds; resin of the spruce-fir, a pound; resin, wax, of each four ounces; expressed oil of nutmeg, an ounce; olive oil, water, of each two fluid ounces. Add first the resin of the spruce-fir, then the oil of nutmeg, the olive oil, and the water, to the pitch, resin, and wax, melted together. Lastly, mix the whole, and boil down to a proper consistence."

This plaster is stimulant and rubefacient. It is used in pulmonary affections, applied to the thorax; and in headache and chronic ophthalmia, applied to the temples. When a serous exudation takes place, the plaster should be frequently renewed.

1 Emplastrum Picis compositum, P. L. 1824.

Emplastrum Plumbi. Lond. Lead Plaster

"Take of oxide of lead, rubbed to a very fine powder, six. pounds; olive oil, a gallon; water, two pints. Boil them together over a slow fire, stirring constantly until the oil and oxide of lead cohere into the consistence of a plaster. It will be necessary, however, to add a little boiling water, if that which was employed in the beginning shall be consumed before the end of the process."

Emplastrum Oxidi Plumbi Semi-vitrei, Edin. Plaster of Semivitreous Oxide of Lead.

"Take of the semivitreous oxide of lead, one part; olive oil, two parts; water, a sufficient quantity. Boil them, stirring constantly, until the oil and the oxide unite into a plaster."

Emplastrum Lithargyri, Dub. Litharge Plaster.

"Take of litharge in fine powder, Jive pounds; olive oil, nine pounds; boiling water, two pints. Mix them at a high temperature, constantly stirring until the oil and the litharge unite so as to form a plaster; supplying occasionally any waste of water that may take place."

Syn. Emplatre de diachylon (F.), Bleipflaster (G.).

The use of the water in the formation of these plasters is to moderate the heat of the mixture, until the oil and the oxide combine, by which means the reduction of the metal is prevented; a circumstance which is apt to take place from the strong attraction of the oil for oxygen at a high temperature. By continuing the boiling, the water is dissipated; and the temperature can then be increased to a sufficient degree to give the plaster the necessary consistence. The water should be previously made hot; as cold water is apt to produce an explosion. When long kept, these plasters change their colour, and lose most of their sensible properties. They are intended chiefly to defend excoriated surfaces from the action of the air; and to form the basis of some other plasters.

Officinal preparations. - Emplastrum Hydrargyri, L. E. Em-plastrum Opii, L. Emplastrum Assafoetidae, E. Emplastrum gum-mosum, E. Emplastrum Galbani, L. D. Emplastrum Oxidi Ferri rubric E. Emplastrum Resinae, L. E. D. Emplastrum Saponis, L. E. D. Emplastrum Thuris, D.