These are unctuous substances, of nearly the same nature as cerates, but having a consistence much less firm, scarcely exceeding that of butter.

Unguentum Antimonii Potassio-Tar-Tratis. Lond. Ointment of Potassio-Tartrate of Antimony

" Take of potassio-tartrate of antimony, rubbed to powder, an ounce; lard, four ounces. Mix."

This ointment is an excellent counter-irritant, bringing out a crop of pustules when it is rubbed on the skin. The part should be rubbed so as to be reddened before the ointment is applied.

Unguentum Acidi Nitrosi. Edin. Ointment of Nitrous Acid

"Take of hog's lard, one pound; nitrous acid, six drachms. Mix the acid gradually with the melted lard, and beat the mixture assiduously as it cools."

Unguentum Acidi Nitrici, Dub. Nitric Acid Ointment.

"Take of olive oil, a pound; prepared hog's lard, four ounces; nitrous acid, an ounce by weight. Melt the oil in a glass vessel, and add the acid to it; let them be exposed to a medium heat in a water bath for a quarter of an hour; then remove them from the bath, and stir them constantly with a glass rod until they become firm."

1 Veratria, like the other newly discovered vegetable alkalies, is a compound substance; and, according to the analysis of Dumas and Pelletier, consists of carbon 66.75, nitrogen 5.04, hydrogen 8.54, and oxygen 19.6, in 100 parts.

In this process the acid is partially decomposed, nitrous gas is evolved, and the ointment is oxidized, assuming a yellow colour and a firm consistence. It was invented by Alyon, who found it useful in syphilitic and herpetic ulcers; and it has been occasionally used in this country for the same purposes; but it is less useful than the ointment of nitrate of mercury.

Unguentum Acidi Sulphurici. Dub. Ointment of Sulphuric Acid

"Take of sulphuric acid, a drachm; prepared hog's lard, an ounce. Mix."

Sulphurous acid is given off during the preparation of this ointment, and the lard is charred. It is black and foetid. It has been used in scabies: but is almost obsolete.

Unguentum Cantharidis. Lond. Blistering Ointment

"Take of blistering flies, finely powdered, an ounce; distilled water, four fluid ounces; resin cerate, four ounces. Boil the water with the blistering flies to half its quantity, and strain. Mix the cerate into the strained liquor, and evaporate it to a proper consistence."

Syn. Kantharidensalbe (G.).

Unguentum Infusi Cantharidis Vesi-Catoriae. Edin. Ointment of Infusion of Blistering Flies

"Take of blistering flies, resin, yellow wax, of each one part; Venice turpentine, hog's lard, of each two parts; boiling water, four parts. Macerate the flies in the water for a night, and strain the liquor, expressing it strongly; add the liquor ,to the fat, and boil until the water be evaporated; then add the wax and the resin, and when these are melted, remove the mixture from the fire; add the Venice turpentine, and mix."

These ointments are sufficiently mild, but they do not always succeed in keeping open a blistered surface. Little efficacy can be ascribed to the blistering flies, much of the acrimony of which is destroyed by the heat employed for the evaporation of the water.2

1 Unguentum cantharidis, P. L. 1787.

2 Galen employed an ointment made by macerating the entire insect in melted lard for twenty-four hours, and then straining by expression. Boerhaave proposed to boil the flies in water, then to pour off the liquid, and make an ointment of the boiled insects with the addition of lard.