Book 5
17
Now emollients and plasters and pastils which the Greeks call trochiscoi, whilst they have much in common, differ in this, that emollients are made chiefly from essences of flowers and even from their shoots, plasters and pastils rather from certain metallic materials: again, the emollients if crushed become quite soft enough; for they are applied over intact skin; the materials out of which plasters and pastils are made are rubbed together laboriously in order that they may not irritate wounds when they are applied to them. But between a plaster and a pastil there is this difference: a plaster must contain some liquefied ingredient, in a pastil only dry materials are used, combined together by a little fluid. Then a plaster is made in this way: dry medicaments are rubbed down separately, then when they have been mixed, either vinegar is dropped in or any other liquid free from fat that is at hand, and these ingredients are rubbed together again. The materials capable of being liquefied are melted all together over the fire, and if there is to be any admixing of oil, it is then poured in. A dry ingredient is even sometimes boiled in oil beforehand: when what should be done separately has been accomplished, all are mixed together. But the making of pastils, on the other hand, is this: dry medicaments which have been rubbed together are mixed by the aid of a liquid free from fat, such as wine or vinegar and the mixture is dried again, and when required for use, dissolved in a liquid of the same kind. Further, a plaster is laid on, a pastil is smeared on, or is mixed with something softer such as a cerate.
