PHARMACY. 



pulse and relieving 1 the head. The chief 

 advantage they have depends on the sud- 

 denness of their action. 



CLASS. XXV. Linimenta. 

 CLASS XXVI. Unguenta. OIXTMEXT. 

 CLASS XXVII. Cerata. CERATES. 

 CLASS XXVIII. Emplastra. PLASTERS. 



We connect these tog-ether, as being all 

 oleaginous or fatty combinations for ex- 

 ternal application, and as merely differ- 

 ing from each other in their degree of 

 consistency. Deyeux has, indeed, lately 

 defined plasters to be combinations of oil 

 with metallic oxides ; but as this would 

 comprehend many of our present oint- 

 ments, and exclude many of our plasters, 

 we shall adhere to the old meaning of the 

 terms. 



Liniments are the thinnest of these 

 compositions, being only a little thicker 

 than oil. 



Ointments have generally a degree of 

 consistence like that of butter. 



Cerates are firmer, and contain a larger 

 proportion of wax. 



Plasters are the most solid, and when 

 cold should be firm, and not adhere to the 

 fingers ; but when gently heated should 

 become sufficiently soft to spread easily, 

 and should then adhere to the skin. Plas- 

 ters derive their firmness either from a 

 large proportion of wax, resin, &c. or 

 from the presence of some metallic ox- 

 ide, such as that of lead. 



Plasters should have such a consistence, 

 that although when cold they do not ad- 

 here to the fingers, they become soft and 

 plastic when gently heated. The heat of 

 the body should render it tenacious 

 enough to adhere to the skin, and to the 

 substance on which it is spread. When 

 prepared, it is usually formed into rolls, 

 and inclosed in paper. Plasters of a small 

 size are often spread on leather, some- 

 times on strong paper, by means of a spa- 

 tula gently heated, or the thumb. The 

 leather is cut of the shape wanted, but 

 somewhat larger; and the margin all 

 round, about a quarter of an inch in 

 breadth, is left uncovered, for its more 

 easy removal when necessary. Linen is 

 also often used, especially for the less ac- 

 tive plasters, which are used as dressings, 

 and often renewed. It is generally cut 

 into long slips of various breadths, from 

 one to six inches. These may either be 

 dipped into the melted plaster, and pass- 

 ed through two pieces of straight and 

 smooth wood, held firmly together, so as 



to remove any excess of plaster ; or, what 

 is more elegant, they are spread on one 

 side only, by stretching the linen, and ap- 

 plying the plaster, which has been melt- 

 ed and allowed to become almost cold, 

 evenly by means of a spatula, gently heat- 

 ed, or, more accurately, by passing the 

 linen on which the plaster has been laid, 

 through a machine formed of a spatula 

 fixed, by screws, at a proper distance 

 from a plate of polished steel. 



To prevent repetition, the Edinburgh 

 College give the following canon for the 

 preparation of these substances : 



" In making these compositions, the 

 fatty and resinous substances are to be 

 melted with a gentle heat, and then con- 

 stantly stirred ; adding, at the same time, 

 the dry ingredients, if there be any, un- 

 til the mixture, on cooling, becomes 

 stiff." 



Linimentum simplex, Edin. simple lini' 

 ment, wax and oil. 



Oleum ammoniatum, Edin. linimentum 

 ammoniac, Lond. oil or liniment of ammo- 

 nia, volatile liniment. 



Linimentum ammoniac fortius, Lond. 

 volatile liniment, stronger. 



Oleum lini cum calce, Edin. linseed oil 

 with lime. 



Oleum camphorat. Ed. camphorated 

 oil. 



Unguentum adipis suillae, Lond. oint- 

 ment of hogs' lard. 



Unguentum simplex, Edin. ointment of 

 simple wax and oil. 



Unguentum spermatis ceti, Lond. Dubl. 

 ointment of spermaceti. 



Unguentum cerze, Lond. Dubl. ointment 

 of wax. 



Unguentum acidi nitrosi, Edin. ointment 

 of nitrous acid. 



Unguentum resinas flavs, Lond. Dubl. 

 ointment of yellow resin. 



Unguentum elemi, Dubl. unguentum 

 elemi compositum, Lond. ointment of 

 elemi. 



Unguentum picis, Lond. Dubl. ointment 

 of tar. 



Unguentum sambuci, Lond. Dubl. oint- 

 ment of elder. 



Unguentum cantharidis, Lond. Dubl. 

 ointment of cantharides. 



Unguentum infusi meloes vesicatorii, 

 Edin. ointment of mild epispastic. 



Unguentum pulveris meloes vesicatorii* 

 Edin. ointment of stronger epispastic. 



Unguentum hellebori albi, Lond. Dubl 

 ointment of white hellebore. 



Unguentum sulphuris,Lond. Dubl. oint- 

 ment of sulphur. 



