Page:Willich, A. F. M. - The Domestic Encyclopædia (Vol. 3, 1802).djvu/306

^S4] OIL wnshecl with sonp-sud^j In order to f radirats mos.^. III. Vegetable Oils are pro- cured either bv expression, infu- sion, or disttllation, 1. Those by expr-ession are ob- tained from the seed, leaves, fruit, and bark of plants; which, being poanded in a mortar, the oil is forced out by means of a press, without the aid of beat. Such are the oils of olives, almonds, beech- mast, rape, and linseed. 2. In esseritial oils procured by infusion or decoction, the virtues {>f some particular plant are ex- iradted. To this kind belong the oil^ of roses, chamorailc, &c. ; wliich, however, ought to be boil- ed o;ily so long as there remains anv a<:fueous moisture ; for other- "wise they will become blnck. 3. Other essential oils of vegeta- bles are prepared by distillation, onlv from those plants, or parts of phints, that poisess a considerable odour. They contain the fragrance, ■warmth, pungency, and often the .acli'C powers of t'.e substance, irom which they are drawn ; whence they have received the n2me cf essences, or essential oi/s ; for instance, those of cloves, cin- namon, &:c. — See Essence. As many of these oils are ex- pensive, and frequently adulte- rated with alkohol, or with ex- pressed and inferior essential oils, we shall point out a few methods by which such practices may be detef^ed. I. It there be reason to su^peft that an essence is sophisticated ■wilh alh;b.ijL, or reftified spirit of ■wine, it will be advisable to pour a few drops int» a gla?s of pure ^ater ; and, if it be actually a base mixture, the whole wi.l now be- €OK»e milky ; aud, oix repeatedly O I N agitating th^ glass, all the spirltuw ous part will be absorbed by the water, while the genuine oil will float on the surface. 2. If the adulteration be eflfecled . by the aid of an expressed o:l, the fraud may he discovered, bysimply adding a little spirit of wine to a fewdrops of tiie suspected oil, and- shaking them together : for the spirit will dissolve all tiie essence, or that obtained by distillation, ■ v.hile the expressed oil will not be in the least affefted, 3. Lastly, if an essential oil should have been mixed with a cheaper or inferior essence (which is usually effected by distilling oil of turpentine with the herbs from which the essential oil' is drawn), the imposition will speedily and spontaneously appear. But there is a more expeditious mode of de- tecting it ; namely, by dipping a piece of rag, or paper, into the suspected essence, and holding it before the lire ; when the grateful fragrance of the plant will be vola^ tilized, and the scent of the tur- pentine wiil remain. On the properties or %'irtues of essential oils, we cannot enter in tills place ; for, as they correspond with those of the substances from which they are obtained, the reader will, in particular instances, resort to t'.^eir alphabetical series — .See also Menstruum, OINTjMENT, a preparation consisting of certain unduous mat- ters, whether animal or vegetable, tor the cure of sores, burns, ulcers, and tumors. Ointments ditler from plasters only in their consistence : those prepared of animal tat appear to be more ciUgenial to the human sys- tem, than such as are compound- ed witix vegetable oils j though, the fornaej^