266 Pbartnaceutical Preparations. Part III.
OLEUM AMYGDALINUM.
Oil of almonds
OLEUM SEMINUM LINI.
Oil of Unfed.
OLEUM SEMINUM STNAPI.
Oil of muflard feed.
The oil of almonds is preparedfrom the fweet and bitter almondsindifferently ; the oils obtainedfrom both forts being altogetherthe fame. Nor are the differencesof the other oils very coufiderable,the difcriminating qualities of thefubjcdls not refiding in the oilsthat are thus obtained by evpref-fion : the oil of muftard-feed is asfoft, infipid, and void of pungen-cy, as that of fweet almonds, thepungency of the muttard remain-ing entire in the cake left after theexpreffion. The feverai oils differin fome of their properties fromone another; but in medicinalqualities they appear to be allnearly alike, and agree in onecommon emollient virtue. Theyfoften and relax the folids, andob-tund acrimonious humours : andthus become ferviceable, inter-nally, in pains, inflammations,heat of urine, hoarfenefs, ticklingcoughs, &c. in glyfters, for lubri-cating the inteftines, and promot-ing the ejection of indurated fe-ces ; and in external applications,for tenlion and rigidity of particu-lar parts. Their common dofe ishalf an ounce : in fome cafes,they are given to the quantity ofthree or four ounces. The moftcommodious forms for their exhi-bition, we fhalI fee hereafter, inthe chapter of Emulfions.
The oils expreffed from aro-matic fubftances, differ from theforegoing, in retaining for the
moll part, an admixture of the a-romatic matter of the fubjedt. Thusnutmegs and mace yield, upon ex-preffion, an oil impregnated withthe flavour of the fpkes; and anoil expreffed from anifeeds, has agreat ihare of the peculiar fmell ofthe feeds. A purgative oil alio isextradled in America from thepurgative feeds of the ricinus. Itdoes not appear that other quali-ties of vegetables are communi-cated to their expreffed oils.
The rinds of the feverai varie-ties of oranges, lemons and citrons,yield by a kind of expreffion theireffential oils alsnoft pure, andnearly funilar to thofe which areobtained from them by diftiilation.The effential oils, in which thefragrance and aromatic warmth ofthefe fruits refide, are contained innumerous little veficles, which maybe diftinguifhed by the naked eye,fpread all over the furface of thepeel. If the rind is cut in flices,and the flices feparately doubledor bent in different parts, andfqueezed between the fingers, theveficles burll at the bending, anddifcharge the oil in a number offine flender jets. A glafs platebeing fet upright in a glafs or por-celane veffel, and the flices fqueez-ed againft the plate, the little jetsunite into drops upon the plate,and trickle down into the veffel be-neath. But though this procefsaffords the true native oil, in thefame ftate wherein it exifted in thefu'ojecl, unaltered by fire or otheragents, it is not practicable to ad-vantage, uniefs where the fruit isvery plentiful ; as only a fmallpart of the oil it contains can thusbe extradled or colledled.
The oil is more perfe&ly fepa-rated by rubbing the rind upon alump of fugar. The fugar, by theinequality of its furface, produces
the