wards wrote two heroic poems, entitled, the he carried over to Georgia in 1738. In 1740, he Ephefian Matron, and the Roman Slaves He attacked the Spaniards, took two forts, and benext compofed the Charolics, an epic poem, in fieged St Auguftine, but without fuccess. In 1742, 12 books, in honour of king Charles I, but this the Spaniards attacked the new settlement, but was loft in the fire of London; when his houfe in were repulfed. In 1745, he accompanied the D. White Friars was burnt down, and his whole for of Cumberland into Scotland, which was his laft tune, except about 51. deftroyed. He, however, military expedition. In 1754, he married Eliz. got his houfe rebuilt, fet up a printing office, was Wright, an heirefs, and spent the rest of his life appointed cofmographer and geographic printer, in eafy retirement at her feat of Cranham Hall in and printed several great works, tra: slated or col. Effex; where he died, June 30, 1785. lected by himself and his affiftants, particularly his Atlas. He died in 1676 OGIVE. n. f. in architecture, an arch or branch of a Gothic vault; which, inftead of being circu lar, paffes diagonally from one angle to another and forms a crofs with the other arches. The middle, where the ogives crofs each other, is called the key; being cut in form of a rofe, or a cul de lampe. The members or mouldings of the ogives are called nerves, branches, or reins; and the arches which feparate the ogives, double arches. *To OGLE. v. n. [oogh, an eye, Dutch.] To view with fide glances, as in fondnefs; or with a defign to be heeded. From their high scaffold with a trumpet check, And ogling all their audience, then they fpeak. Dryden. -Could they talk of the different afpects and conjunctions of planets, they need not be at the pains to comment upon oglings and clandestine marriages. Addifon-Whom is he ogling yonder? himfelf in his looking-glafs. Arbuthnot. *OGLER. n. f. [oogheler, Dutch.] A fly gazer; one who views with fide glances.-Upon the dif ufe of the neck piece, the tribe of oglers ftared the fair fex in the neck rather than in the face. Addif. -Jack was a prodigious ogler; he would ogle you, the outside of his eye inward, and the white upward. Arbuthnot. (1.) OGLETHORPE, James Edward, a British officer, of a very ancient family in Yorkshire, born about 1698. He entered early into the army, and was made a captain lieutenant in the Queen's Gre nadiers, in 1715. He obtained the rank of colonel, Aug. 25, 1737; of major-general, March 30, 1745 eutenant-general, Sept. 13, 1747; and of general, Feb. 22, 1765. He was elected M. P. for Hallemere in Surrey, in 1722, and continued to repreleet that borough til 1754. In 1729, finding a gentleman, whom he went to vifit in the Pet piifon, loaded with irons and otherwife barby v ufed, he engaged in the philanthropic in upto the state of the jails, and was appoint ed chairman of the Committee of Inquiry by the Houle of Commons, upon whofe inveftigations fuch facts came out as were difgraceful to huma Fury. In 1732, he was appointed governor of Gorgia, in the fettlement of which he engaged with that ardour which marked all his undertakings; and after overcoming numberlefs difficulties, proved fuccefsful, though at the expence of large fums of his private fortune, which, it is faid, were never.epaid. In 1734, he returned to EngAnd, and was chofen deputy governor of the trieen company; and in 1735, carried back with im to Georgia Meffrs John and Charles Wesley, a the picus in en ior of instructing the Indians. Returning to England, he railed a regiment, which (2.) OGLETHORPE, a county of Georgia, on the N. bank of the Alatamaha, W. of Liberty county. It is defended by Fort Telfair on the SE. OGLIASTRO, a town of Sicily, in the valley of Mazara; 9 miles SSE. of Palermo. (1.) OGLIO, a river of Italy, which rifes at the foot of the mountains of Trent, foon after falls into the lake Ifeo, then rifing from the lake, re. fumes its course above Caprelo weft-ward, paffes by Breno, Palazzuolo, Orzi, Nuova, Ustiano, Caneto, &c. and joins the Po, at Borgoforte. (2.) OGLIO, a town of Italy, in the dep. of the Lario, district and late county of Como, feated on the E. bank of Lake Como. (3.)* OGLIO. n. f. [from olla, Spanish.] A difh made by mingling different kinds of meat ; a medley: a hotchpotch.-Like great oglios, they rather make a fhew than provoke appetite. SucklingWhere is there fuch an oglio in medley of various opinions in the world again, as those men entertain in their fervice? King Charles.-He that keeps an open house should confider that there are oglios of guefts, as well as of dishes. L'Eftrange. ÖGLOSA, an island of Italy, in the Tyrrhene fea, E. of Corfica, now called Monte Chrifto. Plin. iii, 6. OGMORE, a river of S. Wales, which rises on the borders of Brecknockshire, and runs into the Severn, 4 m. SW. of Bridgend, in Glamorganshire. OGNATA, a town of Spain, in Guipufcoa. OGNY, a town of France, in the dep. of the Mofelle; 5 miles NE. of Gorze, and 3 S. of Metz. OGOLETZ, an island of Russia, in the Straits of Vaigatskoi. Lon. 69 23. E. Ferro. Lat. 69. 40. N. OGOR, a river of Ruffia, which runs into the Duna, 12 miles SE. of Riga. OGOST, a river of European Turkey, which runs into the Danube, near Rakova, in Bulgaria. OGOUA, a town of Africa, on the Slave Coast, containing about 250 well built houses, with a fquare in the centre, furrounded with fhops, where all kinds of wares and provifions are fold. The people are fociable, and governed by magiftrates. OGRAM, LOUGH, a lake of Ireland, in Clare county, 8 miles NW. of Killaloe. OGRAN, a town of Hungary, 15 miles NNW. of Prefburg. * OGRESSES. n. f. [in heraldry.] Cannon balls of a back colour. Ainf-worth. OGYGES, king of Thebes, or as others say, of Ogygia and Actæ, afterwards called Baotia and Attica. He is recorded to have been the firft founder of Thebes and Eleufin. The famous deluge happened in his time, in which fome fay he perished with all his subjects, A. A. C. 1796. (1.) OGYGIA, the island of Calypfo; (Homer.) placed by Pliny in the Sinus Scylaceus, in the lonian Sea, oppofite to the promontory Lacinium; by by Mela who calls it Eac, in the strait of Sicily: OHRA, a river of Lower Saxony, which runs others place it at the promontory Circeium, and into the Unftrut, 6 miles N. of Erfurt. call it the island of CIRCA. Dryden. OHAMENO, a harbour of Ulietea. OHERURNA, a harbour of Otaha. OHETEROA, one of the South Sea islands lately discovered. It is neither fertile nor populous; nor has it an harbour or anchorage fit for fhipping, and the difpofition of the people is hoftile to fuch as vifit them. Lon. 150. 47. W. Lat. 22. 27. S. OHEVAHOA, an island in the South Sea. (1.)OHIO, a beautiful river of the United States, formed by the junction of the Allegany and the MONONGAHELA, between the Allegany moun. tains and the lake Erie; and running SW. through a moft delighful country, and receiving many fmaller rivers in its 'paffage, at length falls into the Miffifippi, in about Lat. 37° Ñ. Its total length is 1188 miles: its general breadth 600 yards, 900 at its mouth, and nowhere above 1200. It feparates the North-Western Territory from Kentucky on the S. and Virginia on the SE. It is a mile broad at the Rapids, which are a grand calcade, occafioned by a ledge of rocks that ftretch across the bed of the river, near Louisiana, in Lat. 30. 8. N. (2) OHIO, a county of Virginia, bounded on the NW. by the Ohio, and E. by Washington county in Pennfylvania. It contained 4,931 citizens and 212 flaves in 1795. The chief town is LIBERTY. OHIOPE, a river of Georgia, which runs into the Alatamaha, in Oglethorpe county. OHIOPIOMINGO, a town of Kentucky, in Nelfon county, on the Ohio; 60 miles WSW. of Franckfort. OHIOPYLE FALLS, a cataract of the Youg hiogany, in Pennsylvania. See YouGHIOGANY. OHITAHOO, an island in the S. Pacific Ocean. Lon, 139. 6. W. Lat. 9. 54. S. OHLA, a river of Silefia, which rifes 4 m. S. of Munfterberg, and runs into the Oder at Breslau. OHLAU, a town of Silefia, in Brieg, on the Ohla, in a marfh furrounded with walls and ramparts. In 1502 and 1641, one half of it was burnt. In 1741, it was taken by the Pruffians. It is 8 miles NW. of Brieg, and 14 SE. of Breslau. OHLENHAUSEN, a town of Auftria. OHLM, a town of France, in the dep. of the Rhine and Mofelle, and late electorate of Mentz on the Selz; 6 miles SW. of Mentz. OHM, a river of Germany, which runs into the Lahn, near Marpurg, in Hesse. OHRDRUF, a town of Saxe Gotha, capital of Gleichen county. It has been several times burnt. It has numerous mangfactures. It is 8 miles SSE. of Gotha, and 15 SW. of Erfurt. OHRENHAU, a town of Franconia, in Aichftadt, 6 miles SSE. of Anfpach. OHRLE, a town of Saxony, in Bremen. OHRN, a river of Germany, in Franconia. Oi, a river of Ruffia, running into the Enifei. OIA, a river of Ruffia, which runs into the Gulf of Obskaia; in Lon. 90, 10. E. Ferro. Lat. 68. o. N. OJA, two towns of Sweden; 1. in Smaland, 9 miles SW. of Wexio: 2. Schonen, 21 miles SE. of Lund. OIBO, an island in the E. Sea, on the coast of Africa Lon. 39. 50. E. Lat. 11. 52. N. (1) OICH, a river of Scotland, in Invernessfhire, which rifes from the E. extremity of LochOich, and after running 5 miles, fails into LochNefs. (2.) OICH, LOCH. See LOCH-OICH. OICHILL, a mountain of Perthshire, 12 miles SW. of Perth. OJECK, a town of Poland, in Sandomirz. OJEN, a town of Spain, in Grenada. OJEREN, a lake of Norway, in Agerhuus; 64 miles long and 2 broad; 10 miles E. of Chriftiania. OJESTADT, a town of Norway, 24 miles NNE of Chriftianfand. OIGNON, a river of France, which runs into the Saone, 9 miles S. of Gray. (1.) * OIL. n. J. [oal, Saxon; oleum, Lat.] 1. The juice of olives expreffed.-Bring pure oil olive beaten for the light. Ex. xxvii. 20. 2. Any fat, greafy, unctuous, thin matter.-In most birds there is only one gland; in which are divers cells, ending in two or three larger cells, lying under the nipple of the oil bag. Derham. 3. The juices of vegetables, whether expreffed or drawn by the ftill, that will not mix with water.-Oil, with che, mifts called fulphur, is the second of their hypoftatical, and of the true five chemical principles, It is an inflammable, unctuous, fubtile fubitance, which usually rises after the fpirit. The chemifts attribute to this principle all diverfity of colours. There are two forts of oil; one which will swim upon water, as oil of anifeed and lavender, which the chemifts call effential; and another kind, which probably is mixed with falts, and will fink in water, as the oil of guaiacum and cloves. Harris.After this expreffed oil, we made trial of a distilled one; and for that purpose made choice of the common oil or fpirit. Boyle. A curious artift long inur'd to toils Of gentler fort, with combs, and fragrant oils. (7.) OIL, METHOD OF PURIFYING RANCID. and for domeftic ufe, a very small chamber will Mr Collier has obtained a patent" for a chemical be fufficient. When water is to be sweetened, or procefs for freeing fish-oils from their impurities freed from any' putrid or noxious particles it may, in point of fmell, tafte, and colour; and impro- from whatever caufe, contain, it paffes, in its ved ftrainers for oils and other liquids; with other way to the filtering chamber, through an iron box inftruments for afcertaining their qualities, and af- or cylinder L M N O, in Fig. 1, containing char. fifting their burning. The machines are illustra, coal, finely powdered, or any other antifeptic ted by the figures on Plate 247. The chemical fubftance infoluble in water; which fubftance is procefs is thus performed: "I put a quantity (fays forced clofely into the box by any mechanical Mr Collier,) of any fpecies of fifh-oil, or mix- power; after which the water is made to país ture of different forts of fish-oil, into any conve- through it by the hydroftatic preffure, through a nient veffel, which I heat to the temperature of tube of any fufficient height. This box has 2 aper110 or 120 of Fahrenheit's scale; I then add, of tures, to receive and deliver the fluid, and these are cauftic mineral alkali (of the specific gravity com- opened or closed by cocks or fcrews, at P and Q, monly described as 1°25, or of such strength that a or any other method used for such purposes; and, phial containing 1000 grains of diftilled water will being affixed to the machine by other screws, or contain 1250 grains of thefe leys) a quantity fcrews and collars, may be eafily detached from equal to 4 parts to roo, by weight, of the quanti- the fame. Thus, whenever the charcoal begins ty of the oil. I then ftir or agitate the mixture, to lofe its antifeptic properties, the box is remoand leave it to ftand a fufficient time for the falts ved, and heated till it is red hot, by which means and fediment to fubfide. It is then drawn off in the foreign matter efcapes through the fmall aperto another veffel, containing a fufficient quantity tures; after which, the box is left to cool, and of fresh burnt charcoal, finely powdered, or of the charcoal becomes fweet, pure, and equalany other fubftance poffeffing antifeptic properties, ly fit for ufe as at firft, though the procefs be ever in a powdered or divided state, with an addition fo often repeated. Fig. 2. is a machine or conof a small proportion of diluted fulphuric acid, trivance for ftraining oil from the bottoms. I furfufficient only to decompofe the fmall quantity of ther claim the exclufive privileges ariling from the faponaceous matter till fufpended in the oil, invention of filtering machines in the form of which will appear by the oil becoming clear at ftills, in which charcoal may be repeatedly burnthe furface. The contents of this veffe! are alfo ed, after any fluid fubftances have paffed through agitated, and the coal, faline, and aqueous parti. it, either for the purpose of freeing them from cles left to fubfide; after which, the oil is paffed putrid or noxious particles, or of discharging their through proper strainers, after described, and is colouring matter; which filtering stills are so conthereby rendered perfectly tranfparent and fit for trived, that the fluid may pass through in any ufe. The principle of my improved ftrainers or quantity, without difplacing the charcoal, as in filtering machines, by which, as far as refpects Fig. 3. The part of the fluid remaining interfperthem, I deem myfelf entitled to the exclufive pri- fed among the charcoal, may be driven over by a vilege fecured by the patent, confifts in the means proper degree of heat, and be employed for maapplied to combine hydroftatic preffure (which ny inferior purposes of the arts and manufactures. increases as the perpendicular height of the fluid) The heat may be raised so as to purify the charwith the mode of filtering per afcenfum, thereby coal, as in the machines for filtering water, or procuring the new and peculiar advantage, that other fluids for domeftic purposes. The flue of the fluid and its fediment take oppofite directions; the ftills is fo conftructed, that water may be emand alfo, in whatever is new in the conftruction ployed to cool them, without the lofs of time reof my machines herein defcribed. It cannot but quifite for their gradually parting with their heat be seen, that a paffage for the air, more free from to the furrounding atmosphere, fo as to be fit for objection than any hitherto adopted, is here con- a subsequent operation. My inftruments for aftrived in those defigned for domestic purposes, Fig. certaining the comparative qualities of oils, deI.; and alfo, that the eafy means of emptying pend in part on the principal of their specific gratheir fediment facilitates the operation, and ren- vities; fpermaceti oil, contrafted with other fishders their use perfectly fatisfactory to the moft oils, being as 875 to 920. For this purpose, I ufe minute obferver. A great advantage attending a glafs veffel, of any convenient fhape, furnished this invention is, that the dimenfions of the cham- with a bubble, also of glafs, and a thermometer. ber in which the fediment is received may be va- If the oil is pure, this bubble finks, when the merried, while the filtering surface remains the fame. cury rifes to a certain ftandard, by the application To adapt thefe machines, not only to the purposes of the hand, or of any other heat, to the veffel of families, workhoufes, hofpitals, public chari- containing the oil. If the fpermaceti oil is imties, the navy, or the merchant fervice, but alfo pure, the bubble will still float, though it is of to all the purposes of oil-men, of diftillers, of the the temperature required, and the degree of folaboratory, the brewery, &c. chambers of various reign or impure matter will be fhewn, by the capacities must be provided for the fediment and fcale of the thermometer at which the bubble precipitated matter. With refpect to the oil finks. To determine what tendency oils used trade, the space required is very great, especially for burning have to congeal in cold weather, I for fpermaceti or Brazil bottoms. In the various put equal quantities of nitre and Yal ammoniac, proceffes of the laboratory, no limits can be fixed, finely powdered and mixed, into a phial of thin but all dimenfions will be occafionally required. glafs, or any other convenient veffel, containing In diftilleries and breweries they may be fmaller rather more than fufficient water to diffolve them; in proportion; and in thofe defigned for water, or I put any other freezing mixture into fuch vet fel: fel: I then immerfe a thermometer therein, and let a fingle drop of the oil under experiment fall on the outfide of the veffel, where it immediately congeals. As the cold produced by the mixture gradually ceases, it is easy to observe, by the thermometer, at what point of temperature the oil becomes fluid, and runs down the fides of the glafs.-Fig. 1. A is the ciftern into which the water, or other fluid to be filtered, is put. BBB, a tube opening into the bottom of the ciftern A, and bent along the bottom of the machine, conveying the fluid into CC, the filtering chamber, which is covered with leather bound down round its circular rim, and through which leather the water is percolated. DD, the bafon, rifing above the level of the chamber, and receiving the filtered liquor. E, the spout by which it runs off, into a pitcher or other veffel. F, another spout, furnished with a cock, to draw off the foul water from the chamber, when neceffary. GGGG, the air-tube, which begins above the level of the chamber, is covered with a button, which faves the leather from being cut, and has a fmall lateral aperture for the air to be carried off. This pipe paffes along the bottom, and up the fide, and, rifing above the level of the water in the ciftern, is there closed, except a small lateral aperture, through which the air efcapes. H, fig. 4. a guard or rim, with cross bars, put over the leather, to keep it from being forced up by the water. It is faftened down by means of two notches on oppofite fides of the guard, by which it locks into two ftaples rivetted into the bottom of the bason. I, the lid, fliding down to cover the water from duft, and fufpended at pleasure by means of K, K, two fprings on each tube, for that purpose. LMNO, a cylindrical box, containing charcoal, which is connected with the above, by means of the tube P, and a continuation of the tube B., LM, the water tube B continued below the charcoal aparatus, fo that the fluid may pass through the fame into the cylinder at Q, from whence it enters the chamber at P, fo as to be filtered through the leather as before defcribed. R, R, collars, which may be unfcrewed at pleasure, fo as to detach the charcoal apparatus, when the charcoal requires to be purified by heat. S, S, two cocks, to direct the fluid through the charcoal cylinder, or immediately into the filtering chamber. Fig. 2. A, a tube or ciftern, containing the oil to be filtered, and fupplying a tube of fufficient height for the hydroftatic preffure to operate. BB, a main tube, of wood, tin, leather, or cloth, to which any number of bags C, C, C, C, of the fize and fhape of corn-facks, or any convenient fize and fhape, may be connected; these are bound to Atraight double iron bars D, D, D, D, furnished with a hinge at one end, and a fcrew at the other, by opening which the bags may be emptied. EE, a trough underneath, made to receive the filtered oil. Fig. 3. A, a funnel, cafk, or ciftern, into which the fluid is put, which paffes down B, a tube fitted into the fame, through which it enters C, an iron ftill, full of finely powdered and fifted charcoal, through the head of which the fluid paffes into any receiver. D, a fire-place, of any conftruction, to drive over the fluid remaining interfperfed among the charcoal, and alfo to purify the charcoal by an increase of temperature, when required. E, a cock to let water into the flues, to cool the apparatus for a fubfequent operation." (8.) OIL, ROCK. See PETROLEUM. (9.) OILS, ANIMAL, are their fats, which are originally vegetable oils: all animal fubftances yield them, together with their volatile falts, in diftillation. Oils or fats may be obtained, by boiling and expreffion, from certain animal fubftances; for the membranes which contain the fat, being chopped fmall, and fet in a pan over the fire, become fit for the canvas bag, and, by preffure, afford a large quantity of fat; as we fee in the art of chandlery, which, thus extracting the oily matter, leaves a cake behind, commonly called graves. (10.) OILS OF MADAGASCAR. We have this account of different oils in the island of Madagascar in the Univerfal History. The moft common are thofe of menach-tanhetanhe, menach fignifying oil, menachil, menach-chouivau, menachmafoutra, menach-vourave, menach-apocapouc, menach-vintang, and menach arame. Menachtanhetanhe is drawn from a particular plant called, in the language of the country, tanhetanhe, and known in Europe by the name of palma Chrif ti, or Ricinus. Menachil is an oil from the feed of fefame, which they call voancaze; a great quantity whereof is made in the valley of Amboule. Menach-chouivay is drawn from a fruit of the fize of an almond, extremely good in liquors or meats. Menach-mafoutra is drawn from nuts, the fruit of the tree which produces dragon's blood. Menach-vourave is drawn from a fruit named fontfi. Menach-apocapouc is fqueezed from the fruit apocapouc, extremely poisonous. Menach-vintang is an oil from large acorns, or maft. Menach arame is drawn from nuts, the fruit of the tree from which the gum tacamahaca is produced. (11.) OILS, VEGETABLE, are obtained by expreffion, infufion, and diftillation. i. OILS, ESSENTIAL, OF VEGETABLES, are obtained by diftillation with an alembic and a large refrigeratory. Water must be added to the materials, in fufficient quantity to prevent their burning; and they should be macerated or digested in that water, a little time before distillation. The oil comes over with the water; and either fwims on the top, or finks to the bottom, according as it is fpecifically heavier or lighter than water, This procefs is applicable to the diftilling of the effential oils from flowers, leaves, barks, roots, woods, gums, and balfams, with a flight alteration of circumftances, as by longer digeftion, brifker diftillation, &c. according to the tenacity and hardnefs of the fubject, the ponderofity of the oil, &c. Effential oils may be divided into two claffes according to their different fpecific gravities; fome floating upon water, and others readily finking to the bottom. Thus, the effential oils of cloves, cinnamon, and faffafras, readily fink, whereas thofe of lavender, marjoram, mint, &c, fwim in water: the lighteft of thefe effential oils is, perhaps, that of citron-peel, which even floats in fpirit of wine; and the heaviest feems to be oil of faffafras. For obtaining the full quantity of the more ponderous oils from cinnamon, cloves, faf fafras, nuts, beech-maft, &c. afford a copious oil by expreffion; and the leaves of rofemary, mint, rue, wormwood, thyme, fage, &c. the berries of juniper, olives, Indian cloves, nutmeg, mace, &c. the harks of cinnamon. faffafras, and clove, yield a confiderable proportion of effential oil by difpreffion is very fimple; thus if either sweet or bitter almonds, that are fresh, be pounded in a mortar, the oil may be forced out with a prefs, not heated: and in the fame manner fhould the oil be preffed from linfeed and muftard. The avoiding the ufe of heat, in preparing these oils intended for internal medicinal ufe, is of great importance, as heat gives them a very prejudicial rancidnefs. This method holds of all those vegetable matters that contain a copious oil, in a loose manner, or in certain cavities or receptacles; the fides whereof being broken, or squeezed, makes them let go the oil they contain: and thus the zeft or oil of lemon peel, orange peel, citron peel, &c. may be readily obtained by preffure, without the ufe of fire. But how far this method of ob taining oils may be applied to advantage, seems not hitherto confidered. It has been commonly applied to olives, almonds, linfeed, rapefeed, beech-maft, ben-nuts, walnuts, bay-berries, mace, nutmeg, &c. but not, that we know of, to juniper berries, cafhew-nuts, Indian cloves, pineapples, and many other fubftances that might be enumerated, both of foreign and domestic growth. It has, however, been of late fuccessfully applied to mustard-feed, fo as to extract a curious gold coloured oil, leaving a cake behind, fit for mak fafras, &c. it is proper to reduce the fubjects to powder; to digeft this powder for fome days in a warm place, with thrice its quantity of foft river water, made very faline by the addition of fea-falt, or sharp with oil of vitriol; to use the ftrained decoction, or liquor left behind in the ftill, inftead of common water, for fresh digeftillation. The method of procuring oils by extion; to ufe for the fame purpose the water of the fecond running, after being cleared of its oil; not to diftil too large a quantity of thefe fubjects at once; to leave a confiderable part of the ftill, or about one fourth, empty; to use a brifk fire, or a strong boiling heat, at the firft, but to flacken it afterwards; to have a flow ftill-head, with a proper internal ledge and current leading to the nofe of the worm; and, finally, to cohobate the water, or pour back the liquor of the fecond running upon the matter in the ftill, repeating this once or twice. The directions here laid down for obtaining the ponderous oils to advantage, are cafily transferred to the obtaining of the lighter. Many of the effential oils being dear, it is very common to adulterate them feveral ways, to render them cheaper. These feveral ways feem reducible to three general kinds, each of which has its proper method of detection, viz. ft, With ex. preffed oils; 2d. With alcohol; and, 3d. With cheaper effential oils. If an effential oil be adul terated with an expressed oil, it is easy to discover the fraud, by adding a little fpirit of wine to a few drops of the suspected essential oil, and shaking them together; for the fpirit will diffolve all the oil that is effential, or procured by diftilla. tion, and leave all the expreffed oil, that was mixed with it, untouched. If an effential oil being the common table mustard. Certain dry matadulterated with alcohol, or rectified fpirit of wine, it may be done in proportion, up to that of an equal quantity, without being eafily discoverable either by by the fmell or tafte: the way to difcover this fraud, is to put a few drops of the oil into a glass of fair water; and if the oil be adulterated with fpirit, the water will immediately turn milky, and, by continuing to shake the glafs, the whole quantity of fpirit will be abforbed by the water and leave the oil pure at top. Finally, if an effential oil be adulterated by a cheaper effential oil, this is commonly done very artfully; the method is to put fir wood, turpentine, or oil of turpentine, into the ftill, along with the herbs to be diftilled for their oil, fuch as rofemary, lavender, origanum, &c. and by thefe means the oil of turpentine diftilled frome thefe ingredients comes over in great quantity, and inti mately blended with the oil of the genuine ingredient. The oils thus adulterated always difcover themselves in time, by their own flavour being overpowered by the turpentine fmell; but the ready way to detect the fraud, is to drench a piece of rag, or paper, in the oil, and hold it be fore the fire; for thus the grateful flavour of the plant will fly off, and leave the naked turpentine fcent behind. The virtues of oils, being the fame with those of the fubftances from whence they are obtained, may be learned under their several articles to which we refer. ii. OILS, EXPRESSED, are obtained from the feed, leaves, fruit, and bark of plants; thus, the feed of mustard, and of the fun flower, almonds, ters, as well as moift ones, may be made to af. ford oils by expreffion, by grinding them into a meal, which being fufpended to receive the va pour of boiling water, will thus be moistened fo as to afford an oil in the fame manner as almonds; and thus an oil may be procured from linfeed, hemp feed, lettuce-feed, white poppy-feed, &c. Oils obtained by expreffion fhould be fuffered to depurate themselves by ftanding in a moderately cool place, to feparate from their water, and depofit their faces; from both which they ought to be carefully freed. And if they are not thus rendered fufficiently pure, they may be washed well with fresh water, then thoroughly separated from it again by the feparating glafs, whereby they will be rendered bright and clear. iii. OILS OBTAINED BY INFUSION.. The next clafs of oils are thofe made by infufion or decoc. tion, wherein the virtues of fome herb or flower are drawn out in the oil; as the oils of rofes, chamomile, hypericum, alder, &c. However, thefe require to be differently treated: thus, for the fcented flowers, particularly rofes, infolation does bett; becaufe much boiling would exhale their more fragrant parts; but oils impregnated with green herbs, as thofe of chamomile and alder, require long boiling, before they receive the green colour defired. In general, no oils will bear to be boiled any longer than there remains fome aqueous humidity, without turning black. There are many compound oils prepared in the fame manner, viz. by boiling and infolation, and then ftraining off the oil for ufe. The fame con trivance |