OIL

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face, caufe them to fliine in the dark withoutany rilk of injury from the flow combudion ofthis highly inflammable l'ubftance. If the oilhas been charged with phofphorus at a boilingheat, a portion of this latter depofits by coolingin obtohedral cry Hals. Phofphorized oil whendiftilled affords pliofphuretted hydrogen gas.

Sulphur is eafily and largely foluble in boilingoil: the compound has a thick foinewhat vifcidconfidence, and a deep red colour, hence it wasformerly named ruby of fubphitr. When highlycharged with fulphur at a boiling heat, itdepofits a part by cooling: if this takes placerapidly the fulphur is in the form of needles,if more flowly it forms octoheciral cryftals.

Sulphurized oil has a ftrong fetid odour,and when diftilled gives out a large quantity offulphuretted hydrogen.

Moft metallic oxyds are decompofed by thefixed oils at a boiiing heat: thofe however thatare commonly employed for this purpofe areminium and litharge. If either of thefe fub-ftances ground to a very fine powder, be put ina kettle with a little water and fome fat oil, andthe whole be well mingled by conftant ftirring,it will be found that the oil when nearly at thetemperature of boiling water, firft abftra&s partof the oxygen from the oxyd, and then diflblvespretty rapidly the oxyd itfelf. In confequence ofthis the oil becomes thick and coloured, acquiresa peculiar odour, and when cooled becomesopake, and of a foft pally confidence. By con-tinuing the heat after tlje folution of the oxyd,till the water is compleatly driven off, the refi-due on cooling acquires nearly the confidenceof wax, and is known in pharmacy by the appel-lation of plafer. If inftead of fat oil, drying oilbe made ufe of, the mixture cannot be madeharder than ftiff pafte. Deyeux b has fhewnthat the fat oils when previoufly mixed withmucilage, are exa£tly fimilar in this refpebl tothe drying oils. Plaftcr Is not foluble either■in alcohol or water, in which refpedt it differsmaterially from the proper foaps, to which ithas been compared by fome cbemifts. If afterthe oil and litharge have combined together the"water is poured off, inftead of being diffipatedfiy a further continuation of the heat, and thenevaporated confiderably in a feparate veflel, itwill be found to have, acquired a thick fyrupyconfidence and a faccharine tafte. The dif-covery of this peculiar fweet matter is due to,, c fi?’ f r . om whofe experiments on the fubjecltile lollowing particulars are extracted. c

t is neither cryftallizable nor fufceptible of

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fermentation: if prepared with perfectly frefhoil it appears to contain no lead, but if rancidoil has been made ufe of, it yields a precipitateof fulphated lead with fulphuric acid. If afterbeing iufpifiated it is ftrongly heated, the va-pours that arife will take fire on the applicationof a candle. By deftruftive didillation re-peated two or three times at a temperatureequal to that required for the volatilization offulphuric acid, it is decompofed into brownempyreumatic oil, and a light fpungy coal, car-buretted hydrogen being probably given off atthe fame time. By repeated abftracdion withnitric acid it is at length converted into oxaliiacid.

If the naturally drying oils are boiled upona fmall quantity of litharge without the inter-vention of water, they become thick and gluti-nous, and more drying than before. Not onlythe oxyds, but alfo aqueous dilutions of theacetite of lead, as well as the fulphat of zinc,are employed for this purpofe.

The alkalies, both fixed and volatile, and the'alkaline earths when perfectly cauftic, a£t withenergy upon all the fixed oils, but more efpeci-ally on the fat ones, forming with them Soapsof various qualities ; for an account of whichthe reader is referred to that article.

The ablion of the ftronger acids upon oils isvery remarkable, on which account we lhalltreat of it with fome minutenefs.

The compound produced by the mutual a£tionof fixed oil and fulphuric acid, improperly calledan acid foap, has been examined by Achard dwith the following refults. To prepare thiscompound, put 7 parts of concentrated fulphuricacid into a porcelain mortar, and add drop bydrop 8 parts of oil heated nearly to ebullition,taking care to dir the whole conftantly duringthe procefs : if the oil is added too quicklyan eftervefcence takes place accompanied bythe fuffbeating odour of fulphureous acid, butthis mud be carefully avoided. The com-pound when recently prepared is of a blackcolour, and nearly of the confidence of thick tar,but by walhing thoroughly in 6 parts of diftilledwater the oil afl'umes nearly the appearance ofbrown wax : if it is dill acidulous to the tade,repeat the wadiing in fucceffive fmall quantitiesof water, till the lad no longer exhibits anyfigns of uncombined acid. The oil becomesconfiderably heavier by this treatment, not un-frequently finking in water: it is folid an dbrittle, lias a peculiar odour, is perfectly folublein alcohol, and with water makes an opalefceni

* Ann. deChem, xxxiii. p. 55,. « Eff. p. 364, * Journ. de Phyf. xvi. p. 411-

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vol. n.