O I L

O I L

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It is ufcd both for food and in the compofitionof varnifhes, but is very unfit to burn in a lamp.Linfeed Oil.

The feeds of the common flax, from whichthis oil is produced, confift of a white kernelcovered by a thin brownifh fhell. As it isimpoifible to feparate the (hell from the kernel,the entire feed mull be fubmitted to the prefs,but if thus treated without any previous prepa-ration, the quantity of oil obtained is compara-tively fmall on account of a ftrong mucilagethat refides in the fhell, and abforbs a largeproportion of the oil as it is forced out of thekernel. For this reafon, and becaufe the colddrawn oil is not fo fit for the purpofes to whichlinfeed oil is generally applied as that which ishot drawn, the following method is generallytaken to deftroy the mucilage before the appli-cation of the prefs. An iron vefiel like a fand-bath, and capable of containing fome bufhels,is fixed in a furnace: it is then filled withlinfeed and heated by a moderate fire, carebeing taken to ftir up its contents from time totime, that every part may be equally roafted;at firft there arifes an abundance of aqueousvapour, which as the heat is increafed isfollowed by denfe blackifh fumes of a verynaufeous odour. The torrefadfion being com-pleated, the pafte is prefled in the mill in theufual way.

The proportion of oil yielded by this feed isabout 20 per cent: its ip. gr. is =0.9403.It is not congealed except by a cold belowo° Fahr. its point of ebullition is about 6oo° ofthe fame thermometer. The cold drawn oilhas a high yellow colour, is very undluous andunpleafant both to the tafte and fmell; by ex-pofure to the air and light it becomes drying.The hot drawn oil is of a high yellowifh red ordeep wine colour, it is ftill more naufeous thanthe former; it is of a thicker confiitence, anddries without much difficulty in the air, moreefpecially if it has been boiled with a littlelitharge. Linfeed oil is employed a little inmedicine, but the great demand for it is in thecoarfer kinds of painting, particularly fuch asis not much expofed to the weather, as floorcloths, &c.

Hempfeed Oil.

This oil is of a green colour and is ftronglyimpregnated with the peculiar odour of theplant. The proportion of oil that hempfeedaffords is from .20 to 25 per cent. In itsgeneral properties, ufes, and mode of prepara-tion it clofely refcmbles the preceeding.

Oils ef Mujlard-feed , Cole-feed , Rape-feed, andSutiflonver-Seed.

Thefe oils are lefs coloured and lefs highlyflavoured than the two preceeding, they arevery little liable to dry by expofure to the air,which, together with their moderate price,induces a large confumption of them by thewool-dreflers in order to preferve the wool fromthe attacks of moths and other infedts; and bythe leather dreflers.

Nut-Oil.

This is obtained chiefly by cold drawing fromthe kernels either of the walnut or of the hazlenut. In the warm climate of the South ofEurope thefe fruits come to their full perfedtion,and will yield by proper management full halftheir weight of oil. Recent cold drawn nutoil is by many preferred to olive oil, on accountof the exquifite nut flavour which it retains: thehot drawn has an empyreumatic tafte, and is nolonger fit for the table; it is however in highrequeft by the painter, as being eminentlydrying, much lefs coloured than linfeed oil,,and capable of bearing the injuries of theweather better than any other oil.

Beech-nut Oil.

Several inefl'edfual attempts have been made-to manufacture this oil with profit from EnglilhBeech maft. Various cauies have probablyconcurred to occafion the failure, particularlythe inexpertnefs in the method of extradiion,,and in all probability a real defedt of oil compa-red to that contained in the beech nuts ofFrance and the South of Germany . The fol-lowing is the method adopted by fome manu-fadlurers, ai^d appears upon the whole to bethe belt. The nuts when feparated from theouter prickly receptacle are palled through amill, the ftones of which are fet fufticientlywide to break off the outer fhell without mate-rially bruifing the kernel, after which by meansof the common winnowing machine the fhellsare got rid of. The decorticated nuts are thenthrown into fcalding water, and all thofe thatfwim are rejedted as being mouldy and wormeaten, and therefore communicating a bad tafteto the oil: the reft are reduced to a pulp, andthen cold drawn, when they will be found toyield 15 per cent, -of a clear light colourednearly infipid oil, to the full as good as commonolive oil. The marc being now Rightly torrefiedand again preffed, will afford 12 per cent, moree f an inferior oil, and the dry refidue is anexcellent food for cattle, much better thancommon oil cake.