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rent oils, and perhaps the fame oil in different states, differin this respect: fish oil, boiled to thickness, loll muchmore than that of linseed, the thick matter amountingonly to about one fourth of the original weight of the oil.

The workmen are accustomed to add, in the prepara-tion of ten or twelve gallons of oil, as soon as the burn-ing is over, a pound or two of dry crusts of bread, and adozen or two of onions, by which they suppose the greafi-ness to be more effectually destroyed. It may howeverbe questioned, whether additions of this kind are of muchuse; for I have prepared the varnish, seemingly of a verygood quality, by fire alone.

There is another fort of additions whose effect is moreapparent. To give a greater body to the varnish, and in-crease its drying quality, a proportion of turpentine isthought necessary; and with some artists, litharge has inthis intention been a secret. It is observed, in the Frenchencyclopedic, by Mr. le Breton, the printer of that work,that when very old oil is used, neither turpentine norlitharge are needful; but that, when the oil is new, someturpentine must necessarily be employed, for without it,the smearing of the paper, by the spreading or coming offof the ink, cannot be avoided; that it is much more eli-gible to use old oil than to have recourse to this correctionof the new, both turpentine and litharge, particularly thelast, making the mixture adhere so firmly to the types,that it is scarce to be got entirely off by the ley, whencethe eye of the letter is soon clogged up.

When turpentine is used, it is first boiled by itself,untill, on dipping in a piece of paper, it is found tocrumble and part from the paper when cold : the oil be-ing then taken from the fire, the turpentine, while stillfluid, is poured into it, after which the boiling is re-peated, and continued till they are sufficiently incorporated.

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