Take Oil of Amber, or any ſuch ſtinking Oil, put it into a glaſs retort, the fourth part only being full, poure on it drop by drop the Spirit of Salt, (or any other acid Spirit) and they will boil together; and when ſo much of the Spirit is poured on that it boileth no more, then ceaſe and diſtill it. Firſt cometh over a ſtinking water, then a clear white, well ſmelling Oil, and after that a yellow Oil which is indifferent good: but the ſpirit of Salt hath loft its ſharpness: the volatile Salt of the Oil remaineth coagulated with the Spirit of Salt, and is black, and taſteth like ſalt Armoniack, and hath no ſmell being ſublimed from it. Now the reaſon of all this is, becauſe the volatile ſalt of the Oil which is the cauſe of the ſtink thereof, is fixed by the acid Spirit of the Salt: for acid Spirits, and volatile Salts are contrary the one to the other, and ſpirit of Urine or any volatile ſalt will precipitate any metall as well as ſalt of Tartar.
Theſe Oils will remain clear, and have far more vertue, then the ordinary fort of Oils have.
As for common ordinary diſtilled Oils, they need not, if they be wel ſeparated from the water with which they were diſtilled, any rectifying at all; and if you goe about to rectifie them, you will looſe good part of them, and make that which remains not at all the better. But if there be any better then another for rectifying of them it is by digeſtion, by which means there will be a ſeparation of what is flegmatick which you may ſeparate afterwards, and by this means you ſhall looſe none of the Oils.
