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with much dark smoak; but if you will try them in a Spoon, heat it first over a Candle, and then blow the flame of lighted paper, or of a Wax Candle on them. To try the scent, blow out the flame of the good Oyls, and your smell will soon discover the ill scent of the Turpentine from that of the good Oyl. But on the contrary, all Oyls drawn from Plants by distillation hardly flame, and the flame soon goes out, and the smoak gives a full flavour of the Plant it self, whereas those sophisticated as before, differ from the true in both. The same Oyls are also sophisticated with cheap ones drawn from decayed Oringes, and Limons; Your smell on firing will soon discover these mixtures. A third way of sophisticating Chymical Oyls is, by mixing with them such Oyls as are made by expression, which are easily discovered by rubbing them on white paper, which being held and dryed at the fire, the Chymical part soon flyes away, and leaves the paper transparent, looking no otherwise then oyled paper; but pure Chymical Oyls totally fly away, leaving the paper white as 'twas before, and not transparent, and in this way Oyl of sweet Almonds and Spike have a great share. As for Oyls drawn by Retort, they all of them smell so strong of the fire, that neither smell nor tast can well discover any fraud in them. Now for the fixed Salts, most of them are made of the Ashes of Tobacco-stalks, &c. More might be said for the discovery of the Cheats of other Chymical preparations, which shall be reserved to another opportunity, and had Physicians just encouragement, they would spend both their time and moneys on the like discoveries for the publick Utility.
