Experiment XLII
That the Colour (Pyrophilus) of a Body may be chang’d by a Liquor which of it ſelf is of no Colour, provided it be Saline, we have already manifeſted by a multitude of inſtances. Nor doth it ſeem ſo ſtrange, becauſe Saline Particles ſwimming up and down in Liquors, have been by many obſerv’d to be very operative in the Production and change of Colours. But divers of our Friends that are not acquainted with Chymical Operations have thought it very ſtrange that a White Body, and a Dry one too, ſhould immediately acquire a rich new Colour upon the bare affuſion of Spring-Water deſtitute as well of adventitious Salt as of Tincture. And yet (Pyrophilus) the way of producing ſuch a change of Colours may be eaſily enough lighted on by thoſe that are converſant in the Solutions of Mercury. For we have try’d, that though by Evaporating a Solution of Quick-Silver in Aqua-fortis, and abſtracting the Liquor till the remaining matter began to be well, but not too ſtrongly dryed, fair Water pour’d on the remaining Calx made it but ſomewhat Yellowiſh; yet when we took good Quick-Silver, and three or four times its weight of Oyl of Vitriol, in caſe we in a Glaſs Retort plac’d in Sand drew off the Saline Menſtruum from the Metalline Liquor, till there remain’d a dry Calx at the bottome, though this Precipitate were a Snow White Body, yet upon pouring on it a large quantity of fair Water, we did almoſt in a moment perceive it to paſs from a Milky Colour to one of the lovelieſt Light Yellows that ever we had beheld. Nor is the Turbith Mineral, that Chymiſts extol for its power to Salivate, and for other vertues, of a Colour much inferiour to this, though it be often made with a differing proportion of the Ingredients, a more troubleſome way. For Beguinus,22 who calls it Mercurius præcipitatus optimus, takes to one part of Quick-Silver, but two of Liquor, and that is Rectifi’d Oyl of Sulphur, which is (in England at leaſt) far more ſcarce and dear than Oyl of Vitriol; he alſo requires a previous Digeſtion, two or three Cohobations, and frequent Ablutions with hot Diſtill’d Water, with other preſcriptions, which though they may conduce to the Goodneſs of the Medicine, which is that he aims at, are troubleſome, and, our Tryals have inform’d you unnecceſſary to the obtaining the Lemmon Colour which he regards not. But though we have very rarely ſeen either in Painters Shops, or elſewhere a finer Yellow than that which we have divers times this way produc’d (which is the more conſiderable, becauſe durable and pleaſant Yellows are very hard to be met with, as may appear by the great uſe which Painters are for its Colours ſake fain to make of that pernicious and heavy Mineral, Orpiment) yet I fear our Yellow is too coſtly, to be like to be imploy’d by Painters, unleſs about Choice pieces of Work, nor do I know how well it will agree with every Pigment, eſpecially, wich Oyl’d Colours. And whether this Experiment, though it have ſeem’d ſomewhat ſtrange to moſt we have ſhown it to, be really of another Nature than thoſe wherein Saline Liquors are imploy’d, may, as we formerly alſo hinted, be ſo plauſibly doubted, that whether the Water pour’d on the Calx, do barely by imbibing ſome of its Saline parts alter its Colour by altering its Texture, or whether by diſſolving the Concoagulated Salts, it does become a Saline Menſtruum, and, as ſuch, work upon the Mercury, I freely leave to you (Pyrophilus) to conſider. And that I may give you ſome Aſſiſtance in your Enquiry, I will not only tell you, that I have ſeveral times with fair Water waſh’d from this Calx, good ſtore of ſtrongly taſted Corpuſcles, which by the abſtraction of the Menſtruum, I could reduce into Salt; but I will alſo ſubjoyn an Experiment, which I devis’d, to ſhew among other things, how much a real and permanent Colour may be as it were drawn forth by a Liquor that has neither Colour, nor ſo much as Saline or other Active parts, provided it can but bring the parts of the Body it imbibes to convene into cluſters diſpos’d after the manner requiſite to the exhibiting of the emergent Colour. The Experiment was this.