totally to diſappear, & the Liquor held againſt the Light would ſcarce ſeeme other than Cleer or Limpid, to any but an Attentive Eye, which is therefore remarkable; becauſe we know that Aqua-fortis corroding Copper, which is it that gives the Colour to Verdigreaſe, is wont to reduce it to a Green Blew Solution. But if into the other altogether or almoſt Colourleſs Liquor I was ſpeaking of, you drop a juſt quantity either of Oyl of Tartar or Spirit of Urine, you ſhall find that after the Ebullition is ceas'd, the mixture will diſcloſe a lively Colour, though ſomewhat differing from that which the Solution of Verdigreaſe had at firſt.
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,[a]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.
EXPERIMENT XLIII.
We took good common Vitriol, and having beaten it to Powder, and put it into a Crucible, we kept it melted in a gentle heat, till by the Evaporation of ſome parts, and the ſhuffling of the reſt, it had quite loſt its former Colour, what remain'd we took out, and found it to be a friable Calx, of a dirty Gray. On this we pour'd fair Water, which it did not Colour Green or Blew, but only ſeem'd to make a muddy mixture with it, then ſtopping the Vial wherein the Ingredients were put, we let it ſtand in a quiet place for ſome dayes, and after many hours the water having diſſolv'd a good part of the imperfectly calcin'd Body, the Vitriolate Corpuſcles ſwiming to and fro in the Liquor, had time by their opportune Occurſions to conſtitute many little Maſſes of Vitriol, which gave the water they impregnated a fair Vitriolate Colour; and this Liquor being pour'd off, the remaining dirty Powder did in proceſs of time communicate the like Colour, but not ſo deep, to a ſecond parcel of cleer Water that we pour'd on it. But this Experiment Pyrophilus is, (to give you that hint by the way) of too Luciferous a Nature to be fit to be
fully proſecuted, now that I am in haſte, and willing to diſpatch what remains. And we have already ſaid of it, as much as is requiſite to our preſent purpoſe.