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Updated: May 1, 2025
For in the making of these, though pure Sand or Calcin'd Crystal give the Body, yet 'tis for the most part some Metalline or Mineral Calx, mingled in a small proportion that gives the Colour.
Tin Corroded by Aqua-fortis till the Menstruum will work no farther on it, becomes exceeding White, but as we elsewhere note, does very easily of it self acquire the consistence, not of a Metalline Calx, but of a Coagulated matter, which we have observ'd with pleasure to look so like, either to curdled Milk, or curdled Whites of Eggs, that a person unacquainted with such Solutions may easily be mistaken in it.
And with the same White Calx and a little Fair Water we likewise Stain'd the White Hafts of Knives, with a lasting Black in those parts where the Calx was Plentifully enough laid on, for where it was laid on but very Thinly, the Stain was not quite of so Deep a Colour.
I also told you not long since, that if you corrode Quick-silver with Oyl of Vitriol instead of Aqua-fortis, and abstract the Menstruum, there will remain a White Calx which by the Affusion of Fair Water presently turns into a Lemmon Colour. And ev'n the Succedaneum to a Menstruum may sometimes serve the turn to change the Colours of a Metal.
And you'l easily believe, that in many changes of Colour, that happen upon the Dissolutions of Metalls, and Precipitations made with Oyl of Tartar, and the like Fix'd Salts, there may Intervene a Coalition of Saline Corpuscles with the Particles of the Body Dissolv'd or Precipitated, if you examine how much the Vitriol of a Metall may be Heavier than the Metalline part of it alone, upon the Score of the Saline parts Concoagulated therewith, and, that in Several Precipitations the weight of the Calx does for the same Reason much exceed that of the Metall, when it was first put in to be Dissolv'd.
And divers Alchymists, when they make Solutions of Minerals they would Examine, are very Glad, if they see a Black Powder Præcipitated to the Bottom, taking it for a Hopefull Sign, that those Particles are of a Golden Nature, which appear in a Colour so ordinary to Gold parted from other Metalls by Aqua Fortis, that it is a trouble to the Refiner to Reduce the Præcipitated Calx to its Native Colour.
And to shew you, that there is likewise in Allom a Body, with which the fix'd Salt of the Alcalizate Solution will concoagulate into a Saline Substance differing from either of them, I shall add, that I have taken pleasure to recover out of the slowly exhal'd Liquor, that pass'd through the filtre, and left the foremention'd Calx behind, a Body that at least seem'd a Salt very pretty to look on, as being very White, and consisting of an innumerable company of exceeding slender, and shining Particles, which would in part easily melt at the flame of a Candle, and in part flye away with some little noise.
And other Examples might be added of this way of producing Whiteness in Bodyes by Præcipitating them out of the Liquors wherein they have been Dissolv'd; but I think it may be more usefull to admonish you, Pyrophilus, that this observation admits of Restrictions, and is not so Universal, as by this time perhaps you have begun to think it; For though most Præcipitated Bodyes are White, yet I know some that are not; For Gold Dissolv'd in Aqua Regis, whether you Præcipitate it with Oyl of Tartar, or with Spirit of Sal Armoniack, will not afford a White but a Yellow Calx.
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.
It seems to this noble author that the glossopetrae should be classed in the animal kingdom, because, being burnt, they are changed into cinders as bones, before they are reduced into a calx or ashes, whilst calcined stones are immediately reduced into a calx.
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