Experiment XLI
Of Kin to the last or fortieth Experiment is another which I remember I have sometimes shewn to Virtuosi that were pleas’d not to dislike it. I took Spirit of Urine made by Fermentation, and with a due proportion of Copper brought into small parts, I obtain’d a very lovely Azure Solution, and when I saw the Colour was such as was requisite, pouring into a clean Glass, about a spoonfull of this tincted Liquor, (of which I us’d to keep a Quantity by me,) I could by shaking into it some drops of Strong Oyl of Vitriol, deprive it in a trice of its Deep Colour, and make it look like Common-water.
Annotation.
This Experiment brings into my mind this other, which oftentimes succceds well enough, though not quite so well as the former; Namely, that if into about a small spoonfull of a Solution of good French Verdigrease made in fair Water, I drop’t and shak’d some strong Spirit of Salt, or rather deflegm’d Aqua Fortis, the Greenness of the Solution would be made in a trice almost 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.