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.