_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.
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