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.

_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