The Experiment I am now to mention to you, _Pyrophilus_, is that which both
you, and all the other _Virtuosi_ that have seen it, have been pleas'd to
think very strange; and indeed of all the Experiments of Colours, I have
yet met with, it seems to be the fittest to recommend the Doctrine propos'd
in this Treatise, and to shew that we need not suppose, that all Colours
must necessarily be Inherent Qualities, flowing from the Substantial Forms
of the Bodies they are said to belong to, since by a bare Mechanical change
of Texture in the Minute parts of Bodies; two Colours may in a moment be
Generated quite _De novo,_ and utterly Destroy'd. For there is this
difference betwixt the following Experiment, and most of the others
deliver'd in these Papers, that in this, the Colour that a Body already
had, is not chang'd into another, but betwixt two Bodies, each of them
apart devoid of Colour, there is in a moment generated a very deep Colour,
and which if it were let alone, would be permanent; and yet by a very small
Parcel of a third Body, that has no Colour of its own, (lest some may
pretend I know not what Antipathy betwixt Colours) this otherwise permanent
Colour will be in another trice so quite Destroy'd, that there will remain
no foot-stepts either of it or of any other Colour in the whole Mixture.

The Experiment is very easie, and it is thus perform'd: Take good common
Sublimate, and fully satiate with it what quantity of Water you please,
Filtre the Solution carefully through clean and close Paper, that it may
drop down as Clear and Colourless as Fountain water. Then when you'l shew
the Experiment, put of it about a Spoonfull into a small Wine-glass, or any
other convenient Vessel made of clear Glass, and droping in three or four
drops of good Oyl of Tartar, _per Deliquium_; well Filtred that it may
likewise be without Colour, these two Limpid Liquors will in the twinkling
of an Eye turn into an Opacous mixture of a deep Orange Colour, which by
keeping the Glass continually shaking in your hand, you must preserve from
setling too soon to the Bottom; And when the Spectators have a little