omewhat wonder at)
That so much does the Colour depend upon the Texture resulting from the
Convention of the several sorts of Corpuscles, that though in out
Experiment, Oyl of Vitriol destroys the Yellow Colour, yet with
_Quick-silver_ and fair Water, by the help of Oyl of Vitriol alone, we may
easily make a kind of Precipitate of a fair and permanent Yellow, as you
will e're long (in the forty second Expement of this third Part) be taught.
And I may further add, that I chose Oyl of Vitriol, not so much for any
other or peculiar Quality, as for its being, when 'tis well rectify'd,
(which 'tis somewhat hazardous to bring it to be) not only devoid of Colour
and in Smells, but extremely Strong and Incisive; For though common and
undephlegmated _Aqua-fortis_ will not perform the same thing well, yet that
which is made exceeding Strong by being carefully Dephlegm'd, will do it
pretty well, though not so well as Oyl of Vitriol which is so Strong, that
even without Rectification it may for a need be made use of. I will not
here tell you what I have try'd, that I may be able to deprive at pleasure
the Precipitate that one of the Sulphureous Liquors had made, by the
copious Affusion of the other: Because I found, though this Experiment is
too ticklish to let me give a full account of it in few words, I shall
therefore tell you, that it is not only for once, that the other
above-mention'd Experiment may be made, the same Numerical parcels of
Liquor being still imploy'd in it; for after I have Clarify'd the Orange
Colour'd Liquor, by the addition of as little of the Oyl of Viriol as will
suffice to perform the effect, I can again at pleasure re-produce the
Opacous Colour, by the dropping in of fresh Oyl of Tartar, and destroy it
again by the Re-affusion of more of the Acid _Menstruum_; and yet oftner if
I please, can I with these two contrariant Liquors recall and disperse the
Colour, though by reason of the addition of so much new Liquor, in
reference to the Mercurial particles, the Colour will at length appear more
dilute and faint.

_An improvement of the fortieth Experiment_.

And, _Pyrophilus_, to confirm yet further the Notions that led me to think
on the propos'd Experiment, I shall acquaint you with another, which when I
had conveniency I have sometimes added to it, and which has to the
Spectators appear'd little less Odd than the first; And though because the
Liquor, requisite to make the Trial succeed well, must be on pu