sufficient to Destroy or Restore the Cæruleous Colour of our Tincture. But
whether concerning Liquors, wherein neither Acid nor Alcalisate Salts are
Eminently Prædominant, our Tincture will enable us to conjecture any thing
more than that such Salts are not Prædominant in them, I take not upon me
to determine here, but leave to further Tryal; For I find not that Spirit
of Wine, Spirit of Tartar freed from Acidity, or Chymical Oyl of
Turpentine, (although Liquors which must be conceiv'd very Saline, if
Chymists have, which is here no place to Dispute, rightly ascrib'd tasts to
the Saline Principle of Bodyes,) have any Remarkable Power either to
deprive our Tincture of its Cæruleous Colour, or restore it, when upon the
Affusion of Spirit of Vinegar it has disappear'd.

_EXPERIMENT XI._

And here I must not omit, _Pyrophilus_, to inform You, that we can shew You
even in a Mineral Body something that may seem very near of Kin to the
Changeable Quality of the Tincture of _Lignum Nephriticum_, for we have
several flat pieces of Glass, of the thickness of ordinary Panes for
Windows one of which being interposed betwixt the Eye and a clear Light,
appears of a Golden Colour, not much unlike that of the moderate Tincture
of our Wood, but being so look'd upon as that the Beams of light are not so
much Trajected thorough it as Reflected from it to the Eye, that Yellow
seems to degenerate into a pale Blew, somewhat like that of a Turquoise.
And what which may also appear strange, is this, that if in a certain
posture you hold one of these Plates Perpendicular to the Horizon, so that
the Sun-beams shine upon half of it, the other half being Shaded, You may
see that the part Shin'd upon will be of a much Diluter Yellow than the
Shaded part which will appear much more Richly Colour'd; and if You alter
the Posture of the Glass, so that it be not held Perpendicular, but
Parallel in reference to the Horizon, You may see, (which perhaps you will