Colour at all of their own. And that which deserves some particular wonder,
is, that the Cæruleous Tincture of our Wood is subject by the former
Method to be Destroy'd or Restor'd, the Yellowish or Reddish Tincture
continuing what it was. And that you may see, that Salts are of a
considerable use in the striking of Colours, let me add to the many
Experiments which may be afforded us to this purpose by the Dyers Trade,
this Observation; That as far as we have hitherto try'd, those Liquors in
general that are strong of Acid Salts have the Power of Destroying the
Blewness of the Infusion of our Wood, and those Liquors indiscriminatly
that abound with Sulphureous Salts, (under which I comprehend the Urinous
and Volatile Salts of Animal Substances, and the Alcalisate or fixed Salts
that are made by Incineration) have the vertue of Restoring it.

_A Corollary of the Tenth Experiment._

That this Experiment, _Pyrophilus_, may be as well Usefull as Delightfull
to You, I must mind You, _Pyrophilus_, that in the newly mention'd
Observation, I have hinted to You a New and Easie way of Discovering in
many Liquors (for I dare not say in all) whether it be an Acid or
Sulphureous Salt, that is Predominant; and that such a Discovery is
oftentimes of great Difficulty, and may frequently be of great Use, he that
is not a Stranger to the various Properties and Effects of Salts, and of
how great moment it is to be able to distinguish their Tribes, may readily
conceive. But to proceed to the way of trying other Liquors by an Infusion
of our Wood, take it briefly thus. Suppose I have a mind to try whether I
conjecture aright, when I imagine that Allom, though it be plainly a Mixt
Body, does abound rather with Acid than Sulphureous Salt. To satisfie my
self herein, I turn my back to the Light, and holding a small Vial full of
the Tincture of _Lignum Nephriticum_, which look'd upon in that Position,
appears Cæruleous, I drop into it a little of a strong Solution of Allom