ot now the leisure to
discourse. And for the same reason, though I could add many other
Instances, of what I formerly noted touching the emergency of Redness upon
the Digestion of many Bodies, insomuch that I have often seen upon the
Borders of _France_ (and probably we may have the like in _England_) a sort
of Pears, which digested for some time with a little Wine, in a Vessel
exactly clos'd, will in not many hours appear throughout of a deep Red
Colour, (as also that of the Juice, wherein they are Stew'd, becomes) but
ev'n on pure and white Salt of Tartar, pure Spirit of Wine, as clear as
Rock-water, will (as we elsewhere declare) by long Digestion acquire a
Redness; Though I say such Instances might be Multiply'd, and though there
be some other Obvious changes of Colours, which happen so frequently, that
they cannot but be as well Considerable as Notorious; such as is the
Blackness of almost all Bodies burn'd in the open Air: yet our haste
invites us to resign you the Exercise of enquiring into the Causes of these
Changes. And certainly, the reason both _why_ the Soots of such differing
Bodies are almost all of them all Black, _why_ so much the greater part of
Vegetables should be rather Green than of any other Colour, and
particularly (which more directly concerns this place) _why_ gentle Heats
do so frequently in Chymical Operations produce rather a Redness than
another Colour in digested _Menstruums_, not only Sulphureous, as Spirit of
Wine, but Saline, as Spirit of Vinegar, may be very well worth a serious
Inquiry; which I shall therefore recommend to _Pyrophilus_ and his
Ingenious Friends.

[21] _Parkinson_, Thea. Bot. Trib. 4 cap. 12.

_EXPERIMENT XXXVII._

It may seem somewhat strange, that if you take the Crimson Solution of
_Cochineel_, or the Juice of Black Cherries, and of some other Vegetables
that afford the like Colour, (which because many take but for a deep Red,
we do with them sometimes call it so) and let some of it fall upon a piece
of Paper, a drop or two of an Acid Spirit, such as Spirit of Salt, or
_Aqua-fortis_, will immediately turn it into a fair Red. Whereas if you
make an Infusion of Brazil in fair Water, and drop a little Spirit of Salt
or _Aqua-fortis_ into it, that will destroy its Redness, and leave the
Liquor of a Yellow, (sometimes Pale) I might perhaps plausibly enough say
on this occasion, that if we consider the case a little more attentively,
we may take notice, that the actio