like a little Flagg. This Leaf being held
very near the Eye, and obverted to the Light, appear'd so full of Pores,
that it seem'd to have such a kind of Transparency as that of a Sive, or a
piece of Cyprus, or a Love-Hood; but the Light that pass'd by these Pores
was in its Passages So Temper'd with Shadow, and Modify'd, that the Eye
discern'd no more a Golden Colour, but a Greenish Blew. And for other's
satisfaction, we did in the Night look upon a Candle through such a Leaf of
Gold; and by trying the Effect of Several Proportions of Distance betwixt
the Leaf, the Eye and the Light, we quickly hit upon such a Position for
the Leaf of Gold, as that the flame, look'd on through it, appear'd of a
Greenish Blew, as we have seen in the Day time. The like Experiment try'd
with a Leaf of Silver succeeded not well.

* * * * *

_EXPERIMENT X._

We have sometimes found in the Shops of our Druggists, a certain Wood,
which is there called _Lignum Nephriticum_, because the Inhabitants of the
Country where it grows, are wont to use the Infusion of it made in fair
Water against the Stone of the Kidneys, and indeed an Eminent Physician of
our Acquaintance, who has very Particularly enquir'd into that Disease,
assures me, that he has found such an Infusion one of the most effectual
Remedyes, which he has ever tried against that formidable Disease. The
ancientest Account I have met with of this Simple, is given us by the
Experienc'd _Monardes_ in these Words. _Nobis,_ says he,[16] _Nova Hispania
mittit quoddam ligni genus crassum & enode, cujus usus jam diu receptus
fuit in his Regionibus ad Renum vitia & urinae difficultates ac arenulas
pellendas. Fit autem hac ratione, Lignum assulatim & minutim concisum in
limpidissima aqua fontana maceratur, inque ea relinquitur, donec aqua a
bibentibus absumpta sit, dimidia hora post injectum lignum aqua caeruleum
colorem contrabit, qui sensim intenditur pro temporis diuturnitate, tametsi
lignum candidum fit_. This Wood, _Pyrophilus_, may afford us an Experiment,
which besides the singularity of it, may give no small assistance to an
attentive Considerer towards the detection of the Nature of Colours. The
Experiment as we made it is this. Take _Lignum Nephriticum_, and with a
Knife cut it into thin Slices, put about a handfull of these Slices into
two three or four pound of the purest Spring-water, let them infuse there a
night, but if you be in hast, a much shorter