erical_ or _globular_ form, which propriety and several of the
_Phaenomena_ that proceed from it, I have more fully explicated in the
sixth Observation.

One Experiment, which does very much illustrate my present Explication, and
is in it self exceeding pretty, I must not pass by: And that is a way of
making small _Globules_ or _Balls_ of Lead, or Tin, as small almost as
these of Iron or Steel, and that exceeding easily and quickly, by turning
the filings or chips of those Metals also into perfectly round _Globules_.
The way, in short, as I received it from the _Learned Physitian Doctor_
I.G. is this;

Reduce the Metal you would thus shape, into exceeding fine filings, the
finer the filings are, the finer will the Balls be: _Stratifie_ these
filings with the fine and well dryed powder of quick Lime in a _Crucible_
proportioned to the quantity you intend to make: When you have thus filled
your _Crucible_, by continual _stratifications_ of the filings and powder,
so that, as neer as may be, no one of the filings may touch another, place
the _Crucible_ in a _gradual fire_, and by degrees let it be brought to a
heat big enough to make all the filings, that are mixt with the quick Lime,
to melt, and no more; for if the fire be too hot, many of these filings
will joyn and run together; whereas if the heat be proportioned, upon
washing the Lime-dust in fair Water, all those small filings of the Metal
will subside to the bottom in a most curious powder, consisting all of
exactly round _Globules_, which, if it be very fine, is very excellent to
make Hour-glasses of.

Now though quick Lime be the powder that this direction makes choice of,
yet I doubt not, but that there may be much more convenient ones found out,
one of which I have made tryal of, and found very effectual; and were it
not for discovering, by the mentioning of it, another Secret, which I am
not free to impart, I should have here inserted it.

* * * * *

Observ. IX. _Of the Colours observable in Muscovy Glass, and other thin
Bodies_.

Moscovy-glass, or _Lapis specularis_, is a Body that seems to have as many
Curiosities in its Fabrick as any common Mineral I have met with: for
first, It is transparent to a great thickness: Next, it is compounded of an
infinite number of thin flakes joyned or generated one upon another so
close & smooth, as with many hundreds of them to make one smooth and thin
Plate of a transparent flexible