And I shall now
add, that I have Learn'd from one of the Chief Artificers that sells
Painted Glass, that those of his Trade Colour it Yellow with a preparation
of the _Calx_ of Silver. Though having lately had occasion among other
Tryals to mingle a few grains of Shell-silver (such as is imploy'd with the
Pensil and Pen) with a convenient proportion of powder'd Crystal Glass,
having kept them two or three hours in fusion, I was surpriz'd to find the
Colliquated Mass to appear upon breaking the Crucible of a lovely Saphirine
Blew, which made me suspect my Servant might have brought me a wrong
Crucible, but he constantly affirm'd it to be the same wherein the Silver
was put, and considerable Circumstances countenanc'd his Assertion, so that
till I have opportunity to make farther Tryal, I cannot but suspect, either
that Silver which is not (which is not very probable) brought to a perfect
Fusion and Colliquation with Glass, may impart to it other Colours than
when Neal'd upon it, or else (which is less unlikely) that though Silver
Beaters usually chuse the finest Coyn they can get, as that which is most
extensive under the Hammer, yet the Silver-leaves of which this Shel-silver
was made, might retain so much Copper as to enable it to give the
predominant tincture to the Glass.
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