Secondly, That nevertheless this Colour may be easily over-powr'd by those
of divers other Mineral Pigments (if I may so call them) so that with a
glass of Lead, you may Emulate (for Instance) the fresh and lovely
Greenness of an Emerald, though in divers cases the Colour which the Lead
it self upon Vitrification tends to, may vitiate that of the Pigment, which
you would introduce into the Mass.
Thirdly, That so much ev'n these Colours depend upon Texture, that in the
Glass of Lead it self made of about three parts of _Lytharge_ or _Minium_
Colliquated with one of very finely Powder'd Crystal or Sand, we have taken
pleasure to make the mixture pass through differing Colours, as we kept it
more or less in the Fusion. For it was not usually till after a pretty long
Decoction that the Mass attain'd to the Amethystin Colour.
Fourthly and lastly, That the degrees of Coction and other Circumstances
may so vary the Colour produc'd in the same mass, that in a Crucible that
was not great I have had fragments of the same Mass, in some of which
perhaps not so big as a Hazel-Nut, you may discern four distinct Colours.
_Annotation VI._
You may remember (_Pyrophilus_) that when I mention'd the three sorts of
adventitious Colours of Metals, I mention'd them but as the chief, not the
only.
Pages:
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333