those of other Bodies; but Mineral Pigments may be mingled by fire little
less regularly and successfully, than in ordinary Dyeing Fatts, the vulgar
Colours are wont to be mingled by the help of Water.

_Annotation III._

'Tis not only Metalline, but other Mineral Bodies, that may be imploy'd, to
give Tinctures unto Glass (and 'tis worth noting how small a quantity of
some Mineral substances, will Tinge a Comparatively vast proportion of
Glass, and we have sometimes attempted to Colour Glass, ev'n with Pretious
Stones, and had cause to think the Experiment not cast away. And 'tis known
by them that have look'd into the Art of Glass, that the Artificers use to
tinge their Glass Blew, with that Dark Mineral _Zaffora_, (some of my
Tryals on which I elsewhere acquaint you) which some would have to be a
Mineral Earth, others a Stone, and others neither the one, nor the other,
but which is confessedly of a Dark, but not a Blew Colour, though it be not
agreed of what particular Colour it is. 'Tis likewise though a familiar yet
a remarkable practise among those that Deal in the making of Glass, to
imploy (as some of themselves have inform'd me) what they call Manganess,
and some Authors call _Magnesia_ (of which I make particular mention in
another Treatise) to exhibit in Glass not only other Colours than its own,
(which is so like in Darkness or blackishness to the Load stone, that 'tis
given by Mineralists, for one of the Reasons of its Latine Name) but
Colours differing from one another. For though they use it, (which is
somewhat strange) to Clarifye their Glass, and free it from that Blewish
Greenish Colour, which else it would too often be subject to, yet they also
imploy it in certain proportions, to tinge their Glass both with a Red
colour, and with a Purplish or Murry, and putting in a greater Quantity,
they also make with it that deep obscure Glass which is wont to pass for
Black, which agrees very well with, and may serve to confirm what we noted