SECOND EDITION. V

the glazed windows of the ancients,
having asserted, (p. 77), " glass for
windows was then unknown," and
soon after Pliny mentions the glazed
windows of the portico of the atri-
um: The substance used by the
ancients for this purpose was not
glass, similar to what is now vised,
but a stone called lapis specularis,
a species of talc, according to Pliny's
Natural History; which easily spirt-
ing into thin transparent plates or
laminae, was fit for the purpose: it
has a similar application now, for
objects to be viewed by the micro-
scope.