Evening star. [volume] (Washington, D.C.) 1854-1972, 1879-11-08
Iridescesat Glass.
THE REVIVAL OF ONE OF THE LOST ARTS OF OLD
ROMAN DAYS

1t is not generally known, says the Boston
Cof.niel cfdt Bulletin, that the beautiful vases
and other forms Of irtdescent glass, which have
recently begun to adOrn the windows of our
chinaware dealers, mark the revival Of one OF
OF the lost arts OF old Roman days. Most OF the
old glass brought TO light from the buried cities
of Pompeii and Herculaneum, from Roman
tombs, and more recently from the treasures OF
the Cypriote cities or temples, possesses this
curious property of iridescence, by means of
which it reflects light with all the colors of the
rainbow. There has been some dispute as to
whether this glass was iridescent when made.
or whether 1t acquired this quality subsequently
by some natural agency. The more reasonable
the celebrated French chemist, Is that the glass
originally plain, became irideScent from long
exposure to the action of the air and moisture
| at high temperature, these conditions being
admirably fulfilled in the old Roman tombS
where most of the glass is found. All glass has
conditions; but in some kinds this tendency is
more strongly marked than In others. In glass
for optical instruments a tendency to become
iridescent is serious fault and different kinds
Of glass are combined to form a perfect color
less lens. Modern chemists and glaSsmaAerS
have long been trying to discover the art of
making glass irideScent by some more speedy
means than that of burying it in damp soil
for the benefit of a thanklesS posterity. With
all the progress made in kindred branches OF
the art, nothing Of note was done in this direc
ton until two French chemists quite re-
Gently succeeded in arttticially producing this
hldeScence. The process they make use OF Is
SalG 10 CONSIST essentially IN submitting Jne
glass, under a considerable pressure, and at an
elevated temperature. to the action of water
containing fifteen per cent. of hydrochlorc acid.
Only certain kinds of glass are suitable for this
operation. The action of this acid is thought to
be analogous to that of the elements upon the
older glass in dSSolvtng the alkaline Silic1teS
and leaving the surface of the glass finely
| ridged or corrugated, and thus capable OF re-
fracting the lights with prtsmatic or rainbow
Colcrs, like those OF mother-ofpearl. The mod
ern glass stands any amount of rubbing or
cleaning without losing its curious property
but, il the exposed surface be cut or ground off
the 1ridescent effect is instantly lost, showing
that its cause is merely superficial and not
structural. as is the case with mother pc lr
The Bohemian glass, so far, seems to be the
favorite for embelllshing with the new rides
cence. Bohemian glass will resist a much
greater heat than any other kind. and is made
In graceful shapes, and is clear and transparent
At present the leading Bohemian factory is pro-
ducing good deal OF this irideScent glassware
principally for the European market, as the
American public is hardly yet acquainted with
this novel and beautiful glassware.
One Of the greatest charms of this new glass
Is its infinite variety and freshness. No two
pieces are alike in color, and no piece remains
the same when placed in new position or re-
garded from a different point of view. All show
greater or smaller range Of the spectrum
curve or bent. according to the shape OF the
glass; but, while some pieces flash with red and
yellow, others are tender, with a Silvery blue
or Itch gold gray, and still others exhibit all the
cClOrS or the rainbow.