South Branch intelligencer. [volume] (Romney, Va. [W. Va.]) 1830-1896, 1875-07-16
Recent improvements in Glass
Manufacture.

The recent discoveries and inventions
OF Nj: De la Bastie, in France, in anneal.
ing glass, the improvements on his pro.
cess by MIR. Charles Pieper, of Germa.
ny, and the method of hardening glass
by Mr.: Macintosh. of England, show
that, whatever we may know about the
chemical constituents of different varie-
ties OF glass, its physical properties are
still almost terra ircoyaita
| We have been so accustomed to con.
slider fragility as unavoidably connected
with the conception Of any glass object.
that the idea of glass bottle or goblet
which may be knocked about and thrown
on the floor, or of glass pane which
will not break when stone is flung a.
gainst it, appears an impossibility, if not
an absurdity.
AT the same time, all well informed
persons know that the value Of precious
gems consists i'm their hardness, which
enables them to keep their polish, while
all glass limitations tarnisb soon, that
the test wherewith to distinguish gem
from glass imitation is the application
OF the corner OF steel file, which will
scratch glass but not real gem If now
MIR. Macintosh finds way to make glass
as hard as n diamond, so that powder
obtained from such glass can be used in
place OF diamond dust, what will become
Of all the comparative degrees of the
value Of gems? If paste Ia soft lead
glass imitation of diamond. which very
nearly equals the diamond in luster) can
be made rs hard and rs lasting rs the
genuine gem, what is the difference to
the wearer, except that he knows that
his ornament cost only So or $40 in
stead of $1,000 or $4,000? We have
heard the most eminent jewellers of New
York city declare that paste limitations
are often so fine that, when worn in the
evening, it is impossible to distinguish
them from the real article. He confessed
that he was unable TO decide rs to their
genuineness unless he were allowed to
have the articles in his hands under
daylight illumination.
Glass appears, then. to have proper
ties similar to those of steel which re-
late to hardening and annealing. We
may change the temper of steel tool
10y heating and slowly cooling. and this
is what is done with glass by DE la Bas.
tie and Pieper, by the Intervention of n
proper bath, the chemical nature Of
which undoubtedly plays an important
part. On the other hand, we may make
steel hard by suddenly cooling it when
very hot, and we may modify the nature
OF the steel by exposing it to the action
or diverse substances, among which
carbon is the most important, the influ-
ence of the carbon being very powerful
rs the addition or abstraction of one
halt to one fourth per cent: of carbon, to
or from the steel, results i'm great diff
ference in its physical qualities. 1t is
so with glass. Mr.. Macintosh, after
having pressed the heated glass to the
proper shape in iron molds according to
the usual method, transfers it to thin
platinum molds, brings it nearly to the
fusing point, and then suddenly plunges
1t into freezing mixture containing
snow, ice water, and salt. or their equiv
alents, or in some other mixture produ-
cling an intense cold, different kinds of
glass requiring different mixtures. This
latter point is now under investigation,
and the results promise to teach us a
great deal more about the most remar-
kable and useful material, without which.
as Liebig remarked, our progress in
Science could only have been very iimi-
ted. 1t is hardly necessary to enumer-
ate our obligations to glass. Without
it no telescope nor miscroscope. no ba-
rometer, could have been invented and
no modern astronomy, hardly any che
mistry, and hut little physical science
would have been possible.-Scientifc
american.