The Rutland daily globe. [volume] (Rutland, Vt.) 1873-1877, 1875-06-07
TOUGHENED GLASS.
Great 1mportaace of the New Discovery.

The London Standard of May 16 print
the following:
nTnere are few substances which forr
SO material part of our surrounding
, as does glass. To discover method .
rendering 1t practically unbreakable "oul'
be 10 confer benefit upon huU-.hty. IN
til now all efforts in this direction have
failed. Patience and perseverance, will
however, do muc,, and a discovery has
been lately aplounced which Will revolu-
tiopize the manufacture and increase to q
fabulous extent the dses of glass. This
discovery has been made by French gen.
tleman, " Francois De la Bastie, and is
the result of years of experiment and Ia
Lor BY the kindness of Messrs. Rey, OF
Mincing lane, the agents of M. De la Bastie,
we have been enabled to inspect this inven-
ton, and to be present at the application of
tests which are absolutely decisive as TO its
success. The brttlencss q glass 10 s"u'sd
by .l aas T6iis absence s Of cobesian is s SO
great that sudden change of temperature
is sometimes sufficient to make 1t fly to
pieces, and delicate glass is shivered by the
slightest shock. 1t has long been known
that gradual process of cooling adds to
the cohesion of the particles of glass and
plate glass, and indeed all kinds of superior
glass, are cooled very gradually in what are
termed anneallng ovens. The idea occurred
to M. DE la Bastie that by some modifica.
tion OF the process far better result might
be obtained, and after many experiments
he found that a sudden plnnge into a bath
of oil when the glass was still at a cherry
heat appeared entirely to change its proper
ties. AT first he could only succeed in &C.
casional instances in rendering the glass un-
breakable, but by slow degrees and endless
experiments as to the exact degree Of heat
required he succeeded in establishing an up-
failing rule. Thus he found that were the
glass cooled in the slightest degree in its
passage from the oyen TO the oil bath, the
required effects were not obtained. In
practice, therefore, he tips the glass direct
yirom It's stand in the oyen into the bath
placed beside it. The process in no way
alters the appearance of the glass, nor de-
tracts from its clearness or TRANSPARENCY.
10 the eye the glass remains as before. but
Its properties-indeed, it may be said, its
very nature is changed. We saw watch
glasses and sheets of window glass thrown
high into air and fall upon the ground
with a crash some in falling came
half across wooden chair In
way which would have snapped the strong.
est and thickest ordinary glass had il fallen
from one-fifth of the height; we saw del
icate glass plates thrown recklessly on to
the moor. and window glass placed under
1901 and trodden upon. The glass might,
no doubt, have been broken with a ham
mer, but 1t would defy all ordinary risks of
breakage. Not only were the properties of
the glass changed, but its very nature was
as has been said, altered. 1t had ACQUIRED
so great hardness that il could no longer
be cut with diamond, 1t has lost much
of its power Of conducting heat, and when
broken by deliberate force it split up into
thousand fragments, which were so des.
titute of the ordinary sharpness of glass
that one could plunge ones hand into a
box full OF them and bring out handful |
without fear of cutting the fingers. Hence |
1t was evident that the whole molecular ar |
engagements of the particles composing it |
had been modified. This loss of conduct |
ing power and this change In fracture tes-
titled alike to the fact that the alteration |
was not mere surface change, but was
extended through the whole body of the |
glass and this was further conclusively |
proved by the fact that some plate glass.
Treated in the rough state, and afterward
ground down to little more than half its
original thickness, could not be cut with
The diamond. No change of temperature
subsequent to the alteration affects the
glass, or deprives it of its strength. We
raw an argand chimney which had been
over and over again heated almost to red
less at one end, while the temperature at
he other remained uEaltered and vat n
vas as unbreakable as at first. We saw
vater boiled in rough and very thick glass
FOWL on the fire, and then taken off and
eft to cool, and the experiment had been
epeated dozens of times without impairing
Is properties. The success of the inven-
ion is indeed complete and unquestionable.