Juniata sentinel and Republican. [volume] (Mifflintown, Juniata County, Pa.) 1873-1955, 1875-05-26
T0ughened Glass.

About seven wears since, NJ Francois
de la Bastie, French engineer, after
long and patient investigation into the
subject, discovered a simple means of
rendering glass practically unbrittle,
and at the same time of preserving its
transparency. Broadly stated, il con-
sists in heating the glass at certain
temperature and plunging while hot into
bath consisting of a heated oleaginous
compound. There are, however, many
conditions in connection with the de-
tails of the process upon which salts
factory result depends, and the neglect
of any, even in slight degree, consti-
tuteS the difference between success and
failure. Thus, the glass may be- under
heated and will not be susceptible to the
effect of the bath, or ii may be over
heated and it will then lose its shape, or
again, it may be rightly heated and yet
be spoilt in the course of transference TO
the bath. Moreover, the oleaginous con-
stituents of the bath and their tempera-
ture have an important bearing upon
the ultimate result. These and numer-
Gus other points of detail have all been
satisfactorily settled by VI. de Ia Bastie,
who has designed furnaces and baths by
means of which his tOughening process
can DE carried out practically without
fear of mischance. The time occupied
in the actual process of tempering Is
merely nominal, for directly the articles
are brought to the required temperature
they are plunged into the bath and in
stantly withdrawn. The cost of tenn
pering, too, is stated to be very small.
The physical properties of the mate
rial become altered in a very remarkable
manner. To this singular fact we can
testify, from the Inspection of "A number
of toughened glass articles at the Offices
of Messrs Abel Rev and Brothers, 20
Mincing lane, the representatives of vi.
lie Ia Bastie in England. In these arti-
cles, which consisted of watch glasses,
plates. dishes, and sheet glass, both
colOred and plain, neither transparency
nor color is affected at all, and the ring
or sound only slightly. These articles
some of them being exceedingly thin
were thrown indiscriminately across a
room against a wall and fell spinning on
the deal floor. Water was boiled in a
saucer over a fire and the saucer was
quickly removed to comparatively
cold place, and was unaffected by the
sudden change of temperature. One
corner of piece of glass was held by
the hand in a gas flame until the corner
became exceedingly hot, but the heat
was not communicated TO the other por-
ton of the glass, neither was it cracked
from unequal expansion. a compara-
tive experiment was then made with
piece of ordinary plate glass, in order to
show their respective powers OF resis-
tance to fracture from the force of I'M
pact by falling weight. In each case
the glass was about six inches square,
a Ill. Ia. I'm arh
being dropped upon its center. With
the ordinary glass, = ounce brass
weight, falling on it from height of
II inches and Is inches respectively,
did no damage, but at "a inches the
glass was broken into several fragments.
With a thinner piece of toughened glass,
no impression was made by the same
weight falling from heights ranging
from feet to 10 feet, the weight simply
rebounding from OFF the glass. An 5
ounce iror weight, tried at feet and 4
feet respectively, gave similar results
Upon the height being increased to g
feet, however, the glass broke. But
here another singular result was pro
duced: instead cf breaking into about
a dozen pieces, as did the ordinary glass
il was literally smashed to atoms. The
largest fragments measured half an inch
in length and breadth. and these were
easily reduced by the fingers to atoms
varying in size from that of a pins
point 10 that of large pins head. The
lines of fractures in the fragments pre-
scented to the eye the appearance of ir-
regular lace work. and these lines were,
moreover apparent to the touch, but
more palpably 80 on one side of the
glass than the other. Which of the two
sides was the one that received the first
impact of the blow, we were not able to
determine. Another peculiarity is that
the edges of the fractures are by no
means so sharp, and therefore capable
of causing incised wounds, as are those
of ordinary glass. Ii would seem that
the toughened glass possesses enormous
cohesive power; but that if the equili-
brium of the mass is disturbed at any
one point, the disturbance or disintegra-
tion instantly extends throughout the
whole piece, the atoms no longer pos
SeSsing the power of cohesion.
OF the practical nature of VI. de la
Bastie's unique discovery, there can be
no question whatever, nor can there be
any doubt of its value in the arts, sci
ences, and manufactures. The applica-
tions which suggest themselves are in
pnu
usefulness of the process with regard to
articles of domestic use, come impor-
tant considerations affecting the ap-
piled sciences, especially in connection |
with chemical manufactures and simi- |
lar industries, where a material, alike |
uninfluenced by the action of heat or |
acids, has been 50 long and so vainly |
sought for-notably in connection with |
vitriol chambers in the manufacture of |
sulphuric acid, and for piping in chem
ical works. For the present there re-
mains one purpose TO which toughened |
glass cannot be so easily applied, and |
that is to window glazing in odd sizes,
inasmuch A. il cannot be cut by a
diamond or other ordinary means. Our
GLACIERS will therefore have a respite,
but We cannot give them much hope
that ii will prove a long one, as eXper-
iments of considerable promise are being
conducted with the view of solving this
problem. However the glass can be cut
To the proper sizes before toughening if
desirable. The glass, however, is read
lily engraved. either by fluoric acid i'm
the usual way. or by Mr.. 1iighman's
elegant sand blast process. Ii can be
easily polished, and it can also be cut by
the wheel, As for luster work and the
like.-LoRdOR Times.
EAneaftnu