The Stourbridge Observer, Cradley Heath, Halesowen & District Chronicle.
Stourbridge, West Midlands, England, 1875-04-10 00:00:00

The Times has the following interesting particulars of M.
de la Bastie's valuable Mscovery of a process by which glass
can be toughened, and consequently very much less liable to
breakage :

Although the manufacture of glass has been carried
on for about 2,000 years, it does not appear that any
attempts to overcome its inherent brittleness and
liability to fracture' and at the same time to preserve
its transparency, have proved successful—if, indeed,
they have ever been made, which is doubtful. It is
true that the French philosopher ReSaumur .many
years since hardened glass somewhat by exposing
it to a high temperature for a considerable time.
But this process, which is technically termed de-
vitrification' while it hardens, at the same time
crystallizes the glass and renders it opaque, the pro-
duct being known as Rdaumur's porcelain. Seven
years since,- however, M. Francois de in Bastie, a
French engineer, after long and patient investiga-
tion into the subject, discovered a simple means of
rendering glass practically unbrittle, and at the
same time of preserving its transparency. There
were many delicate conditions involved in the pro-
cess by which he ,obtained this result, his success
being achieved much in the same way as was Pal-
issy's, but on endeavouring to repeat the sucaess-
ful experiment he failed signally. For two years
more M. de la Bastie, who possesses ample means,
strove without avail to rediscover the secret of his
success. At length, however, -he succeeded in so
doing, and has since been engaged in perfecting his
invention and in developing a laboratory experiment
into practical working. The process of conversion in
the main is a very simple one, so simple that it seems
singular it was never thought of before. Broadly
stated, it consists in heating the glass at a certain tem-
perature and plunging it while hot into a bath consisting
of a heated oleaginous compound. There, are, however,
many conditions in connection with the details of the
process upon which a satisfactory result depends, and
the neglect of any, even in a slight degree, constitutes
the difference between success and failure. Thus, the
glass may be underheated and will not be suscep-
tible to the effect of the bath, or it 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
constituents of the bath and their temperature have an
important bearing upon- the ultimate result. These
and numerous other points of detail have all been satis-
factorily settled by M. de la Bastie, who has designed
furnaces and baths by me ans of which his toughening
process can be 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 instantly withdrawn. The
cost of tempering, too, is stated to be very small.
We have observed that M. de la Bastie went through
a long course of experimental research before he ob-
tained success. He first worked, as an engineer natu-
rally would, upon mechanical principles. Knowing
that the fragility of glass results from the weakness of
the cohesion of its molecules, he not unreasonably ex-
pected that, by forcing those molecules more closely
together, and thus rendering the mass more compact,
the strength and solidity of the material would be in-
creased. But this doctrine, which holds good with
iron and steel, as Sir Joseph Whitworth has practi-
cally demonstrated, does not apply to glass; compres
sion failing to toughen it, even if applied to it when
in a fluid or soft condition. By applying heat, however,
which is only force in another form, the desired end
is attained, and the physical properties of the material
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 Rey and Brothers, 29, Mincing-lane,
the representatives of M. de In Bastie in England. In
these articles, which consisted of watch glasses, plates,
dishes, and sheet glass, both coloured and plain,
neither transparency nor colour is affected at all, and
the ring or sound only slightly. These articles, some
of them being exceedingly thin—were thrown indis-
criminately across a room against a wall and fell
spinning on the deal floor. Water was boiled
in a saucer over a fare and the saucer was
quickly removed to a comparatively cold place,
and was unaffected by the sudden change of
temperature. One corner of a piece of glass
was held by the hand in a gas flame until the corner
became exceedingly hot, but the heat was not com-
municatoil to the other portion of the glass neither
was it ctabliell trona' thieUteal 'A. -born6aia;
tive experiment was then made with a piece of ordinary
plate glass, and a similar piece of toughened glass in
order to show their respective powers of resistance to
fracture, from the force of impact by a falling weight.
In each case the glass was about 6in. square, and was
placed in a frame, the weight being dropped upon its
centre. With the ordinary glass, a 2oz. brass weight
falling on it from a height of 12 and 18 inches respectively
did no damage, but at 24 inches the glass was broken into
several fragments. With a thinner piece of toughened