Burlington weekly free press. [volume] (Burlington, Vt.) 1866-1928, 1875-06-25

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seutiie he fell upon her, and landed on the
knife. So closed his strange career, and his
wife is on trial for murder.
Toughened Glass.
An ACCOUNT OF THE REMARKABLE Ia BAsTIE
PROCESS, BT PROF. THOMAS FcLksroS-Ex-
PERMESTs BY THE LECTURER.
Prot Thomas Egleston, of the Columbia
College School of Mines, presented last
evening, an account of the remarkable La
nis1le process Tor toughening glass, Sd as to
render II incapable Of breaking, before the
Ne"-1 ork Academy of Sciences The no.
!i .ices oi the process which have appeared from
time to time have inspired considerable in
'erest IN the matter, and large audience
was expected. but only few were present.
froi. Egleston said that he had brought
number OF specimens Of the hardened glass
10 exhibit, but that he must request that the
| specimens thrown on the floor might be re-
turned; lie said that, during last Autumn,
NJ La BastIe, having made a number of ex-
periments IN making glass, (being connected
WIN glass manufacturing succeeded in max
ing 1t as tough as cast iron. He does this
oy heating ordinary glass to a red heat and
plunging into bath of fatty material. the
composition of which he has not disclosed
Prot. EglestOn then threw number of
specimens OF the tempered glass, several be
ing watch crystals, and equally thin pieces.
IN the air. They fell on the floor with a me
tallle clang, and rebounded TO the height of
several inches Some Of these pieces were or
binary looking watch crystals After showing
the strength Of the specimens in this way.
Prof. Egleston threw plate in the air, and af-
Ter several attempts succeeded in breaking il.
de then detailed large number of expert
ments which had been made bv him on the
| glass with reference to its capacity for with
standing shock, its resistance of heat. and
It's chemical strength ascompared with ordi-
nary glass. With regard 10 shock. he said
he had 4 number of steel missiles made. of
two, four, SIX, eight, and sixteen ounces
weight, which were allowed to fall from diff
lerent heights on the plates OF prepared glass
lie had done tins because he found that none
oil the shocks usually applied TO test glass
would break this The missiles were care
iully prepared, 50 that their edges would
not be dented, thus preventing the waste of
any Of the force Of the collision on the mis-
sile itself. From nearly 100 experiments
he t0und that ordinary one and a-quarter
inch glass always broke under blow from
a missile falling thirteen inches, while the
tempered never broke under a fall of les
than five feet. \ two ounce missile was
dropped from different heights, increasing
by three inches up to thirteen feet, and the
prepared glass withstood these shocks
A test was then applied of suspending
weights. A piece Of ordinary glass 81
inches wide, and 27-l0O inch thick
| generally broke under weight of
fifteen or sixteen pounds, although one
/ piece stood a weight Of thirty-seyen pounds,
while similar piece OF the prepared glass
stood over 100 pounds without breaking.
A long series Of experiments was then made
in glass made for vault lights, and the tenn
! pered glass a quarter Of an inch thick was
found 10 be superior to piece Of ordinary
commercial glass an inch and half thick
FIRST the weights were 50 applied as to bring
the test Oh a knife-blade balance or a mathe-
matical line \ piece Of ordinary glass
broke under fity-iour pounds, while a simi-
lar piece Of the tempered only broke az
| pressure Of l55 pounds When the weight
was distributed over a width Of 10 OF
three inches ordinary glass broke at from
| fifty to sixty pounds, while the TEN pered
stood test OF 2l0 pounds and, in one in
stance, the weight was piled on until the
support Of the platform OIL which the expert
ment was being conducted gave way, and
the platform broke down, while the glass
remained unbroken
The strength OF the glass was not, how
| ever, its most wonderful Characteristic Its
resistance TO heat wasialso marvellous. The
temperature Of different ordinary flames was
| first determined by means Of promoters
constructed for the purpose, and was found
10 be from 300 : TO 1000 according to
the kind Of fame Two thousand degrees Of
heat was then directed on the centre ola
| plate of prepared glass, eighteen inches
| square, until at the point Of contact with the
| fame the glass became red hot The hand
could not then be borne within three inches
Of the red hot portion of the glass. vet the
glass could be comfortably handled if grasp
ed four inches from the red hot part The
first plate was poor one, and broke after
being subjected to this heat tor three min
utes. The others were not broken bY it,
1t was found that the glass could be safely
cooled 100 at time, but cooling it more
rapidly broke it. Ordinary glass stood such
tests as these only eight seconds. The ap-
| plicatiOn Of this was that if a fire was start
ed in a room with windows Of this glass. the
framework of the windows would burn out
and allow the glass TO fall before draft
would be created. Lamp-shades were then
tested by using kerosene lamps with com
binatlon Of Bunsen burners, which threw a
blue flame, (shCwing that the carbon was all
consumed, making the heat intense,) along
the whole length Of the tube and six or
eight inches beyond it. All kinds Of lamp
chimneys known had been tried bv this test.
and none were found that could withstand
it. The tempered chimneys were the sub
mitted to the test for half an hour and then
cooled and again tried for half an hour
The consequence was that the lime glass was
somewhat discolored but not craked The
lead glass was blackened but not broken.
and when cooled, was thrown about the
floor without injury. Photographs had been
taken on this glass, and the glass found to
be unaffected. The glass had also been
polished like plate glass. This had been
found to be difficult owing to its elasticity,
but the prepared glass takes more brilliant
polish than the ordinary, and does not lose
its strength. Etchiugs were made on speci-
mems of the glass, and the finest designs
were reproduced by means of the sand blast,
without injury to the strength Of the ma
terial. Other tests were applied. Water
was boiled in vessel of this glass The
wate- boiled out and the vessel remained
uninjured. The temperature Of the vessel
was then raised to $50 : and cold water was
poured in with the expectation that II would
crack the glass. But the water began i'm
inediately 10 boil, and the glass was unhurt.
The temperature was then raised to 30j :
and cold water cracked it This was hard
" to be wondered at, as a brass or copper
vessel submitted to the same test would be
damaged
"These, said the lecturer ARE the tests.
This glass is. to my mind the best non-con-
ductor of heat there is Among the uses
proposed for it are carriage lights and head
lights for locomotives. One enthusiast had
even proposed to make wagon wheels of It. "
In reply to questions By members of the
academy, Prof Egleston then said that the
optical properties of the glass had been
studied, but not satisfactorily, as the glass
now made was of poor texture tor that pur-
nose. NJ. La Bastie having thus far only been
able to supply the demand for specimens
needed for experiments. Several persons
had stolen specimens, and had afterwards
preferred the claim that they had hardened
the glass themselves, but the imposture had
been discovered. One man, however, had
come to the speaker. who presented mum
Der of specimens Of poor 9 ass similarly
tempered. and had made the same claim, and
the Professor said he WIS satisfied his o.
truthfulness.