Alexandria gazette. [volume] (Alexandria, D.C.) 1834-1974, 1875-04-30
TOUG II b n K D u l. Il S 5.
From the London Times.


Although the manufacture of glass has been
carried on for about two Thousand years, 1t does
not appear that any attempts to overcome lts
inherent brittlencss ani liability to fracture, aud
at the same time 10 preserve its transparency,
have proved successul-it, indeed, they have
ever been made. which is doubtful. 1t is true
thai the French philosopher, Reaumur, mauy
wears since hardened glass somewhat b3 expos
iug tito a high temperature tor considerable
time, But this process, which is echncally
termed identification, while 1t hardeDs, at the
same time crystalIzes the glass aud renders 1t
ouauue, the prouuct being known as Reaumur 8
porcelaln, Seven years suce, however, VI.
Francois de Ia Bastie French engineer, after
long ard patient investigation into the subject,
d,,coyereu simple means OF rendering glass
practically uubrittlc, aud at the samc time of
preserving it's Transparency There were many
delicate conditions involved in the process by
which he obtained this result, his success being
achieved much in the same way as Pali>sys,
but on endeavorlug TO repeat the successful ex-
pertinent he failed signally. For two years
more NJ de la BaStie, who possesses ample
means, strove without avail to redlscover the
secret of his success At length, however, be
succeeded in 50 doing and has Sioce been en-
yaped in pertecting his invention, aud develop
iug laboratory experiment into practical work
ing. The process of conversion 10 the main Is
a very simple one, so simple that 1t seems
singular it was never thought of before. Broad
" stated, it consists in heating the glass TO
certain temperature and pluugirg it while hot
into bath consisting of heated oiraglnous
compound There are, however, many con
dtiops in connection with the details of the
nrocess upon which satisfactory result
depends, and the neglect OF any, even III a
fhn Ittt hp-
tween success and failure Thus the glass may
be under heated, aud may not be susceptible
to the effect Of the bath, or it may be over
heated aud then it will lose its shape; or, again,
it NAV be rightly heated, and yet be spoiled 10
the course OF transtereDce to the bath. More
over. the oleaginous constituents OF the bath
and their temperature have an i'm portant bear
ing upon the ultimate result. These and nu-
merous other points OF detail have all been sat
isfactorily settled by Nj. de la Bastie, who has
designed furnaces and baths by means of which
his toughenlug process can be carried out prac-
tically without fear of miSchaDce. The time oc-
cupicd in the actual process Of temperng is
merely nominal, for directly the articles are
brought 10 the required Temperature they are
nluuped toto the bath aud instantly withdrawn.
The cost Of tempering, too, is stated 10 be very
small.
We have observed that NJ de la Bastie went
through long course OF experimental research
before he attained success He first worked,
as an engineer naturally would, upon mechani-
cal principles. Knowing that the fragiity OF
glass results from the weakness of the cohesion
OF its molecules, he not uureasonaby expected
that, by forcing these molecules more closely
together, and thus rendering the mass more
compact, the strength and solidity of the ma
tolal would be Increased. But this doctrine,
L. - Il l., nr,I W
Joseph Whitworth has practically deDonstrat-
ed, does not apply to glass compression fail
Ing to tougher it, even if applied to II
when 10 fluid or soft condition. BY ap
plying heat, however, which IS only force 10
another iorm, the desired end is attained, and
the physical properties of the material become
altered iu very remarkable manner. lu these
articles, which consisted OF watch K asses, plates,
dishes and sheet glass, both ceored a1d plain,
neither transparency nor color Is affected at all,
and the ring or sound only slightly. These ar
tlce>--some Of them being exceedingly thin
We're thrown indiScrininaely across room
against wall, and fell spinning on the deal
floor. Water was boiled in saucer over tre
aud the saucer was quickly removed to com-
laratlvely cold place, and was unaffected by
The sudden change OF temperature. One cor
ncr OF piece of glass was held by the hand III
ras Hamc until the corner became exceeding
y hot, but the heat was not communicated To
the other porioo Of the glass, neither was 1t
cracked from uucqual expansion. A compare.
tive experiment vas then made with piece
Of ordinary plate glass and similar piece OF
icushened glass in order to show their re-
:letvc powers of resistance to fracture from
the force of lmpact By a falling weight ln
each case the glass was about SIX inches square,
aud was placed in frame, the weight being
dropped upon its centre. With the ordinary
glass, a two ounce brass weight falling on 1t
iTom height OF II and Is inches respectively
d'd no damage, but at "A ,uches the glass was
broken into several fragments. With thinner
piece of toughened glass ou impression was
uaie by the same weight from heights
ranging from to 10 feet, the weight simply
rcbouudng from off the glass An eight
ounce iron weight, tried at aod feet
respectively, gave similar results. Upon the
hclSht being increased 70 six feet, however,
The glass broke But here another singular
feSui, was produced; instead Of breaking into
about 4. Zen pieces, as did the ordinary glass,
Il was literally smashed to atoms. The largest
rasmcuts measured about half an luch 10
Fnsth aud breadth, and tkcSe we're easily re-
auced BY the fugers to atoms varying IN SIZE
!t0m that of pins point to that OF large
l'h head The liues Of fractures in the trag-
4ents presented to the eye the apr earance OF
irregular lace work, aId these lines were, more
V'eF' apparent to the touch, but more palpably
"9 "G one side Of the glass than the other. Which
VI % tie two sides was the one that received the
u'S impact of the blow We are not able to de-
oI'Ine ~Irn'ne. Another pecuiarity is that the edges
VI " Tue fracture are by no means SO sharp, and
.uefeiore capable of causing lnciscd wounds, as
,ts .ts those of ordinary glass. 1t would seem
.'a snat the toughened glass possesses euormo Gus
,Hb"eSlVe ,bDSlVe power, but that if the equilibrium of
,ns, uaSS Is disturbed at any one point the dis
II,oa0ce I,0c;e or disintegraton Instantly extends
r'Oughout hwy the whole piece, the atoms no
,b"sef possessing the power of cohesion. Of
d;S,p d. pracucal nature of NJ de la Bastie's unique
pos povsosery there can bo no question whatever,
arr eau M there be any doubt of its value 10 the