Sacramento daily record-union. [volume] (Sacramento [Calif.]) 1875-1891, 1884-11-08
Iempered Glass.

1t is not very long, says the Glassware
Reporter, since the discovery of NJ. Alfred
de la Bastie filed all our newspapers with
paragraphs, more or less ridiculous, about
the properties of the glass Some claimed
1t was malleable; others that it could not
| be broken. In fact, tempered glass was
called upon to supersede all other ma
! terials. The excitement being over, tenn
pered glass may now take its rank among
valuable inventions, subject, however, to
many defects in its present state The
process OF tempering glass, as is we'll
known, consists in heating piece of glass
say a window pane, to such a degree as to
to lose its shape; the glass in this state is
instantly plunged into bath composed of
fatty and resinous matter, which is heated
and maintained liquid at a temperature
ranging from 5000 to 6000, according to the
quality of the glass. The difference of
temperature between malleable state, about
1902, and that of the bath constitutes the
temper Until the discovery of tempered
glass by NJ. de la Bastie it had always
been considered that, unless a lamp Chin
ney Or any other piece of glass was
perfectly annealed, differences of tenn
perature brought on suddenly would
invariably cause 4 breakage. The
Bastie glass would seem to prove this view
TO be erroneous, rs the tempered glass can
sustain sudden and extreme changes of
temperature without breaking. Molten
lead has been poured into glass bowl Or
tumbler without producing a fracture. 4
piece of plate glass tempered by the Bastie
process, having been heated among Goals,
was suddenly plunged into cold water
without producing any effect. This expert
ment, repeated FIVE times in succession, did
not seem to impair the qualities of the
glass, for on dropping it from tifth-story
window it did not break. 1t may be said,
however that if in the heating the tenn
perature should reach the point at which
it would be annealcd, the temper would be
destroyed This action does not seem to
take place when the period of heating is
not continued too long. A plate Of glass
64x42 inches and 3-16 inch thick could
only be broken under the shock Of weight
of seven ounces falling thirteen feet, while
an ordinary piece OF glass of the same di-
mansions would break under half of that
weight falling about sixteen inches. NJ.
Siemens, Of Dresden says that the strength
of glass is increased fifty times by being
tempered. 4 bent plate of glass laid upon
the floor with the convex side upward is ca
pable of resisting the weight Of an ordinary
sized man without breaking. Theglass while
subjected to the weight will ilatten out,
but as soon as the pressure is removed it
will spring back at once to its original
shape. Hardened glass seems to be less
dense than the ordinary glass; it is harder,
however, and is more difficult to cut by
the diamond and tempered tools; it also
possesses a much superior elasticity over
the ordinary glass. Since tempered glass,
however, cannot be cut with the diamond
without flying to pieces, it's use must nee
essarily be limited to definite sizes not re-
quiring to be modified; this is quite a
drawback to its USE 1t would seem, how
ever, that some of the defects have already
been overcome, for at the Paris Exposition
quite display of tempered goods was
made by the ''Societe Anonyme du Nerre
Trempe" of Paris. Among other things
was quite display of druggists and chem
zeal glassware, mortars, pestles, beakers,
covered bowls, tunnels; also variety of
plain and cut-glass tumblers, goblets, de-
canters, globes and chimneys, opal plates,
depolished bowl with cut facets, colored
glass, engraved, cut, etc It is said that
the making of articles varying in thick
ness is hazardous as many of them are
apt to fly to pieces either in the making
or cutting.