The Middleburgh post. [volume] (Middleburgh, Snyder Co., Pa.) 1883-1916, 1894-09-06
GLASS WORKING
eecuilaritics OF the Manufacture by One
who Knows HIS Business.

who Knows HIS Business.
A writer IN the Optician states
that glass is substance which, AZ
the glassblower says, has will OF its
own. II Is very often difficult to tell
how "a particular piece is going tn act
under certain conditions. even after
having tested other pieces OF the
same "batch." When subjected TO
the heat one OF "A tube will some
times respond differently from the
other end. This is in a measure due
to unequal chilling, occasioned pos.
sibly 10y sudden draught of air
while 1t in process OF manufacture.
No piece OF glass is absolutely reli-
able. Its working is, therefore, at
certain stages, most uncertain, and
one person may have entirely differ
ent experiences from another. 1t is
chameleonlike, and every process
succeeds better with those who seem
TO have a knack which Is generally
obtained by long practice.
The cutting of glass heads the list
OF the uncertain processes, for II has
no definite cleavage, and its separa-
tion is modified by the surrounding
temperature is on Hat glass In a
straight line. Here all that is neccs-
sary is a deep and regular scratch
with a glazler's diamond, firm and
speedy bend away from the main
piec- and the parts crack along the
desired line. These GLACIERS dia-
monds may be purchased and gencr.
ally prove satisfactory. but IL Is more
economical 10 purchase from some
diamond cutter Il small splinter, and
insert this INTO a piece OF brass rod
having Il small hole drilled into one
end. The splinter should now be
cemented with marine glue and the
brass rod iilcd a little upJn the side
dearest tn ru cr To obtain, after
trial. the best cutting angle for the
diamond. Another instrument for
cutting glass less expensive than the
diamond Is the glass. blowers knife,
which is a thin piece OF steel tenn
percd glass hard by heating il cherry
red anI thea plunging 1T into ice.
cold water or mercury The edge
should be sharpcned 10y rubbing IL
~ on an old, rough emery grind>tone
until Hne saw-like nOtcheS appear. 1t
is then ready for use and should. II
much used, be sharpened repeatedly.
TO cut tubes, carefully scratch at
right angles To the axis a deep notch,
either with the diamond. triangu.
tar tueA or a X ass-blowet's knife.
Heat a piece OF glass rod until a
small globule appears on the end, and
press this upon the scratch. The
glass will thus he heated more at this
Oint than at any other; an unequal
expansion takes Place, the scratch
giving direction TO the line Of frac-
ture, and the tube cracks evenly IL
It's thickness is uniform. In the case
OF Va liable thickness uneven edges
result, and these must hc tled down
70 avoid sharp cutting splinterS.
Many recipes and directions have
been given for cutting bottles Wet.
ting an asbestos string with turpen-
tine aud setting IL on hre produces
considerable heat in the glass im-
mediately underneath 1t. ByCuickly
removing the string and plunging the
bottle into cool water the UNEQUAL
strain takes place and the parts
separate. 1t is this locating or the
heat that causes the glass to crack a
we wish 1t. The easiest method. il
the means be at hand Is 10 employ
platinum wire which should lie heated
white hot by The passage OF a heavy
electric current By wrapping the
wire round "A heavy bottle or jar and
allowing the current To pass for ten
or nftecn seconds e st)utest walled
resse may be easily separated IL
touched on the heated lire with
cloth dipped in water