The morning call., 1894-07-11
NEW WESTFRN VOTEL.
GLASS HAS A WILL.
SO Says One Who Is Engaged in
the Manufacture OF Ii.

the Manufacture OF 1t.
Glass is a substance which, as the glass
blower says. has a Will of its own. II is very
often difficult to tell how a particular piece is
going to act under certain conditions, even
after having tested other pieces of the same
batch" When subjected 10 the heat one end
of a tube VIII sometimes respond differently
from The other end. This is in a measure due
to unequal chilling, occasioned possibly by
sudden draft OF air while II is in process OF
manufacture. No piece of glass Is absolutely
reliable. Its working Is therefore al certain
stages most uncertain, aud one person may
have entirely different eXl eIlences from an
other. IL is chameleOnlike, and every process
succeeds better with those who seem to nave
knack, which Is generally obtained by long
practice.
The cutting of glass heads the list of the I'M
certain processes, for IT has no definite cleavage
and It's separation is modlhed by the surround
ing temperature. The simplest separation is
Oh fiat glass in a straight line. Here all that is
necessary is a deep and regular scratch with
GLACIERS diamond, firm and steady bend away
rom the main piece, and Tie parts crack along
the desired line. Ibesr glaciers diamonds may
b. purchased aud generally prove satisfactory,
but it is more economical TO purchase from some
diamond cutter small splinter and insert this
a piece of brass rod having small hole drilled
into one end. The splinter should now be
cemented with marine glue, and the brass rod
filed a little upon thu side nearest he ruler, 10
obtain, afrer Il Trial, tue best cutting angle for
glass less expensive than the diamond Is The
glass blowers knife. which Is piece OF thin
steel tempered gasshafd by heating lt cherry
red, and then plunging IL into ice cold water or
mercury. The edge should b. sharpened by
rubbing ii upon an old, rough emery grind
stone until fine saW-like notehes appear. Is
then ready for use and should, II much used
be sharpened repeatedly.
To cut tubes. carefully scratch ar right
angles TO the axis a deep notch, either with the
diamond, triangular file, or a glass blowers
knife. Heat piece Of glass rou until small
globule appears on the end, and press this upon
the scratch. The glass will thus De heated
more at this point than at any other; an I'M
equal expansion takes place, the scratch CIV
ing dill ectlOn to The line OF fracture, and the
lube cracks evenly. II its thickness is uniform.
In the case OF variable thickness uneven edges
result, ana these must be filed down 10 avoid
the sharp cutting splinters Many recipes and
directions have been given for cutting bot
ties.
Wettng an asbestos string with turpenline
and setting it on FIRE produces considerable
heat In the glass Immediately underneath il.
BY quickly removing the string and plunging
The bottle INTO cool wa er the unequal strain
taNe s place and the parts separate. Ii is THIS
locating Of The heat that causes the glass TO
crack as we wish it, The easiest method, if The
means De at hand, is 10 employ a platinum
wire, which should b. heated white hot BY the
passage Of heavy elec rio current By wrap
ping this wire round a heavy bottle or lar and
allowing the current'tO pass for ten OF fifteen
seconds the stouIest walled vessel may be
easily separated II touched on the heated line
with cloth dipped in waIer.-Optician.