Frostburg mining journal. [volume] (Frostburg, Md.) 1871-1913, 1890-03-22

last three centuries, just as painting has
done. The Venetian artists in glass have
left no successors. Beautiful effects nre
still ob:ainable in stained glass windows
and ornamental goblots, but q collection
of sixteenth century relics is not indica-
tive of modern progress, or of any COM
parison which can lie said to be other
than cd Gus.
Entering glass factory, the first object
which attracts s.tention is the great CEN
trial furnaces in which the glass is melt
cd. The most anobservant person will
have noticed tina, ordinary glass presents
itself in three aspects -brown, green. and
stainless white o. flint gla $. The former
tints are due ~ the presence of iron oxide
in the sano. which i ona of the prnci-
pal ingredients. VIII N colorless glass is
desired tine iron has to be eliminated, or
The coior masked by suitable means, and
it is n noteworthy fact that q proportion
Of iron in the sand too small to be indi-
Gated by the most delicate assay will i'm
part a distinct hue to glass. Different
metallic oxides impart different hues !;
thus tin or arsenic will render the product
white an Opaque gold will give ruby
red. copper in the form Of black oxide
with little iron ore will yield an em-
c-ald-green product; cobalt oxide blue,
manganese purple, oxide of uranium a
yellow, and SO on.
1t follows that where oolorless glass is
desired the eatest care has to be taken
to insure the use of sand in which the
metallic oxides referred to are distin-
guished by their absence.
j The furnace takes up quite large p TT
&@f tho room in glass factory, and is cir
GUAR in form, to allow the operators to
approach the pots from all sides. The
accompanying cnt will give an idea of
4 the arrangement of the melting pots or
the siege or true fooi of the furnace. As
these melting pots are of lar % size tscme
are fifty five inches in diameter) and have
TO Withstand continuously n heat which
will easily melt iron or steel, it follows
that they have to be made of we'll knea1-
el, tempered and annealed ire-elay.
There is glorious uncertainty about the
life of melting pot. 1t may give way
and break up in eight hours, or il may
last for months. In any case the sides
wear through and get thin in the lapse of
time flom the absorption of the clay
into the vitriEe molten mass within.
just so long as good pot can be patched
up and fortiie it is kept in use, but when
pot has 10 be removed, 10 matter I'M
der what circumstances, it Means
hot hard days work for all hands. The
first thing is TO dislodge the broken frag-
ments of the pot, or the whole affair
DO lily if not broken, by battering- ram
blows directed with q gigantic crowbar
in:o the interior of furnace heated like
bnto that into which Shadrach. Meshech,
and Abednego were cast in the days of
old. When the work is completed, the
new rot, already anncaled and heated to
VIII teness, has TO be placed in position,
and as the pc: and contents may weigh
many hundred pounds, the ordeal is
necessarily severe one. Burns and
blisters nre every day occurrences in a
glass factory, but the visitor soon learns
one lesson. If he wishes to old burns
and blows he will not seek 10 get out OF
the Way OF the men. lie will act most
wisely in recognizing that they have an
Independent intelligence, The man who
keeps cool in crossing street will lie