The Manitowoc pilot. [volume] (Manitowoc, Wis.) 1859-1932, 1888-10-25
A BLOCK OF MARBLE.
Its Evolution from its Rough Condition
to Ornamental Use.

Few people who stand before a fin
ished monument or mantel, or even a
soda-water fount in drug store. and
admire the highly-polished variegated
marble, says the New York CONNER
cial Aduertiser, realize the amount Of
time and labor that has been expended
in the evolution of the completed
structure from the raw materials. The
highly colored varieties are found
chiefly in Italy, Spain, France, and
Belgium, or Portugal. though some
times in Mexico or Algeria. The white
stone is common in this state. Among
the marbles which most frequently
enter into composition of fancy appar-
atus are:
Italian-white, vernal and clouded,
with blush gray; Etrurian-pure por-
celain white; Saragossa-shaded cream
white. veined with dark gray; AL
gerian and Mexican onyX-trasslucent
white, veined with opaque white, yell
low or pink; Bardiglio - delicately
veined gray; Sarrancolin - shaded
pearl gray, dashed with cornelian red;
Sienna-golden yellow, clouded with
white and veined with olive and brown;
L
white; Genoa-green; Brocatel-rich-
ly notified, yellow, purple, brown,
white, and red; Violet Brocatel-pur-
pie, mottled. and veined with golden
yellow; Lisbon reddish; Gryette of
France-deep red, shaded with red and
brown; Gryotte Fleure-purplish red,
notified with pearl white; Warwick
brilliant red, veined with white; Bel
gian-velvety black; African-yellow,
white purple veins: Rouge Antique
deep red; Knoxville-grayish pink,
with light blue veining.
The colored marbles retain their
freshness longer and can be polished
after many years use.
The marble is extracted from the
quarry in oblong blocks cut by means
of wedges.
Except when designated for statuary
or building purposes, the first thing the
manufacturer does is to place the block
Of marble under a gang-saw in order
to saw it into slabs. The gang-saw
consists merely of series of parallel
saws. to which an oscillating motion
is impaired while they are kept fed
with sand and water. When they
come from the gang-saw the slabs are
generally about one and one-eighth
inches thick. so that they may dress to
one inch when rubbed on both sides.
The slabs are then inspected. To the
inexperienced eye the rough slabs are
much alike, and while the good quail
ties of the slab are only fully brought
out under the polisher's mop, the i'm
perceptible defects are also magnitied
very much. 1t is, therefore. neces-
sary to detect flaws before the polish
ing begins.
The perfect slabs are cut into re-
quired lengths by arip-saw, and passed
to the rubbing-bed to be erubbed smooth.
The rubbing-bed consists of solid
horizontal cast-iron wheel about four
inches thick, and usually about twelve
or thirteen feet in diameter. This
wheel is fixed in vertical shaft, which
rcvolves on two chilled steel friction
balls, placed one upon the other, and
incloSed in east iron box, which is
kept well supplied with oil. The box
itself is firmly imbedded in a stone
foundation, and the entire structure is
made as true and as steady as possible.
1t requires great deal of care and at
tention to keep the rubbing-bed per-
fectly true; and it is sometimes neccs-
sary to rub it down for a whole week
with bluestone in order to keep tho
surface smooth.
When the slab leaves the rubbing
bed it is comparatively smooth, and is
ready to be cut by hand into final
shape. 1t then passes into the hands
of the polisherS, who are provided with
rubbers made of ordinary ticking rolled
up into mop of about three or four
inches in diameter and sewed firmly
through and through. With these they
rub the surface of the slab back and
forth, hour after hour, until they bring
out the high polish so much admired.
The marble is first rubbed with grit,
then with pumicc stone, and then with
hone. On some white marbles oxalic
acid is then used, and finally the fin
ishing touches are given with putty of
zinc. On colored marbles emery and
French putty, prepared with sulphur
and lead. are used. 1t is estimated
that each square foot of surface pol
ished costs one man four hours of steady
work.
In gliding. four or five gold leaves
are blown into n cushion made of a
board covered with chamoiS. The
glider cuts it into strips quarter of
an inch wide, lays it on the marble
with his tip then ''cottonsn it on.
after which he rubs it down with n fine
hair brush in order to smooth the laps
and form an even and continuous sur
face. He then cleans off the edges
.,+h A. IL, 4
quired by gilders. and they seem to
handle with the greatest ease the deli
cate gold leaf which the slightest
breath of air is sufficient to carry off,
and which in inexperienced hands is
utterly unmanageable.
The variegated. dark-colored marbles
are most expensive, but they are also
generally harder and more durable, as
we'll rs more beautiful, than those that
are white or light-colored. The COM
mon white marble. which is not so
valuable from an ornamental point of
view, has separate value as being the
best basis for the production of car
bolic acid gas for the manufacture of
soda water and all other carbonate
beverages, and a large trade is done in
ii for this purpose. 1t has succeeded
whiting aud biearbonate of soda in
this respect on account of its cheap
ness. \ barrel of good marble dust,
weighing about four hundred pounds,
costs about S1.25. An equal quantity
of whiting costs about $3.50, and pro-
duces no more gas. A like weight of
bicarbonate of soda produces double
amount of gas. but costs about 81.
As far as chemical composition is
concerned, marble and whiting are
analogous II both are carbonates of
lime. and when equally pure both con-
tain the same amount of carbonic acid.
Whiting, however, is rarely. if ever, as
pure as marble. 1t consists chiefly of