The Russellville Democrat., 1883-05-24

Those of England are highly esteemed.
Different localities OF that country afford
such as are required for every purpose.
Among these the "Newcastle' stones.
from the coal measures of Northumber-
land and the adjacent counties, have a
prominence in England for general
purposes; others are employed for
grinding, while many varieties are used
as plane surfaces for whetstoues. Other
qualities are used for homes. a German
variety Is famous for this purpose. The
very finest qualities, composed OF an
almost impalpable agglutinated power,
are used as oil stones. Such are the
water of AYR" and "blue" stones,
and the Turkey oil stone. The old
Royal Exchange OF London was paved
with this stone, and when It was burned.
about 1884. the pavement yielded a
handsome amount toward the re-
erection. The Nova Scotia and Berea
(O.) grindstones are largely employed
In this country; these may be obtained
of very large size and uniform quality.
The Washita (Ark. stone is of the very
finest quality, being sharp and clean,
and is made into a great variety of
forms-grindstones, whetstones, homes
and slips of various sizes and forms.
In dressing rough grindstoncs the pro-
cess of hacking is employed. Hacking
consists in notching the projecting parts
with a short-handled hammer resem-
bling an adj. Laps used in polishing
stones, etc., are Jared by holding an
old knife against their edges, so as to
vibrate or chatter, making slight in
dentation at each jump; these serve to
retain the finely-powdered emery or
rottenstone mixed with adhesive ma
terial, with which the lap is covered.
For clearing the surfaces of stones, in
which particles of iron or steel have
become imbcdded, square bar of one
half to one quarter inch ironis held and
wabbled against the edge while in mo-
ton. This is called Struggling or rag
ging. Turning or rowing is effected by
reversing the motion of the stone and
holding hooked flat tool against its
edge, which is afterward further
smoothed by the rowing plate. The
series of operations in making grind
stones is about as follows: The LAYER
or ledge of rock being uncovered, chan
nels are cut at each end Of the slab to
be removed. and then a row Of holes Is
drilled on the line where the fracture is
to be made. Steel wages are driven into
these holes, driving them consecutiyely
little at a time, keeping all on a strain,
until the mass cleaves from the ledge
forming large paralleiopiped. This
block is similarly divided into squares,
and these, if too thick, are split or clef,
k >1,, 81,
ness required. The square stone is now
Clipped into an octagonal shape, when
it is ready to have the eve made. This
is done by the pick-hammer. Its then
mounted on a mandrel driven at the
rate of l25 revolutions a minute. Tho
turning tools are five feet long, one and
half inches wide, and fve-eighths of
an inch thick, tapered TO point by the
blacksmith, and afterward hammered
to n hooked point by the workmen, who
turn from one hundred to two hundred
a day, according to size. An exhaust
fan withdraws the stone dust and
conductor leads it TO the outside of the
building. The stones are placed in
row, an iron rod and wooden axis
through them, wooden head at each
nuts. Stats nailed TO the wooden heads
and hoops over the stats complete the
package. The works at Berea, o., AFRO
the largest in the United States,
The large grindstones employed in
grinding gun-barrels are eight feet in
diameter, and are used until they are
reduced to a diameter Of about two feet,
when they are rejected. They are
placed in case with holes for the in
PRODUCTION OF the barrel, which Is tenn
porarily slipped upop rod. a crank 1t
one end of the latter. enabling the bar
rel to be turned while the stone Is zap
idly reyoiyed The case keeps the
water from splashing upon the work
men, and may afford some protection
against pieces when The Stone bursts, as
it sometimes viii, owing to the rapid
rate at which it is driven. The danger
of fracture can net be entirely obviated,
but may be much lcssened by elalnping
the stone ON its axis by disks instead oi
wedges Inserted hetwaen The sides of tie
eye and tho square arbor on which ii il
suspended. 1t would seem possible to
avoid the eye altogether, and depend
upon cheek-pIeces with studs or pro-
lections which penetrate into depres-
sions in the sides O. the stones. The
stones are 40 heavy that their fracture
when in rapid motion is apt to do great
damage to life, limb and property.
Artificial stones are largely employed,
especially in dry grinding and polish.
ing.
Tho corundum stone used by the Hsi-
docs and Chinese is composed of colas-
dun powdered, two parts; lac resin,
one part. The two are intimately mixed
in an earthen vessel, kneaded, flattened,
shaped and polished. 4 hole for the
axis is made by heated copper rod
The grain is more or less fine, accord
ing to the grade of the powdered
corundum. The whole is mounted
horizontally, and reyolved by q how
Ia the right hand OF the Workman, wEile
the left applies the work to the stone.
The following recipe may also be en-
ploYed: Sand OF the required lineness,
three or fo parts; sLellac, one part
melted, incorporated and nodded under
pressure.
Ransome's artificial stone, sand ag-
elomegated by silicate of lime, has been
used for grindstones with excellent
effect. In q test trial between Ran
soIne's artificial grindstones and some
Newcastle grit, TO ascertain which had
Che greatest abrasive effect, it was found
that the Ransome stone ground away
quarter Of an ounce from steel bar
three-quarter inch diameter in sixteen
minutes, while Newcastle stone (nat-