The sun. [volume] (New York [N.Y.]) 1833-1916, 1892-07-03
xorxs ON scrEycr AVID ryDUsrnI.

NOfhS Wv stiENCE AND INDUSTRY.
In some OF the German mines n now motbod
has been successfully introduced for prevcnt-
Ing coal dust explosions, in place OF tho usual
practice OF sprinkling water III dusty parts OF
the mine. this plan having only limited
utility. as the dust Is generated by the break
ing down OF tho coal. and explosions may arise
from the liberation OF gases at the same in
Of water has had an entirely now appli-
cation. and with a result remark ably satisisc-
q distance from each other OF about three me- a.
tres. wooden plugs are inserted. and through
them iron nipes from quarters to one me-
ire long. with openings between two and ono
hall and thrre m llimetr.,s large. and conncct-
ed with rubber hose. ltappcars that in the
to ten atmospheres and injection through two
tubes In eight hours proved sufficient to im-
and another sss "o that " Of A tho kr st
c1llicry, the water forced in under pressure
molstencd Thoroughly tho coal as far as four II:
metres above the highest hole. In carrying
out this method primary regard Is to be paid
OF tho water injected. and the ilrmness OF the
seam. the latter depending somewhat on the
Size OF tho coal pillars In tue workings.
An improved composition for printers roll
ers. as described in n London journal. con-
sists OF one round glue or gclatine. twelve
ounces water one pound and eight ounces OF
lnsced oil. from one pound to one pound and
eight ounces OF treacle or sugar. thrce.fourths
OF an ounce Of calcium. chloride. or potash.
and. II required. two ounces OF powdered
water and then melted. and the, linsecd
OIL oil, TTn nrGs, to toemncratnre OF about
very gradually, added ma thoroughly mixed
Wit, with tho melted g,u.; The sugar or treacle Is
bl" temperature. after which the calcium ehio-
ride Is Incorporated. IL very tough COM
position be desired. the rosin. dissolved by
this stage added. The composition may lie
MAJ M observation-disclosures Il water by Dispensing
similar amount Of bi-nuth carbonate.
Tho process OF manufacturing plate glass
has recently beon much sitnpl!cd. as COM
pared with the systcm commonly in vogue.
according to the claims put forth for his now
method by n Western party. 1t consists in
rolling tho sheet OF glass on perpendicular
instead of n horizontal surface; that is it ia
rolled to tho exact thickness. two sheets ut
oncc. which como out lire pire polished. rs
we'll as free from wavos. or chill. while
or marked Wilde cooling. tho operations
q grinding down and Dolls hing being thus
discussed e., with, II appears that some years
experiments for accomplishing the resul. now
realized. but failed. the surface being invari-
ably SPOILED on tho sheet leaving the machine
"a difficulty now overcome ~ a metal wheel
or mould which passes through the rollers
ana supports the glass plate. The metal sheet
is made Of high rarbon-nickel steel. aud a very
great cconomy In the production of plate glass
according to this plan is claimed.
most ingenious machine has been con.
trived for use in the operations OF wood work.
Ing. which. in the niceties OF carving
mouldngs. will execute as much in day as tho
average hand carver can produce in three
years-that is. it will produce various designs
on any kind OF wood. adapted also to run any
length width and thickness OF stock. and per-
fectly finishing from / 900 to 800 lineal feet
u material in ten hours. Its construction is
simple. so that the device requires but four
t Ry three feet q floor spaeG The die lors
mou ding is fed. like boards into planer. tho
die being Kept ut certain degree OF heat.
is made. 1t reuuires no special practice to
run the machine. the inost, important point
die being made hot by the flame from a gas
pipe; The dryer the wood the more success
ful the carving. nor does it crack or break in.
passing under the severe pressure OF the die.
but comes out as tlawless as IL done by hand.
Many ,nasterns OF dies Gan be adus ted to the
being attained with both.
Tho recent remarkable discovery by Hop.
ktnson OF the changes in tho density Of nickel
stee-contaninG 81 per cent. OF nickel--which
are produced by cooling 3O'. is another in-
stance exhibiting the alterations OF structure
produced by cold. This variety OF steel. it 10
stated. is readily magnetizable after being
frozen. though it was not before: it's den-
sity. however. Is permanently reduced by no
loss than per cent. by tho exposure to cold
startling to contemplate the effect which
would be PRODUCED by a visit to the
in temperate elm sp war ordi bSls
steel and clad with some three thousand
ing which would rpspIt from, ha zion Of
the armor by exposure to the cold would de-
stroy the shin. Experimental compound ar
cent: nickel steel. but it, remains to be seen
whethern simiar,though lessened effect would
seven por cent. o. nickel the use oil which is
warmly advocated for defensive purposes.
Some OF the most interesting information as
lately been given by Mercadier. showing that
ALLOWING iron with 25 per cent Of nickel rem
ders the metal isotropc.
The fact has been often referred to in me-
clanical operations that a smooth disk OF steel
driven at high speed will cut in two lle
hold to tho edge Of tho disk 1t is asserted.
however, that the principle here involved his
really failed OF any practical application or uso
save In one instance named by Richards n we'll
known enGinoer. who states that 1t was EN-
ployod on Il certain occasion at one of the United
StatoS armories III preparing lennon. or re-
duced section. on the ends Of tempered steel
material was hard and could not be cut. in
consequence of which resort was had to small
wheels Of iron about six inches in diameter
and one inch thick No Those wero driven at the
melting or nhrading the metal away Instantly.
at the same time drawing tho temper, SO that
n screw thread could aftcrward DO cut on the
end OF the tempered rod.
At what elevation the air Of London is purest
has been made the subject of scientific inves-
tiGation by Prim. chemical expert. the result
in question being realized. 1t appears. at about
thirty or forty feet from tho Ground-lower
than that the dust is encountered and. higher.
the smoke from the chimneys reaches. Ger
tain experiments in determining this mat
ter were resorted to-that is. frames
Of wood covered with bIsnketinG ma
tons. ono being, put on tho top OF tho
clock tower OF Westm inster. another on the
highest point OF the roof. and others at various
heights down to the, courtyard. After Ave
hours exposure In these various localities
lhero were found to be more smnts at high
the courtyard considerable quantities OF dust