The Cincinnati daily star. [volume] ([Cincinnati, Ohio]) 1875-1880, 1878-05-23
SCIENTIFIC

| ing tne maximum limit 70 the size OF a
blast furnace to be that at which the tenn
perature of the waste gas evolved from
the furnace top will have become cooled
down to the temperature of the external
atmosphere by its passage through the
materials, it would not be beneficial to en-
ploy greater capacity of furnace than two
and-a-half times that of the largest Cleve-
land furnaces of 20, 900 cubic feet, suppos-
ing the ore to contain forty per cent. of
iron, and the blast to be delivered at 900
degrees. This conclusion, however, must
manifestly be affected by the rapidity with
which the heat escapes through the sides
of the furnaces, and, in the case of fame
jacket, it would not apply.
THE residum oil obtained by distilling
petroleum isnow eficaciously employed in
currying and dressing leather. When the
residum oil is of specific gravity of about
$50. it is used with tallow in the proportion
of fourteen pounds of oil to sixteen pounds
of tallow. BY thus using such oil for this
| purpose, it SO combines with the tallow as
to carry it almost wholly into the skin, and
80 gives it good stufing, imparting also
greater elasticity and more permanent
weight to the skin than other oils, besides
rendering the leather more impervious to
water and less liable to decay or gum. A
mixture, consisting of fourteen parts of
the residum oil TO sixteen parts of tallow,
with two to three parts of cod oil added,
to make the compound more fluid and thus
work easier, is found well adapted for
dressing leather, though in cold weathe,
less talow isrequired.
PROF. SoRBY concludes as the combined
result of observation and theory-that the
normal limit of distinct visibility with the
most perfect microscope is one-haIf of the
wave-length of the light; and, this being
the case, even with the very best lenses,
except under special conditions, light it.
self is of too coarse a nature to enable us
to define objects less than 1-S0, 600 to
LOO, 900 of an inch apart. 1t would ap-
ton is concerned, microscopes have already
reached their ultimate limit. 1t is calcu-
Lated that in the smallest interval which
could be distinctly seen by the best possible
microscope, there would be about 2,00O
molecules of liquid water lying end to end
or about 520 of albumen, and that. in
order to see the ultimate constitution of
organic bodies, a magnifying power from
800 to 1000 times greater than that now
possessed would absolutely be required,
and of this there seems to be no hope.
AN efficient piece of mechanism recently
constructed in England, is machine
adapted especially for bending angle irons
for the rings of boilers eight feet diane
ter, and consists of large circular cast
iron table, to one side of which the bond
ing device is attached. There are one
large and three small vertical rolls, the
larger one revolving upon fixed spindle,
while the spindles of the others can be
trayersod by means of screws. The angle
iron to be bent is gripped between the
fixed and the middle trayersing rolls, and
the two outer ones are then moved forward
simultaneously to bend the bar to the
curves required. One of the large hand
wheels is used for moving the gripping
roller, and the other for traver8ing the
bending rolls, the screws employed for
this being geared together. In the driy-
ing OF the gripping rolls the moving roll
is connected to the gearing by univ ersal
clutches, which allow q free motion to be
given to tho aiding bearing. The two
bending rolls are of course free On the
spindles, and are not driven For carry
ing the angle irons upon the table, rollers
may be recessed into it's face.
The daily consumption of lucfcr matches
In France is estimated at the rate of half g
dozen per head of the population; the pro-
portion for England is as high as eight
and it reaches nine for Belgium. Basing
the estimate upon that of six per head per
diem, the daily consumption of these use
full little articles throughout the whole of
Europe is set down at over two Thousand
million. The weight of these matches va
ries considerably, those most in use in
France giving about 1,340 to the pound
while the same weight will yield three
times as many of the round and square
description common in other countries.
Assuming, however, LOO as the average
the daily quantity of wood consumed in
their manufacture would amount to some
800 tons. Poplar and aspen are generally
preferred for this purpose. The weight of
the former, per cube foot, when squared
and reduced to available dimensions, is
about twenty pounds. Making all allow
ances for loss by saving and other causes,
that arise before the wood becomes con-
verted into marketable article, it is found
that out Of a. cubic foot. of rough unhewn
tim har pnt