The daily exchange. [volume] (Baltimore, Md.) 1858-1861, 1858-05-07
sc ENCE AND ART,


TREATMENT OF STEEL.-Al steel expands in har-
dening, but that the most which is most highly
verted, and in direct proportion to the amount of
carbon it received in that process No other gen
era rule can be given for the treating of steel for
hardening than this-that it should in all cases be
heated as regular possible to the lowest tenn
perature at which that particular kind of steel will
harden, and as little possible beyond it; for the
more highly converted the steel is, the lower the
temperature at which it will harden. The harden
ing of very bulky articles such as the face of an
anvil, cannot be effected in the way as smaller
articles by plunging them into watcr,-for the
length OF time required in cooling will be almost
certain to leave the middle of the face soft where it
is of the most consequence that it should be hard
here the anvil forge is worked by water power,
they possess the best means of hardening them; the
anvil, properly heated, should be placed in water
tank, face upwards, under shuttle connected with
the mill-dam the shuttle drawn, and heavy and
continuous stream of water let fall from height of
ten or twelve feet upon the anvil face, which cfec
tuay hardens the surface. A red hot anvil pung-
ed into water would, for time, be surrounded nv
an atmosphere of steam, which would prevent its
direct contact with the cold water, whereby its
cooling would be retarded too much to harden the
face and hence the advantage ola continuous stream
of cold water.
TESTING THE QUALITY OF STEEI.-The good ouali-
ty of steel is shown by its being homonencons bn
ing easily worked at the forge, by its hardening and
tempering well, by its resisting or overcoming
forces and by its elasticity, To ascertain the first
point, the surface should be ground and polished
on the wheel, when its luster and texture will ap
pear Inc second test requires the giving it a
heat suitable to its nature and state of conversion
The size and color of the grain are best shown by
taking bar forged into razor form HARDENING
and tempering it, and then breaking off the thin
edge IN successive bits with hammer and anvil
If 1t had been fully ignited only at the end, then,
alter the hardening, it will display on fracture
succession in the aspect of its gains from that ex-
tremlty to the other,as they are whittier and larger
at the former than the latter. The other Qualities
become manifest on filing the STEEL using it rs a
chlse for cutting iron or bending it under a heavy
weight knman long ago defined steel to be any
kind of iron which, when heated to redness, and
then plunged into cold water, becomes harder
But several kinds of cast iron are susceptibla of
such hardening. Every malleable and flexible iron,
however, which may be hardened in that wav, is a
steel. Moreover, steel may be distinguished from
pure iron by its giving a dark gray spot when a
drop of dilute nitric acid is let fall on its surface
while iron affords green one. Exposed to the air,
steel rusts less rapidly than iron.
IMPROVED LENSES AND REFLECToRs.-It is we'll
known that Button, DESTROYS of repeating the exper-
iment of Archimedes with burning glass, endcav-
ored to construct lens of water, of large diameter
Two plates OF glass nf great thickness were curved
by the neat OF concavc metallic plate, worked and
polished, and then fitted together with border of
metal, and filled with distilled water. Button thus
made lens one meter in diameter and of great
power. But he pursued it no further, on account
Y
pense of polishing the rough surface of the glass,
the material being also rendered brittle by the sec
Ond heating.
Since then there have been attempts to blow glass
lens in mould ofmcta made in halves but the result
has been imperfect, the glass uneven giving no dis
tinct focus. There has, however, been recent i'm
provement of great Importance, which consists in
using, Tor constructing the lenses, circular plate
OF grass, and section from a sphere blown with
great care-applying this to the plate and closing
them together in circle of metal and putting wa
ter between, or some other transparent liduiu 1t
forms a plano-convex lens, which may be economi-
caly made, and has nearly the purity and perlcc-
ton, without the cost, of lenses of massive lass
An improved kind of reflector is also now made,
the inventor employing sections of glass more or
less concave, cut from a sphere, and having
ON the convex part rich plating of silver from
electric deposition.
STEAM BoILERs.-A new kind of steam boiler is
announced as among the recent mechanic inven-
tons OF the day. The boiler is of cylindrical FORM
and Is terminated by hemispherIcaI, or nearly
hemspherical ends. This boiler is set in its casing
OF brick work in a vertical position and the hot air
ana the lire are made to circulate about and through
the boiler IN the following manner:-The fire is
conducted from couple OF pudding or mill fur
naccs through two ilues, and delivered near the
bottom of the boiler. After being made to circulate
about the vertical sides of the cylindrical boiler the
ilrc enters horizontal fue, passing through the
boiler at point little higher than its middle The
IRE enters the horizontal iue at both ends and pas
Scs up vertical fue chimney, which is situated
in the axis of the boiler, and opens into the horizon
tai fiue. y damper is situated at each end of the
horizontal iue, and by the hampers the drau@ht
may be regulated. That part of the vertical chm
ncy which is within the boiler is surmounted with
an AR space that is, there is anuular LAYER of air
between the chimney and the boiler, the chimney
being isolated so far its temperature is concern
ed from the upper part of the boiler. The isolatng
air space descends to Il point below the water level
OF the boiler, and any tendency which would other
wise attend the overheating of the chimney is
avoided.
NOVEL APPARATUS FOR VENTnATTNG.-A novel
and ingenious plan of securing heat in a pure state
has been patented, and consists in supplying the
apartment to be heated with an air which has been
heated by passing through a stove or apparatus
constructed as follows: An external ar-chambcr
having Its outlet opening into the apartment to be
warmed, envelopes an inner chamber or tubes in
which the gas or other heat producing combustblc
is to be burnt. The temperature of the air passing
INTO the room is raised during its circulation
through this outer ar-chamber by contact with the
heated surface of the inner chamber or tubes. The
outlet of the latter conveys the products of combus-
ton away from the apartment, so that they NAV
not vitiate its atmosphere, and air is admitted to
support combustion through valves bv which the
supply can be regulated at discretion. For venti-
latln@ apartments, the apparatus is placed in com
lnunicatlon with the yitated air occupying the up-
per part of the room on the one hand and with the
external atmosphere on the other hand by means oG
pipes. the draught caused by the heat CONVEYING
such vltiated air away. If heat and ventilation are
required conformity, the inner or combustion cham
Der only is placed in communication with the upper
part OF the room using the air thus derived for the
purpose OF supporting combustion, leaving the OK
tcrnal or air-chamber to furnish a supply of warm
air.
TRANSPARENT ENAMEL PnoroGRAPHS-A novel
and elegant adaptation of the Photographic art has
recently been brought out in London and termed
transparent enamel photographs. Transparency is
attained by fixing sheets of enamel upon glass sur
faces, the two forming one plate. Upon one enamel
face the picture is TAKEN the surface having been
rendered sensitive by the ordinary process Then,
when inverted, the glass becomes a readv-madc
protection for the pictures side and another
sheet of glass may be placed at the back or not
pleasure. The enamel surface will also take water
coors, and when thus painted, the effect is scarcely
inferior to that OF ivory. These coors are after
wards fixed by peculiar process. The advantages
thuS secured are transparency, capability of being
perfectly clcansed and, it is confidently stated
durability of coors. The purity and deicacy of the
result may be well imagined, and will doubtless
| bring the discovery into for ornamental win
dows, lamp-shades, and all other transparencies.
| On Monday last, Benjamin Ogle, convicted of man.
slaughter, at Washington, ID. c., for shooting John
webb, a lad of IL years of age, sentenced to
years Imprisonment in the penitentiary.
Hmm, 1,,n,r NJ. 1,,lI