New Orleans daily crescent. [volume] ([New Orleans, La.]) 1851-1866, 1856-05-12
valuable 1axl,erilsaents with Cast Metals.


Valuable Experiments with Cast Metals.
q finely executed ind coulprehensv work has Jus
been published by authority of the Secretary Of War
containing reports Of officers belonging to the Unite
States Ordinances Department, on the above name
RES Of years and were made to test the strength an
ether properties Of metals employed in the manufa,
lure of cannon The work is scientific one Of gres
value, especially the information il contains reatin
to the nature and atment of cast-iron material
deep interest to SO many millions OF people in our ON
and other countries. #$1 aSs4sl$ss
i The experiments were mostly conducted under Il
charge OF Major W.. Wade. who details them in a
exeeedingl clear and interesting manner. One ne
fact developed b. them is, that iron fused nu1nbt
Of times up to certain point, is thereby g1eatl
improved in strength. In trials with some iron,
4 was found that its transverse strength was nearl
doubled BY being melted and cast four times. This
discovery Of great Importance 10 all engineers aIt
i cast;iron founders AT the South Boston Foundry
experiments were made to test the strength of cast
iron, which had been submitted to fusion during on
4 terent periods Of time Eleven thousand pounds O
iron were castinto four six FOUNDER guns aItei
the metal had been under fusion Or melted ha ~
an hour; the second under fusion an hour ana
the third under fusion three hours and the fourth
under fusion three hours and three gnarters: \.
second 1T the the third was fired thirty
4 eight times, and remained u At Thus the
strength of the metal seemed to increase III the ratio
Il it was kept in the highest molten state, and it might
have been inferred from this that the fourth gun
would have been the of ALL Instead of this
being however TO be the weakest, for it
burst ut the tWenty-fth discharge In view Of these
experiments, Major Wade in this report, says these
results appear to establish satisfactorily the fact that
a prolonged exposure of liquid iron to an intense
heat, does augment its cohesive power, and this pow
Ell increases as the time Of its exposure up to some
not limit beyond which the strength
Of the iron is diminished. This is newly developed
fact in relation to cast iron subject to concussons of
deep import to all engineers. Experiments were also
made to test the transverse strength of cast iron bars
two inches square and tWenty-fonr inches long, the
metal of which was kept under fusion during differ
entperiods time These bars were set on supports
twenty inches apart and the breaking force was ap
piled atthe middle. The results obtained from four
castings were in favor Of that which was kept fused
three hours. On this head the report SAYS,
from this it appears that the cohesive power of the
ron 20 ar as It can be shownby its capacity to resist
trans is increased per cent by its con
tlnued exposure in FUSION This is also fact Of
to engineers and architects, regarding
Orders or beams; subject to a crushing force. +
In most OF the books which treat Of the strength Of
cast IRON the resistance which it opposes to certain
strains is given, but little useful information can bo
OBTAINED IN them regarding the very great difference
OF strength in different kinds OF cast iron. But as
The density between the lower and higher grades of
this metal differs as 80 to 74-a difference of 81
pounds per cubic foot, and as the tenacity Of the
metal has relationship to its density it was found by
these experiments that cast iron having density Of
$780, had only tenacity Of 1000, while that having
q density Of 400, had tenacity of As, $40.
Castings of the greatest weight according to their
size, are by far the strongest, and weighing them
is ready means Of judging comparatively Of their
strength. 5Y5 sT1I.S7%E5. - ~
the cooling of heavy castings At the Fort Pitt Iron
Works, two eight-inch and two ten-inch guns were
cast one OF each IN the common way, solid and one
OF each with core on tube of iron through which
IN nIfn 1ilnfp
from the INTERIOR according to an invention of Lieut.
Rodman The solid eghtineh gun burst at the 73d
dsehaIge the hollow cast one stood 800 discharges
and dd not burst the solid teninch cast gun stood
only twenty tires while the hollow teninch gun stood
40 These guns were cast Of the same material and
at the same times the difference in favor Of the hollow
cast guns is astonishing. This is attributed to the
method q cooling it being supposed that in cooling
that strain is exerted upon the arrangement Of the
particles OF the metal in the same direction as the
strain Of the discharges. =
Lieut.. Rodnan goes into very subtle mathenlat-
zeal demonstration to show that this is the case ana
that his method of cooling the casting obyates this
unequal strain But on the back of this Major Wade
presents new fact in relation to the effect of fine
liter the made and before they are used
which is also OF vast Importance to engineers Eight
neh guns proved thirty days after being cast solid
TODD but ~ charges; gun of the same BORE proved
hrty-tour days after being cast, stood 81 charges
Vhlle one which was proved 100 days after being
as' seooc tol chafges ana another proved after be-
ng cast six years, stood 592 charges. What an i'm
orant fact is thus newly developed showing us that
old cast cannon should not be actively used until
hey have been kept for some years. Major Wade ac-
cunts for phenomenon in cast iron by supposing
hat the particles strained in the cooling re-adjust
themselves in the course of time to their new posi-
ION, and become free or nearly So and he presents
'ome good arguments i'll favor OF his theory.
The lesson to be derived from this by our engineers
$ that heaVF castings OF iron for beams and machi-
lery subject to strains less capable of resisting
hem Immediately after being cast. In other words,
I'D castings are much stronger than new iron cast
ngs. INK
There is much other new and useful information in
this work. to which we cannot find room to allude in
s article but will take occasion to do SO in future
one TScientifc American