Sunbury American. [volume] (Sunbury, Pa.) 1848-1879, 1856-06-07
arr ENeTH OF CAST lRoN.

~ the ValuaOle report OF tne- e8perlmenIs
made on this subject by the ordnance depart
Secretary Of War, and which the editor Of
the American Mining Chronicle has ntten-
lively reviewed, there is much that is worthy
OF notice and likely to prove very useful with
reference to this only partially understood
branch of the iron business.
The experiments we're mostly conducted
under the charge Of Major w. Wade, who
details them in an exceedingly clear and in.
terestng manner. One new fact developed
by them is. that iron fused number Of times
up 20 certain point, is thereby greatly ir-
proved IN strength In trials with some iron
it WAS found that its traverse strength was
nearly doubled by being melted and cast four
times. This is a discovery of great imror-
tance 10 all engineers aud st-ron founders.
AT the South Boston Foundry, experiments
were made 10 test the strength of cast-iron
which had been submitted to fusion during
different periods Of time. Eleven thousand
! pounds of iron were cast into four six-poun-
der guns; one after the metal had been un.
! der fusion ar melted half an hour; the second
HDder fusion an hour and half; the third,
! under fusion three hours three quarters
| The gun first cast burst at the thirty-frst fire;
! the second, at the thirty-fourth; the third fir
ed ,hir,y..ight times, and remained unbroken.
| Thus the strength Of the metal seemed to
| increase in ratio corresponding to the period
| Of fusion, or under which it was kept in u
highly molten state. and il might have been
| inferred from this that the fourth gun would
have been the strongest Of all. Instead Of
this being SO, however, il proved 10 be the
weakest, for it burst ut the twenty-flth dis
charge. In view Of these experiments. Ma
jur Wade, in his report, says: these results
appear to establish satisfactorily the fact that
tense heat, does augment its cohesive power,
and this power increases ut the time Of the
exposure up 10 some mot we'll asccrtained)
Limit. beyond which The strength cf Inc iron
| is diminished. This il new developed fact
in relation To cast iron. snhie to conclusions,
OF deep import 30 all engineers. Expert
Hrn's wer. also made to test the transverse
! strength of cast iron bars, two inches square
aud tNrnty.foGr inches long. the metal of
which was kept under fusion during different
periods O. time. These bars were set on sup
ports tweuty inches apart and the breaking
force was applied at the middle. The results
Obtained from four castings were in favor Of
that which was kept fused longes;--three
hours On this head the report says: from
this It appears that the cohesive power Of the
iron. so far rs it can bc shown by its capacity
to resist transverse strains, isincreased 60 per
cent by it's continued exposure in fusiun.-
This is also a saci Of Importance 20 engineers
and architects, regarding girGers anu beams.
subject 10 II crushing force.
In most Of the books which treat OF the
strength OF cast iron, the resistance which IL
opposes to certain strains is given; but little
useful information can be obtained in theui.
regarding the very great difference ofstreuglli
in din;.r,ut kinds If east iron. But IA the
density between the lover and the higher
grades of this metal differs as CO to T.3--u
difference of thirty. one pounds per cubic foot
and as the tenucity OF the metal has reia
tionship TO its density, it was found by thes,
experiments TINT cast irou, having densi!
of $500, had only n tenacl,v of 5000: Will,
that having density of 1000, had tenaci
ty Of $3.50.
Castings Of the g4eatest weight, according
10 their size are uy lar me s'roheost, aho
weighing them is n ready means o! lutSihg
comparatively OF their strength.
some important incls were also developed
IN Relation to the cooling oi heavy Castings
Al the Fort Pit l'oE Works. two elght aho
two ten inch guns wcr" cast, one OF ehch III
the common way solid aud one OF each with
core or tub" nj iron. through which water
was mad" To circulate alter Casting 10 coo' II
RON tie lntor or according to an invention o
LIEUT.. R"tman. h" soii" eight men guU
h"rSl NJ me ga nsThaFgt; 'ne h"i'"% cas-
one s'Uro l'""o "lsc""rseS' an" ,'!o n". o"'s.
s"' s"'iu zen ihSh r"S' gun e'"'u "n'l '"cn,
~ nr's' ""''e 'he Ho''"" ch i"'" E"n s'o"" -
NJ" guns were c"S' I'll 'hr s""c '"'
"GH ut t'm same 'ime ihe "l'et'Ne III 'nsol n,,''
iug supposed that in cooling the s,ili guns