The Madisonian. [volume] (Washington City [i.e. Washington, D.C.]) 1837-1845, 1838-08-25
From the National Gassits,
COPPER FOR STEAM BoILERs.-No. z.

From rae Ndfonal Ud~eHet
COPPER FOR STEAM BoILERs.--No. z.
The tenscity Of copper at ordinary temperatures, as
demonstrated In the report 70 Congress already referred
10, 10 average Of nearly seventy experiments,
80 s26 Lbs. per square inch. The process Of rolling.
appears, gives this metal such degree Of uni
formty. that though different specimens may be found
u vary from each other much from 30 400 10 54
800 pounds 10 the square inch. nearly twelve per
cent OF tho above mean, yet in the specimen the
greatest difference In the strength at any Two points
Is not more than $40 per cent Of It's mean strength
The trials 10 prove what portion Of tho force ncces-
say TO break any bar Of copper was required 70 affect
permanently s form, resulted IN establishing about
t,oo-irds Of The breaking weight as the part IN ques-
ton
The erfsnsiSiLy Of copper is so considerable as 70
allow bar inch wide, and hreesxteen.hs OF an inch
thick to be stretched from forty forty -four per cent
Of its original length wi,hcu, breakingbut the amount
OF eongaiion depends in great on the tenn
peraiure bar broken q sli degrees was elongated
before giving way. thry-four times much - when
broken, in another part, al 9l2 degrees
The influence OF temperature copper s, TO reduce
its tenacy by every increase Of heat, that u the
strength 80 degrees Fshrenheit be known, the rise
Of temperature above that point marks very nearly the
weakening OF the copper according 70 the law that me
eube Of The elevation 81 temperature % Proportionafe 10
the square Of the reduction Of strength This gives, Ut
the temperature corresponding with atmospheres Of
pressure the safety valve Of steam engine, 1859
degrees ~ reduction Of IL 34-I00 per cent from the
strength Of copper at the freezing point. Al 5aS deg
Fahrenheit the loss is % per cent ut 65l deg %
per cent and at 1882 Ia red heat daylight) SO 10
per cent. From these data table may be calculated.
exhibiting the strength Of this metal at any temperature,
and in connexion with the table OF pressures OF steam
for the same temperatures, will enable US 70 determine
the proper thickness Of metal sustain any required
force Suppose the strength Of copper to be lbs
per square inch at 80 deg Fahrenheit ts tenacty in
pounds, for any temperature above that point, will DO
found by cnbing the namber or degrees Of Fahrenheit
ADORE hnfco, attracting the square root Of that cube
multiplying the root by The decimal fraction 703563,
and subsraeiing The product from $4,000
Extensive tables adapted 70 various pressures used
in s,esm-bolers have been calculated the basis Of
this rule which together with the demonstration OF the
law, will appear in another form They WILL il is hoped,
prove useful for those who would construct boilers
correct principles By extending the table Of the elias
tictcs Of steam at different temperatures published
few years since by the French Academicans, until we
reach pressure Of 1000 atmosphcres $4,000 pounds
on the square inch we attain temperature Of 962 deg
49, at which temperature copper would have tenacly
Of only l3,033 pounds per square inch.
The research IN question, therefore, puts us in
possession Of the of determining the exact de-
gree Of danger resulting from any known temperature
in copper boiler The formula Of the French Acade-
micians Is preferred because it is founded the most
extensive series Of observations hitherto made relative
to the elastcites Of steam at different temperatures be-
ing carried, by direct experiment to wentyiour atmos
pheres The inquiries prosecuted in this city have
tended the examinations Of the relation Of fenaciy
temperature, to much higher point the scale,
than had been done for elasticity Of steam 10 tempe
rare, by the philosophers of Paris. II will be seen,
by reference to the report, that tho tenacty Of copper
has been tried at temperature Of 1882 deg at which
the pressure OF saturated would be 1883 atmos-
pheres would require safety valve to be loaded to
the amount of 20 $50 lbs to the square inch; while
the strength Of copper at that temperature, would be
only 1926 lbs. per square inch that If boiler
tube of one inch internal diameter, made inch
thick OF "copper" (without ryets, il would scarcely suf
fee 10 bear the strain which steam generated within it
at that temperature would TO burst it, Il has
been shown that when other things equal the liza
bty Of boilers TO hurst sdrecty propoionate their
daneters; and accordingly acyindrical copper boiler
Of any Dimensions must in order to have the force Of
pressure within, in equilbro with the tenaciiies with
out at the temperature Of 1882 deg Fahrenheit have
Its interior diameter the metal must be as thick az
the diameter Of the cavity within.
Copper boilers often made OF very largo dimen-
sons, and sometimes apparently wthout proper regard
TO the pressure Il has been mentioned that those
Of the Pulaski, Of uncommon magnitude, but the
data are not at hand for judging whether viewed in
nexion with their thickness aud the pressure used
could be considered excessive. be evident that
generators. technically called that is, vessels to be
kept alta very high Temperature to receive at Intervals
portions Of water to be al flashed into highly elias
tic steam be advantageously made Of this metal
To know how much water q boiler any part Of it
when heated to high temperature expand into
steam in given time must know the weight Of me-
tai thus heated, the temperature which it is raised
its specific heat and temperature Of the water injected
This subject first examined by the writer in series
Of papers on the rapid production Of steam in contact
with metals at high temperature; !" the experiments
were commenced early in the year 1880 and the first
part Of the results appeared in the American Journal Of
Science, (vol 49,, for October, November and Decem
Der of the same year. To that and subsequent num-
beers Of the work. the reader referred for the eff
fects Of ron copper BRASS silver and gold when thus
employed red head generate steam Of atmosPhe-
rc pressure II may be added that Of copper about IL
pounds heated dull red heat will produce from boil
ing one pound Of steam and win the end Of the pro-
be found at 2l2 deg The nine required will vary
with the amount Of surface Of hot metal to which the
water has In boiler copper quarter Of an
inch thick, and presenting only face to the water,
the time will be at most minute and quarter
The conducting po,eer Of this metal greater than that
of iron. This circumstance together with the dimi-
mutton Of strength by the temperature renders the dam
ger Of allowing the water to fall below the fire level
sufficiently apparent.
From the Richmond Enquirer.