The news and herald. (Winnsboro, S.C.) 1877-1900, 1880-12-18
History Of Firc-Proof safes.


In regard to the invention or flrc.proof
safes In America, the accounts we have are
conflicting. 1t Is said that somethip&over
fifty years ago the discovery was made by
mechanic who attempted 10 boil Water IN
kettlethat was covered with plaster Of paris.
he found that it was almost impossible to
heat the water to 3 boiling point, and CON
cluded that plaster Of paris, therefofa was
great non conductor OF heat. Ihfelating
his experience to several there probably
was among them some one who conceived
the idea Of applying it to fre-proof safes.
After this discovery little, If anything, was
used In this country for filling safes, but
plaster for about twenty five or thirty Years.
This substance for filling kept It's place
until about tifteon years ago, when 10 was
generally given up. The reason Tor aban-
doning tho use Of plaster Is thus given. 1t
was used not In Its dry state but mingled
with water, and allowed to set after Being
poured In between the castings This fii-
ing, 1t was found, attracted moisture from
the atmosphere and either produced oxida-
tion Of the metal In contact, or formed
sulphurlc acid of strength enough to corrode
the iron. II Ia not an uncommon thing to
find old safes that were filled in this way
with holes eaten through their panels
When 1t became apr ar 5nt that the set plas-
ter was corrodinG the metal, 1t was thought
that dry plaster might do, but, though u
poor conductor of heat, 1t was found defec-
tive In having no water to give OF, and
alum, which contained large percentage
Of water, was mixed with it and found to
answer the purpose very we'll. Some
twenty years ago before the use Of plaster
as filling was abandoned, the use of
hydraulic aud other cements was commen-
ced. The cement was simply mixed with
water and put in to SGT In tho same way as
plaster. The property of absorbing water
varies with tho different kinds of cement,
but that variety which absorbs the most
water is obviously the best fitted for filling
purposes. Some kinds of cement will
absorb one.third to ono-half their volume
OF water, while there Is kind used which,
1t is said, will absorb an equal volume OF
water, that Is, barrel of cement will absorb
barrel Of water. Cement at tho present
time scoms to be tho favorite filling with
most safe-makcrs, and 1t IL found not to
corrode the iron on account of the alkali
which Is In 1t, which has preservativo
tendency on that metal. Pure cement Is
used by tho best safc-makcrs, though it il
said some mix In sand, which Injuries tho
conducting properties. Asbestos has been
used, but was found to be not good
non-conductor, and was soon abandoned.
About twenty years ago Boston man TOOK
out a patont to line safe doors and fan ;es
with soapstone, but In practice IL was
found that, IN long g-continued fire, the
| soapBtone heated to very high tempra-
ture and retained Its hoat, 80 that 1t In turn
Was abaudOnnd II, 1870 q rntent wps
.unuu uuv' foI silu a.latrl,lcn. u tiIo pias.v1
| filling to plates suspended between the
walls, 80 that in shrinking Its diminished
size will not psrmit Its falling from its
place; patents were also taken out for the
use, for filling, of pure alumina; and also,
for the same purpose, of sulphate of iron
mixed with plaster of paris. In 1893 tho
following patents were taken out: For the
construction Of safe with two air, aud
steam tight castings, one within the other,
and with tho intermediate spaces filled In
with material capable of generating steam
under high heat, the latter melting fusi.
bic plugs In tho outer casing TO-. per-
nit tho exit Of tho steam; also for the use
of filling made Of plaster of paris set with q
solution Of starch; also for filing formed
Of compound Of >calsined and powdered
gypsum and alum In pieces embedded IN
tic plaster In such relative proportions that
the water Of capitalization III the alum
evolved by heat shall set the plaster (this
was tho alum safe already alluded toy; also
for the furnishing Of tho filing with cavi-
tics to prevent the rupture Of the parts
from the expansion of moisture by freezing.
In 1864 a patent was taken out for q fill
ing of alum In small Jumps rolled III plaster
and then imbedded la dry clay. In 1855,
filing Of epson salts, either alone or!coln-
bined with suphate Of lime, was obtained.