The Bloomfield times. [volume] (New Bloomfield, Pa.) 1867-187?, 1873-05-06
Alum-HOw Obtained.

TN some portions of Europe alum stone,
grayish colored mineral, is found in
large quantities, from which the best alum
of commerce is procured in Italy this
stone is obtained from quarries by blasting,
and, when exposed for short time to
moist atmosphere, becomes friable and
eventually fails to pieces. .......f
The first process in the manufacture of
this variety of alum is the erection of par
allel piles of these stones, arranged in reg
ularly formed layers on each side of which,
and in close proximity, channels are exca-
waited and filled with water. A gentle heat
is then applied, and the water sprinkled
over the heaps at frequent intervals. By
this treatment the stones soon commence to
pulverize, but the moistening is continued
for several weeks, as it facilitates the sepa-
ration of their constituent elements. When
completely pulverized, the powder is thor
oughly boiled in vessels specially prepared
for this purpose. This process causes a
subsistence of earthly ingredients, and an
evaporation of all volatile foreign substan-
ces. The liquid is then withdrawn into
other vessels, and allowed to remain un6is-
turbed until the alum appears in the form
of crystals, which is usually the case in the
course of few days. This is termed Ro-
man alum, and is regarded as the most val
liable variety in the Market because pos
sessing fewer Impurities than any other
1t can be readily recognized by the auburn
tint seen ON the surface, which is impaired
it by the presence of minute particles of
the sulphate of iron.
Another variety of alum is manufactured
from alum slate species Of sandstone
containing a large quantity of clay, which
is extensively disseminated throughout diff
ferent portions of the United States and
Canada. In it's preparation, the states, like
the alum rocks, are arranged in regularly
formed masses and subjected to a certain
amount of heat and moisture. AT Whitby,
| where the most extensive manufactures of
Europe are located, these masses are often
built to height of one hundred feet, with
a base of two hundred feet square. Owing
to the composition of these states, twelve
months, and often more, are required for
the burning process. After an artificial fire
has been continued for several weeks, no
additional food is necessary, as the chemi-
cal changes in the ingredients will furnish
sufficient material for combustion. When
thoroughly pulverized by this process the
powder is placed in large vessels Of water,
where the soluble salts they contain are
washed out, after which the liquor is boiled,
and, for the purpose of eliminating all i'm
purities, condensed by the agency Of heat
into powerful solution of copperas and
the sulphate of ammonia or basic alum
| This liquor thus condensed, is then con-
veyed into large tanks where the iron is
chemically separated and suitable alkali
added (the basic alum not possessing the
property of crystalization), which causes
the formation of crystals on the sides of
the tanks. These are again dissolved, and
the solution placed in casks around the
sides of which, in short time, the alum
crystals are formed, and these, when they
become free from moisture, are ready for
market. 1t is estimated that 6l9 tons of
alum slate are required to one ton of alum
! ~. Y. Mercantile Journal.
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been thwaring n
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thed old Dan Tucker"