Juniata sentinel and Republican. [volume] (Mifflintown, Juniata County, Pa.) 1873-1955, 1874-02-11
Scientific.
ALuM.-Alum earth, mineral deposit
in the brown coal formation.

in the brown coal formation.
The alum slate is dull earthly black
slaty mineral, of specific gravity "a
it contains some bituminous matter and
fossil remains, and is found in England,
the Netherlands, and Prussia.
The alum stone, called alunite, OF
obtuse rhombic form and white color.
1t has a vitreous and pearly luster,
yielding: alumina II per cent, sui
phuric acid % per cent, silica "A per
cent, potash 4 per cent, water per
cent total, 100. In 1866, / found it
between the gneiss and granite, in an
effiorescent state, at First avenue and
5lst street, New York. The mineral is
found in lava and trachytic rocks at
Talfa near Rome, in Hungary, and in
Auvergne, France. This material was
used ], 900 years ago for producing the
alum, and is called the Roman alum.
The aluminite, found abundantly in
Prussia at Halle, and at Epernay in
France, is also called websterite, and
contains alumina 80 per cent, sulphuric
acid "a per cent, water 46 per cent. 1t
is white and opaque; it adheres TO the
tongue, and has a specific gravity of
90. 1t is rather abundant in the locali-
ties named.
The many applications OF alum in the
arts are due to the alumina having great
affinity for many coloring and other
vegetable matters, for gelatin, etc. !;
and in the preparation Of lakes, it forms
an insoluble precipitate of alumina with
vegetable colors. 1t is also used In
preparing white leather by its action on
gelatin. for clarifying water, as an ad-
dition to paste used by bookbinders,
for preventing the depredations OF In
sects, in fireproof safes as filling, etc.
Alum has been described by authors as
early SIS Pliny and Dioscorides. Boer-
have gives a very extensive description
of it. and says:
Alum is a real fossil, procured either
from hard faky stone, found deep in
the ground, and so pregnant with sui
phur and bitumen as easily to take fire
or form bituminous and combustible
earth, which yields noxious flame and
a sulphurous stencil. III exposed for a
month in the open air, it crumbles into
powder, and thus becomes disposed for
the generation of alum, which before it
was not If dissolved in water, it may
be precipitated by adding Il fixed or
volatile alkali and it then produces a
new salt, which is the alkali and the
fossil matter together. In England,
Italy, and Flanders, alum is principally
produced. He also says ''that alum
has a sharp, rough, styptic taste. Its
crystals are octagonal, four of the sides
being hexagonal, and the other four
triangular, surfaces. In Italy (at Civita
Vecchia and at Solfatara, near Patella),
the alum is manufactured from the ma
tural substance in summer time.
Let me add few words more about
alum and its physical and medicinal
properties. Alum is a white, slightly
effiorescent salt, it crystalizes easily in
octahedrons, but may be made to crys-
talize in cubes, if an excess of ammonia
is added to the solution, which must be
carefully evaporated it dissolves in
warm water, say in three fourths of its
weight of boiling water. tits insoluble
in alcohol, and has specific gravity of
III; it reddens itmus, and changes
the tints of the blue petals of plants to
green it assumes an aqueous fusion
when heated to 2120 Fab. Exposed to
red heat, it gives off oxygen with sui
phurous acid. 1t forms pyrophorous
when calcined with fine charcoal, and
spontaneously forms an infammable
substance. There are several varieties
known in commerce, among Others, the
Roche alum, which originally came from
Rocca in Syria, of a pale rose color !;
and the Roman alum, which has always
been considered as the purest. Five
thousand tuns are still annually manu-
factured.
Alum is incompatible with the aka
lies and their carbOnates, lime and lime
water, magnesia and its carbonate, tar
trate of potash, and acetate of lead. 1t
is an astringent and antispasmodic in
large doses, it is purgative and emetic.
In cases of hGmorrhage, sweats, dia-
betes, chronic dysentery and diarrhea,
1t Is used as an astringent. 1t is used
as purgative in the painters and ner-
vous colics. Alum is also sometimes
used for the aduiteration of bread, with
a view to increase the whiteness, but in
very small doses.
1t may be stated, in conclusion, that
great many minerals, known by miR
eralogists as oxygen compounds, the
unisilicates, hydro-silicates, and some
bisilicates, contain the oxide of alumni
mum or alumina as one of the component
parts. The family known as zeolites,
such as laumonite, natrolite, analcite,
mesolite, scolecite, thompsonite. gmel-
mite, phillipsite, harmotome, stilbite
and many more of this class each con-
tain from 20 TO 80 per cent of alumina,
pachnolite % per cent, and staurolite
30 per cent. kyanite contains G4 per
cent. Several mineral springs in the
United States, in Virginia, contain the
alum in solution from 20 to 20 per cent,
and are used in medicine.
L may say that alumina exists in the
most common as well as the most pre-
cious minerals. White clay or kaolin is
found in many localities in the United
States to very large extent. i have
visited many deposits in Vermont, near
Brandon, in Massachusetts, in Pennsyl-
vania, at Jacksonville, Ala, and in
South Carolina. At Bath / saw large
deposits of fine quality, and 10000
tuns are annually brought to this city
for papermakers' use. At Aiken, S. c.,
large deposits are yet undeveloped. At
Perth Amboy, various qualities have
been dug out for the last so years from
strata 20 feet thick. 1t is found in the
coal, tertiary, metamorphic and older
formations. Stourbridge clay, so in
dispensable for glass pots, is principally
brought from England. Alum is very
branch of commerce. England
produces annually 10, 900 tuns, and Ger
many 10, 900: and in the United States
about 5000 tuns are manufactured
Scientific american.
A SIMPLE method for illustrating the
production of cold By evaporation is
described as follows The neck of
bottle filled with liquid bisulphide of
carbon is closed with q cork. thrnurh