The morning news. [volume] (Savannah, Ga.) 1887-1900, 1899-05-27
PROCESSES OF MAKING SALT.
ANCIENT AND MODERN SYSTEMS OF
REDUCING BRINE.

and Vacuum Pans-Antiauity of the
Denosits-Improved Quality of the
American Product.
From the New York Sun.
Although the industry of catching birds
bv shrinking salt on their tails has never
attained the development which it once
promised to achieve there are enough
other demands for this article of COM
merce to make its production an exten-
Give. if not a profitable, business. IN
round numbers, $500, 100000 pounds Of sat
are needed every year in this country
to offset the inherent freshness Of Ameri-
cans, and Of other people, to whom we
sell cured hams and the like. OF this
amount-about fifty pounds per capita-an
eighth. or more than an eighth, Is import
ed, and all the rest is homemade. As yet
scarcely more than / per cent. of our
American product is sent abroad but this
branch Of the trade is slowly increasing
and the importation of salt is steadily
diminishing.
There are two general sources from
which salt is obtained, natural brines and
solid deposits. number of theories have
been advanced to account for the latter.
The general impression among scientific
men is that rock salt has been formed
by evaporation from ancient seas which
had become inc.osed in some way. In con-
firmation of this notion it is pointed out
that deposits are being made to-day al
the bottom OF several weil-known salt
1plfn LtfaF hsavr t.rsa1 4
as to the applicability of the explanation
to such thick strata as those at Stass-
furt, Germany, 1850 feet deep, and at
Sperenberg. near Berlin, $500 feet thick
However this may be, the substance is
found, in greater or less purity, in all
parts of the world, The minerals asso-
ciated with il are those which are apt
to exist in the principally chloride Of so
dunn. But chlorides of lime and mag
nesium, sulphate Of lime and magnesium
and even minute quantities of iodides and
bromides are usually mingled with the
chief constituent.
Rock Salt.
For a long time Turks Island. in the
West indies, was a cOpious contributor to
this country's supply of rock sat. But a
number of mines are now being worked in
the United States. The most famous at
present are those at Livonia, N. Y. The
salt is taken out In solid chunks, ground
passed through sleeves of different mesh
10 be graded according to coarseness-and
put up in bags or barrels. There is ia
nous deposit in Louisiana, much nearer
the surface of the ground and more easily
worked which will be an important pro-
ducer some day
There are many salt deposits In this
country which are mode available not by
mining, but by the pumping of brine from
their vicinity. Through a large part of
Michigan, for instance and from the cen.
tral part of New York state out as far as
Buffalo. there are beds varying in thick
ness from liz to 800 feet, and lying from
COZ 10 2o00 feet below the surface An
through these Two regions. as well as in
Northern Ohio, wells have been sunk, and
the brine IS pumped up like oil. Fresh wa
ter springs supply the water. no doubt
and this, lowing over and through the
sold salt, dissolves the latter and puts a
within mans reach. In few places there
are salt springs which eject their mineral
laden fluids without coaxng.
Five Principal Methods.
There are five principal methods of
treating brines in order to get the salt
from them. one of the oldest systems is
that so extensively employed at Syracuse
The brine is poured into enormous, shall
low, wooden watts, and exposed TO the sun
and wind to dry. Whenever there is a
rainstorm covers are drawn over them to
exclude additional water. Precautions
are also taken against the admission Of
dirt The product obtained in this way
is called solar salt" Owing to the slow
ness of the evapora teive process the grains
thus formed are coarse
To hasten matters artificial heat is Of
ten used For instance, rows of kettles
are arranged so that coal fires may be
maintained under them. AS the water
boils off the salt crystallizes in the bot
tom of the receptacle BY regulating the
degree of heat applied, and providing for
marked differences of temperature in two
sets OF kettles, grains of different sizes can
be secured-the finer ones resulting from
the more rapid evaporation. This meth
cd Is an ancient one.
In Wyoming county, New York, artlh-
eial heat is used In another may. Metal
pans, about l25 feet long p feet wide ana
perhaps 21a feet deep, are warmed by fur
naces directly under them. Coal is used
in the latter. The heat being applied d-
rectiy the system is known as the direct
heat plan. 1t is further characteristic
OF the process that il is conducted with
open pans. An indirect mode of bring
ing the heat to bear on the brine is to line
the watts. which are smaller receptacles
than those just described, with steam
pipes, which run around the inner edge of
the same and transmit their heat TO The
fluid. The indirect heat apparatus is
called a "grainer"
Finally, 1t has been found feasible to
save fuel and obtain purer salt by in
closing the brine in tight vessel from
which the air has been almost entirely
exhausted. This is call vacuum pan
IT is a well-known fact that evaporation
takes place at a lower temperature when
the air pressure is reduced than at ordi-
nary pressures. This is the reason why
water boils at a lower temperature on a
mountain top than on a plain. In the
vacuum pan the work can be done by
heating the brine to only liz degrees. Vac.
uum pans are in service at three places