IMPROVEMENTS IN TILE PREPARATION OF HYDROCHLORIC ACID
Year: 1880

page_text: PROVISIONAL SPECIFICATION left by the said Ernest Solvay at the Office
of the Commissioners of Patents on the 25th February 18S0.
1
ERNEST SOLVAY, of Brussels, in the Kingdom of Belgium, Manufacturer.
"IMPROVEMENTS IN TILE PREPARATION OF HYDROCHLORIC ACID."
My Invention consists in the employment of chloride of calcium for the purpose
of obtaining hydrochloric acid free from water and vapour of water. This result
is of great importance in those branches of manufacture in which hydrochloric acid
is to be converted into chlorine.
I have discovered that from the affinity which chloride of calcium has for water, a
sufficiently concentrated solution of the said chloride of calcium has the property of
retaining water at a temperature at which it allows hydrochloric acid to escape, and
that owing to this property hydrochloric acid may be readily obtained in a dry
state under conditions when it would be impossible to do so otherwise.
I utilize the property above mentioned either when it is required to collect
hydrochloric acid mixed with gases which are to be separated from it, or when
having separate hydrochloric acid or hydrochloric acid accompanied by other gases
it is required to remove only the water or vapour of water carried away with it;
or again when it is required to drive off the hydrochloric acid from the water in
which it is usually in solution (liquid hydrochloric acid).
First Case. The use of chloride of calcium when the hydrochloric acid is mixed
with gases from which it has to be separated, such as the products of combustion or
chlorine.
Water is generally used for the purpose of collecting hydrochloric acid, which
dissolves therein in large quantities, but this method has the disadvantage of not
allowing the said gas to be produced afterwards in a dry state, for, when the liquid
hydrochloric acid thus obtained is distilled, water as well as gas is evolved at a
certain time unless the distillation be arrested before all the acid is thrown off from
the solution.
I substitute for water a sufficiently concentrated solution of chlorido of calcium,
which absorbs the hydrochloric acid and the water and vapour of water which may
r

page_text: accompany it, but not the foreign gases which may be with them. If necessary
the solution may be cooled to effect a complete condensation.
By afterwards suitably heating the said solution all the hydrochloric acid may
be driven off before the vapour of water begins to escape. If the acid to be
collected be accompanied by more or less water or vapour of water, a more or less
concentrated solution of chloride of calcium will naturally be used, so that the
water, which will be collected all the more readily as the solution is less diluted, will
not be in such excess as to prevent the hydrochloric acid being evolved in a dry
state by complete distillation.
The present case is applicable chiefly.—
Firstly. When it is desired to separate bydrochloric acid from the products of
combustion, either in Leblanc's process during the manufacture of sulphate of soda,
or in the process which consists in setting free hydrochloric acid from a mixture of
chloride of calcium and silicate of alumina by calcination, which process is
described in the Specification of Letters Patent granted to me, dated the Ninth
day of January 1877, No. 91.
Secondly. When it is required to separate hydrochloric acid from chlorine and
from air and nitrogen, which may accompany them in those processes in which
guscous hydrochloric acid is converted into chlorine, by mixing the hydrochloric acid
with atmospheric air, and causing the mixture to pass over certain substances.
In this process it is useful to be able to collect in a dry state the hydrochloric
acid which escapes, because the reaction has not been complete as is generally
the case.
Second Case. The use of chloride of calcium when it is only required to liberate
the hydrochloric acid from the water or vapour of water which accompanies it.
When having hydrochloric acid with or without other gas it is required merely
to separate it from water or vapour of water, the operation may be carried out as
herein before described, that is to say, by condensing and distilling the hydrochloric
acid, but I have invented the means of superseding the condensation of the
hydrochloric acid.
For this purpose I keep the solution of chloride of calcium at a temperature at
which, by reason of its affinity, it condenses water or vapour of water without
retaining the bydrochloric acid, so that the water and vapour of water are retained
whilst the bydrochloric acid pursues its way with the other non condensible gases,
if there be any such gases.
The solution of chlorido of calcium is diluted successively by the water it
absorbs, and it is kept at a suitable degree of concentration by adding to it from
time to time solid or very much concentrated chloride of calcium. By this means
the necessity of interrupting the operation to regenerate the chloride of calcium is
obviated.
The operation may be made continuous, either in a single apparatus arranged
vertically or in several apparatus disposed to work systematically, by causing the
solution of chloride of calcium to flow in an opposite direction to the gaseous
current. In all cases the diluted chloride of calcium removed after the operation
is subjected to concentration, so as to be able to serve again in other operations.
Third Case. The use of chloride of calcium for driving out hydrochloric acid
from the water, in which it is usually in solution.
When having ordinary liquid hydrochloric acid it is desired to drive out the
bydrochloric acid completely in a dry state, I dissolve chloride of calcium in the
said liquid bydrochloric acid, and then I treat the solution as hercinbefore described,
and the hydrochloric acid alone is evolved.
Moreover I use well-known apparatus and processes to effect the condensation of
a gas in a liquid.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Ernest Solvay in the Great Seal Patent Office on the 11th August
1880.
ERNEST SOLVAY, of Brussels, in the Kingdom of Belgium, Manufacturer.
"IMPROVEMENTS IN THE PREPARATION OF HYDROCHLORIC ACID."
My Invention consists in the employment of chloride of calcium for the purpose
of obtaining hydrochloric acid free from water and vapour of water. This result
is of great importance in those branches of manufacture in which hydrochloric
acid is to be converted into chlorine.
I have discovered that from the affinity which chloride of calcium has for water, a
sufficiently concentrated solution of the said chloride of calcium has the property of
retaining water at a temperature at which it allows hydrochloric acid to escape, and
that owing to this property hydrochloric acid may be readily obtained in a dry
state under conditions when it would be impossible to do so otherwise.
I utilise the property above mentioned either when it is required to collect
hydrochloric acid mixed with gases which are to be separated from it, or when
having separate hydrochloric acid or hydrochloric acid accompanied by other gases
it is required to remove only the water or vapour of water carried away with it;
or again when it is required to drive off the hydrochloric acid from the water in
which it is usually in solution (liquid hydrochloric acid).
First Case. The use of chloride of calcium when the hydrochloric acid is mixed
with gases from which it has to be separated, such as the products of combustion or
chlorine.
Water is generally used for the purpose of collecting hydrochloric acid, which
dissolves therein in large quantities, but this method has the disadvantage of not
allowing the said gas to be produced afterwards in a dry state, for, when the liquid
hydrochloric acid thus obtained is distilled, water as well as gas is evolved at a
certain time, unless the distillation be arrested before all the acid is thrown off from
the solution.
I substitute for water a sufficiently concentrated solution of chloride of calcium,
which absorbs the hydrochloric acid and the water and vapour of water which may
accompany it, but not the foreign gases which may be with them. If necessary
the solution may be cooled to effect a complete condensation. By afterwards
suitably heating the said solution all the hydrochloric acid may be driven off
before the vapour of water begins to escape. If the acid to be collected be
accompanied by more or less water or vapour of water, a more or less concentrated
solution of chloride of calcium will naturally be used, so that the water, which
will be collected all the more readily as the solution is less diluted, will not be in
such excess as to prevent the hydrochloric acid being evolved in a dry state by
complete distillation.
The present case is applicable chiefly,-
Firstly. When it is desired to separate hydrochloric acid from the products of
combustion, either in Leblanc's process during the manufacture of sulphate of soda,
or in the process which consists in setting free hydrochloric acid from a mixture of
chloride of calcium and silicate of alumina by calcination, which process is
described in the Specification of Letters Patent granted to me, dated the Ninth day
of January 1877, No. 91.
Secondly. When it is required to separate hydrochloric acid from chlorine and
from air and nitrogen, which may accompany them in those processes in which
gaseous hydrochloric acid is converted into chlorine, by mixing tho hydrochloric
acid with atmospheric air, and causing the mixture to pass over certain substances.
In this process it is useful to be able to collect in a dry state the hydrochloric

page_text: acid which escapes, because the reaction has not been complete as is generally
the case.
Second Case. Tho use of chloride of calcium when it is only required to liberato
the hydrochloric acid from the water or vapour of which accompanies it.
When having hydrochloric acid with or without other gas it is required merely
to separate it from water or vapour of water, the operation may be carried out
as hereinbefore described, that is to say, by condensing and distilling the
hydrochloric acid, but I have invented the means of superseding the condensation
of the hydrochloric acid.
For this purpose I keep the solution of chloride of calcium at a temperature at
which, by reason of its affinity, it condenses water or vapour of water without
retaining the hydrochloric acid, so that the water and vapour of water are retained
whilst the hydrochloric acid pursues its way with the other non-condensible gases,
if there be any such gases.
The solution of chloride of calcium is diluted successively by the water it
absorbs, and it is kept at a suitable degree of concentration by adding to it from
time to time solid or very much concentrated chloride of calcium. By this means
the necessity of interrupting the operation to regenerate the chloride of calcium is
obviated. The operation may be made continuous, either in a single apparatus
arranged vertically, or in several apparatus disposed to work systematically by
causing the solution of chloride of calcium to flow in an opposite direction to the
gascous current. In all cases the diluted chloride of calcium removed after the
operation is subjected to concentration, so as to be able to serve again in other
operations.
Third Case. The use of chloride of calcium for driving out hydrochloric acid
from the water in which it is usually in solution.
When having ordinary liquid hydrochloric acid it is desired to drive out the
hydrochloric acid completely in a dry state, I dissolve chloride of calcium in tho
said liquid hydrochloric acid, and then heat the solution, as herein before described,
and the hydrochloric acid alone is evolved.
Morcover I use well known apparatus and processes to effect the condensation of
a gas in a liquid.
Having now described the nature of my said Invention, and the manner of
performing the same, I claim as my said Invention of improvements in the
preparation of hydrochloric acid,―
1. Substituting for water a solution of chloride of calcium for the purpose of
collecting hydrochloric acid, whatever may be the gases which accompany it,
substantially as hereinbefore described.
2. The employment of a solution of chloride of calcium for the purpose of
separating hydrochloric acid from the water which accompanies it, substantially as
described.
3. The addition of chloride of calcium to water containing hydrochloric acid, for
the purpose of causing the said hydrochloric acid to evolve in a dry state,
substantially as described.
In witness whereof, I, the said Ernest Solvay, have hereunto set my hand
and seal, this Seventh day of August, in the year of our Lord One
thousand eight hundred and eightv.