DORRADATION OF HYPOSULPHITE OF LIME
Year: 1865

page_text: LETTERS PATENT to James Cochran Stevenson, of South Shields, in the
County of Durham, Chemical Manufacturer, for the Invention of
IN DORRADATION OF HYPOSULPHITE OF LIME."
Sealed the 15th September 1865, and dated the 18th March 1865.
PROVISIONAL SPECIFICATION left by the said James Cochran Stevenson
at the Office of the Commissioners of Patents, with his Petition, on the
18th March 1865.
I, JAMES COCHRAN STEVENSON, of South Shields, in the County of Durham,
Chemical Manufacturer, do hereby declare the nature of the said Invention
for "IMPROVEMENTS IN THE PREPARATION OF HYPOSULPHITE OF LIME," to be as
follows:-
This Invention has for its object improvements in the preparation of hypo-
sulphite of lime. The late Dr. Jullion obtained a Patent in 1861 (No. 380,
9th February 1861) for a process in which a solution of hyposulphite of lime
was produced from the yellow liquor obtained by the oxidation of soda waste.
These improvements relate to the treatment of the solution of hyposulphite
of lime thus or otherwise obtained in order to obtain the salt in a dry form
suitable for the market. If the solution is evaporated by heat in the open air
it decomposes. According to my Invention I evaporate it in a vacuum pan
made of iron, similar in construction to that used in the manufacture of sugar.
The solution is boiled at a temperature of 110° Fahrenheit, until it reaches

page_text: the specific gravity of 1-480, when it is run out, settled, and allowed to
crystallize. The crystals obtained, which are not sufficiently pure, are re-
dissolved in a water bath at a temperature of 110° Fahrenheit, and to a
specific gravity of 1.450, and crystallized a second time, or the salt may be
redissolved in cold water and then again concentrated to the crystallizing
strength above mentioned in the vacuum pan.
The mother liquors are
returned to the vacuum pan.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said James Cochran Stevenson in the Great Seal Patent Office on
the 15th September 1865.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JAMES
COCHRAN STEVENSON, of South Shields, in the County of Durham, Chemical
Manufacturer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Eighteenth day of March, in the year of our Lord
One thousand eight hundred and sixty-five, in the twenty-eighth year of Her.
reign, did, for Herself, Her heirs and successors, give and grant unto me, the
said James Cochran Stevenson, Her special licence that I, the said James
Cochran Stevenson, my executors, administrators, and assigns, or such others.
as I, the said James Cochran Stevenson, my executors, administrators, and
assigns, should at any time agree with, and no others, from time to time and
at all times thereafter during the term therein expressed, should and lawfully
might make, use, exercise, and vend, within the United Kingdom of Great
Britain and Ireland, the Channel Islands, and Isle of Man, an Invention for
"IMPROVEMENTS IN THE PREPARATION OF HYPOSULPHITE OF LIME," upon the
condition (amongst others) that I, the said James Cochran Stevenson, my.
executors or administrators, by an instrument in writing under my, or their,
or one of their hands and seals, should particularly describe and ascertain
the nature of the said Invention, and in what manner the same was to
be performed, and cause the same to be filed in the Great Seal Patent
Office within six calendar months next and immediately after the date of the
said Letters Patent.
NOW KNOW YE, that I, the said James Cochran Stevenson, do hereby
declare the nature of the said Invention, and in what manner the same
is to be performed, to be particularly described and ascertained in and by
the following statement thereof, that is to say :-

page_text: This Invention has for its object improvements in the preparation of hypo-
sulphite of lime. The late Dr. Jullion obtained a Patent in 1861 (No. 380,
9th February 1861) for a process in which a solution of hyposulphite of lime
was produced from the yellow liquor obtained by the oxidation of soda waste.
The soda waste was exposed in a thin layer to the action of air and moisture,
and was repeatedly turned over. The yellow liquid is then obtained from it
by lixiviation. This liquid was saturated with sulphurous acid gas, and so
sulphur was precipitated, and a solution of hyposulphite of lime was
produced.
These improvements relate to the treatment of the solution of hyposulphite
of lime thus or otherwise obtained in order to obtain the salt in a dry form
suitable for the market. If the solution is evaporated by heat in the open air
it decomposes. According to my Invention I evaporate it in a vacuum pan
made of iron, similar in construction to that used in the manufacture of sugar.
The vacuum maintained within the pan should be such that a mercurial
barometer in the pan will mark only from half an inch to one inch pressure.
The solution is boiled at a temperature of 110° Fahrenheit until it reaches the
specific gravity of 1-480, which is ascertained by drawing samples from time
to time, when it is run out, settled, and allowed to crystallize. The crystals
obtained, if they are not sufficiently pure, are redissolved in a water bath at
a temperature of 110° Fahrenheit, and the quantity of water employed to
dissolve them is such that the solution may be of a specific gravity of 1.450,
and this is then crystallized a second time; or the salt may be redissolved in
cold water, and then again concentrated to the crystallizing strength above
mentioned in the vacuum pan, but the dissolving the crystals in the water
bath is simpler, and I therefore prefer it. The mother liquors are returned
to the vacuum pan until they become so impure as to be no longer worth
working.
In witness whereof, 1, the said James Cochran Stevenson, have hereunto
set my hand and seal, this Eighth day of September, in the year
of our Lord One thousand eight hundred and sixty-five.
Witness,
HENRY MARTIN.
JAMES COCHRAN STEVENSON. (L.S.)