A NEW OR IMPROVED METHOD Of PRODUCING ANHYDROUS SULPHURIC ACID
Year: 1880

page_text: LETTERS PATENT to William Lloyd Wise, of 7, Whitehall Place, in the City of
Westminster, for an Invention of " A NEW OR IMPROVED METHOD Of
PRODUCING ANHYDROUS SULPHURIC ACID." A communication from abroad by
Dr. Johannes August Wilhelm Wolters, of Dresden, Kingdom of Saxony,
German Empire.
PROVISIONAL SPECIFICATION left by the said William Lloyd Wise at the
Office of the Commissioners of Patents on the 21st January 1880.
"
WILLIAM LLOYD WISE, of 7, Whitehall Place, in the City of Westminster.
A NEW OR IMPROVED METHOD OF PRODUCING ANHYDROUS SULPHURIC ACID."
(A communication from abroad by Dr. Johannes August Wilhelm Wolters, of
Dresden, Kingdom of Saxony, German Empire.)
This Invention consists in the production of anhydrous sulphuric acid by the
action of hydrate of sulphuric acid upon anhydrous bisulphate of alcali.
Anhydrous bisulphate of alcali (SO, R, + SO,) is mixed with hydrate of sulphuric
acid, and from this, after being partially changed into hydrous bisulphate of alcali
and anhydrite, the latter is gained by distillation. The residuary acidated salt is
by heating process turned into anhydrous acidated salt, and may henceforth be
used for further production of anhydrous sulphuric acid.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said William Lloyd Wise in the Great Seal Patent Office on the 19th
July 1880.
.
WILLIAM LLOYD WISE, of 7, Whitehall Place, in the City of Westminster.
"A NEW OR IMPROVED METHOD OF PRODUCING ANHYDROUS SULPHURIC ACID."
(A communication from abroad by Dr. Johannes August Wilhelm Wolters, of
Dresden, Kingdom of Saxony, German Empire.)
This Invention consists in a new method of producing anhydrous sulphuric acid
by the action of hydrated sulphuric acid upon anhydrous bi-sulphate of an alkali,
based upon the property of the latter (discovered by my foreign correspondent) of
converting hydrated sulphuric acid into anhydrous acid and hydrated bi-sulphate
of the alkali.
The process is as follows:-
Hydrated bi-sulphate of an alkali is converted by heating up to 300 to 400° C.
in any well-known manner until by expulsion or driving off of the water it is
converted into anhydrous bi-sulphate of alkali. This conversion will be most
easily effected if worked at a low temperature (say about 350° C.) for a long time
instead of heating to a high temperature for a short time.
It is necessary to continue this treatment of the sulphate until at least 90 per
cent. of the hydrated bi-sulphate is converted into an anhydrous state.
This anhydrous bi-sulphate is then mixed with a quantity of hydrated sulphuric
acid in the proportion of two parts by weight of hydrated sulphuric acid to three
parts by weight of anhydrous bi-sulphate, after which the anhydrous sulphuric
acid, SO,, is distilled off, which is effected at a temperature of about 250 to 350° C.;
a part of the hydrated sulphuric acid is then distilled or driven off at a higher
temperature (a little above 350° C.), and the remaining hydrated bisulphate is
subsequently converted into anhydrous sulphate by driving off the water.
The hydrated sulphuric acid employed in the above process is in the form of
commercial sulphuric acid, concentrated as much as possible (about 98 per cent.
monoliydrated). The hydrated bi-sulphate of the alkali as obtained in the above
process is used for the preparation of a fresh quantity of anhydrous sulphuric acid
by re-heating it, as above described. In this process about 40 per cent. of the acid
added is obtained as SO,, 57 to 58 per cent. as hydrate, and 2 to 3 per cent. will
evaporate with the water during the conversion of the hydrated sulphate into
anhydrous sulphate.
It is to be remarked there is a radical difference between this improved process
and the process described in hand books, according to which latter process the
anhydrous bi-sulphate of the alkali is split up at a high temperature (up to 1000° C.)
into neutral sulphate and free anhydrous acid, which further splits up into
sulphurous acid and oxygen, for which reason it has never come into constant use.
The remaining neutral sulphate might be converted by the addition of acid and by
heating into anhydrous sulphate. The anhydrous acid is separated according to
the old method by means of a very high temperature, whereas according to this
new method the freeing or liberating of the anhydrous acid is effected by com-
binations of the water with a third body or material, which takes place at a
proportionately low temperature. According to the old method in the hand books,
after the addition of new acid during the heating process, first the water and then
the anhydrate was to be distilled off, whereas with this improved method, after the
addition of acid, first the anhydrate is distilled off and then the water, or the
hydrated acid is expelled. The entire process is effected in clay retorts of cylin-
drical form, the retorts being glazed inside and out.

page_text: Having described the nature of the said Invention and explained the manner of
carrying it into practical effect as communicated to me as aforesaid, I would have
it understood that what I claim as the Invention secured to me under the Letters
Patent hereinabove in part recited is,―
The above described improved method of producing anhydrous sulphuric acid.
In witness whereof, I, the said William Lloyd Wise, have hereunto set my
hand and seal, this Nineteenth day of July, in the year of our Lord One
thousand eight hundred and eighty.
W. LLOYD WISE. (L.S.)