IMPROVEMENTS IN THE MANUFACTURE OF SULPHURIC ACID
Year: 1864

page_text: PROVISIONAL SPECIFICATION left by George Davies at the Office of the
Commissioners of Patents, with his Petition, on the 11th February
1864. A communication from abroad by John Smith and John Richard
Savage, both of Philadelphia, Pennsylvania, United States of America.
I, GEORGE DAVIES, of No. 1, Serle Street, Lincoln's Inn, in the County
of Middlesex, and No. 28, St. Enoch Square, in the City of Glasgow,
Civil Engineer and Patent Agent, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN THE MANUFACTURE OF SULPHURIC ACID," (a
communication to me from [abroad by John Smith and John Richard
Savage, both of Philadelphia, Pennsylvania, United States of America,) to be
as follows:-
This Invention consists in concentrating sulphuric acid by submitting it to
the action of steam-heated leaden worms in leaden pans, also by introducing
the acid to a still containing a steam-heated leaden worm, thereby effecting
a great saving in the expense of manufacturing this important article of
commerce.
In order that the mode of carrying out this Invention and the advantages
of the same may be thoroughly understood, the usual mode of concentrating
sulphuric acid will first be described. When the acid in the bottom of what
are termed the receiving chambers has reached a density of 50 degrees
Beaumé, it is drawn off and permitted to flow into large rectangular pans of
sheet lead, the sides of which are turned up so as to give them a depth of
eight or nine inches. These are placed upon plates or tiles over a fire-place

page_text: the flue of which is extended under other pans arranged in successive steps
towards the chimney. In these the acid is evaporated by the heat of the
flame beneath the plates, and is gradually transferred by syphons from the
upper to the lower pans, till in the lowest it has acquired a density of about
61 degrees Beaumé. To raise the acid to the strength of concentrated oil
of vitriol of commerce, it has been deemed necessary hitherto to make use of
glass retorts or stills of platinum placed above a wood or coal fire. After the
acid has reached a density of about 66 degrees Beaumé, it is withdrawn
through glass syphons and received into the glass carboy. This mode of
concentrating sulphuric acid is most expensive for the following reasons:-
First, the leaden pans are soon deteriorated by the direct action of the
fire, and have to be constantly repaired or replaced.
Second, glass stills, although protected by iron casings, are constantly liable
to fracture, which not only causes a delay in the process of concentration, but
involves the expense of replacing them with new ones and the loss of expensive
quantities of acid.
Third, platinum stills are very costly, as one of moderate dimensions suitable
for the purpose cannot be purchased at a less cost than about £2000 (pounds
sterling).
Fourth, the necessity of maintaining a fire of uniform heat beneath the
pans and stills demands the consumption of a large amount of fuel.
The object of the present Invention is to concentrate the acid to the desired
density at less expense than by the usual process,-
Firstly, by subjecting it to the action of steam-heated worms in leaden
pans.
And, secondly, concentrating the acid to a greater density by introducing it
into a still containing a steam-heated worm.