IMPROVEMENTS IN THE MANUFAC- TURE OF SULPHATES OF SODA
Year: 1876

page_text: PROVISIONAL SPECIFICATION left by William Stevens Squire at the Office
of the Commissioners of Patents on the 27th April 1876.
WILLIAM STEVENS SQUIRE, Manufacturing Chemist, of 37, Acacia Road, Regent's
Park, London, in the County of Middlesex. "IMPROVEMENTS IN THE MANUFAC-
TURE OF SULPHATES OF SODA."
In the process generally employed in the manufacture of sulphate of soda the
mixture of common salt and sulphuric acid after being boiled down in an iron pot
heated by fire from beneath is pushed or thrown into a muffle or close furnace or
roaster heated to redness, in which it is stirred about by manual labour until the
decomposition of the salt by the sulphuric acid is complete.
According to this Invention I accomplish the stirring about of the mixture by
mechanical means. I fill up the corners of the muffle furnace so as to make the bed
circular in form, and I build the arches of the furnace in such a way that a small
aperture about 7 inches in diameter is left in the small or lower arch, imme-
diately over the centre of the circular bed. On this hole I place a cast-iron tube of
about the same diameter, provided with a flange at the lower end, fitting close on
to the upper surface of the lower arch, and I surround this pipe with about nine
inches of brick work to protect it from the excessive heat. Through this iron tube,
which projects completely through the large or upper arch, passes a cast-iron shaft
3 or 4 inches in diameter, which is hung in two bearings fixed above the furnace,
and quite independent of it, so that the bottom end of the shaft is about an inch
from the tile bed of the furnace, and can revolve quite independently of the furnace
and without touching it at any point.
In order to avoid any escape of gas through the iron tube it is provided at the
top with a circular trough or tube, into which a cap projecting from and surround-
ing the vertical shaft fits very loosely. When this trough is filled with strong
sulphuric acid or fine sand the tube is completely closed, and no gas can escape.
The shaft is provided at its lower extremity with radiating arms, on each of which
are fastened three or four vertical teeth of peculiar construction, so arranged that
those on the different arms do not follow in each other's wake, but successively pass
over every part of the bed. The section of these teeth resembles two triangles, an
obtuse and an acute one, placed base to basc. The obtuse one forms the front
of the tooth the acute one is behind, but is bent inwards towards the central shaft.
The effect of this arrangement is that when the shaft is caused to revolve by means

page_text: of suitable gear the sulphate is thrown slightly inwards by the slightly inclined
face of the hinder part of the tooth, and thus the tendency of the charge to be
gradually thrown outwards by centrifugal force is corrected, and the distribution
over the bed of the furnace remains perfect.
After the calcination of the charge is complete the motion of the shaft is reversed,
and owing to the great inclination of the faces of the tooth then presented to the
sulphates the charge is rapidly thrown to the sides, and can be allowed to discharge
itself by apertures either in the edge of the bottom of the bed or in the sides of
the furnace. By this arrangement it is possible to retain the advantages of the
close or muffle furnace constructed entirely of brickwork and heated on all sides.
No iron pan or bed or iron work is required in its construction beyond the usual
exterior binders, and this brickwork is not subject to shocks or vibration from the
action of the machinery, which at no point comes into contact with it.