IMPROVEMENTS IN THE MANUFACTURE OF CHLORIDE OF LIME OR BLEACHING POWDER
Year: 1857

page_text: application for Letters Patent was not given within the time prescribed
by the Act.)
PROVISIONAL SPECIFICATION left by Jonathan Burnett at the Office of
the Commissioners of Patents, with his Petition, on the 29th July
1857.
I, JONATHAN BURNETT, of 18 Side, Newcastle-upon-Tyne, do hereby declare
the nature of the Invention for "IMPROVEMENTS IN THE MANUFACTURE OF CHLORIDE
OF LIME OR BLEACHING POWDER," to be as follows:-
The process now most commonly in use for the manufacture of chloride
of lime or bleaching powder, consists in the production of chlorine gas by
saturating the black or peroxide of manganese with muriatic acid, or a
mixture of the peroxide of manganese and common salt in certain proportions
with sulphuric acid, the chlorine gas given off in both of these processes being
afterwards absorbed by quicklime. The apparatus required consists of a set
of vessels called stills, in which the chlorine gas is produced by the combina-
tion of the peroxide of manganese with the other ingredients; and of another
set of vessels called chambers or receivers containing quicklime, which absorbs
the chlorine gas as it is produced in stills, the gas being conveyed from the
stills to the chambers by leaden or earthenware pipes. These vessels are
constructed of various sizes and shapes and of different materials, but usually
of stone. Each still is connected with a separate chamber (unless the
chamber be of large dimensions, when two or more stills are connected to

page_text: one of such chambers). The stills are recharged with fresh materials as soon
as the chlorine gas has all been expelled and the charge is withdrawn from the
chambers when the lime is saturated with the chlorine gas, two or three
chargings of the stills being necessary generally to complete the process.
Now, it will easily be understood that should the chlorine gas be generated
rapidly in the stills by mixing the materials too quickly together, or should
the lime in the chamber be nearly saturated with the gas, the still or stills
being connected with only one chamber, and the absorbing surface of the lime
being consequently very limited, that at such times the chlorine gas would be
produced more rapidly than it could be absorbed, and that a portion of it
would be wasted by leakage. To prevent this the materials must be brought
together very gradually, by which much time is lost in the process; and when
the charge in a chamber is nearly saturated, the gas is occasionally in part
diverted into another chamber containing a pressure charge of lime. It will
also be evident, that during the time the stills are being discharged of their
waste contents and recharged with fresh materials, no chlorine gas being
generated and sent to the chambers, the progress of the absorption will be
interrupted, causing a further loss of time. The chlorine gas is also liable to
vary in temperature, and to become too moist while the last portion of it is
being driven off by the action of steam on the charge in the stills, by which
the bleaching powder is frequently injured in quality. Now, to remedy these
defects in the present process, I propose, instead of working these stills and
chambers detached, as is now done, to work them all or any convenient
number of them in common, collecting the chlorine gas as it is produced in
the stills into one main or common pipe, which would convey the gas either
directly to the chambers, or what would be better, to a common reservoir of
any convenient size, in which it might be cooled and purified from the
muriatic acid gas and vapour it generally contains, by a small stream of
water running through the reservoir. From this reservoir the gas would then
be conveyed by another main or common pipe to the chambers containing the
lime. Thus the stills and chambers would form one common system. In
order to connect them with or disconnect them from this common system
when necessary during the time the stills or chambers are being recharged,
each set of vessels would be provided with cocks, lute syphons, or any other
convenient apparatus to effect this purpose. The advantages to be gained
from this plan would be a greater efficiency of the apparatus, as the chlorine
gas might be produced much more rapidly in the stills than at present
without any risk of its being wasted, on account of each still being connected
with a great many chambers (instead of only one), by which the absorbing

page_text: surface of the lime would be increased and the pressure maintained at a more
uniform rate, by reason of the greater space into which the gas would be con-
veyed, and by a continuous stream of gas being kept up into every chamber,
by which the absorption would not be interrupted; an increased production
of bleaching powder, on account of a diminished waste of the gas; also the
✓ production of a better quality of bleaching powder, as there would be greater
facilities for purifying the gas and a less injurious effect on the health of the
workmen employed on the process, by diminishing the escape of the chlorine
gas, which is very hurtful in its effect on the human system.