IMPROVEMENTS IN THE MAnufacture of BLEACHING POWDER
Year: 1871

page_text: LETTERS PATENT to John Knowles Leather, of St. Helen's in the
County of Lancaster, Manufacturing Chemist, for the Invention
of "IMPROVEMENTS IN THE MAnufacture of BLEACHING POWDER.”
Scaled the 24th November 1871, and dated the 1st September 1871.
PROVISIONAL SPECIFICATION left by the said John Knowles Leather
at the Office of the Commissioners of Patents, with his Petition,
on the 1st September 1871.
I, JOHN KNOWLES LEATHER, of St. Helen's, in the County of
Lancaster, Manufacturing Ohemist, do hereby declare the nature of
the said Invention for "IMPROVEMENTS IN THE MANUFACTURE OF BLEACHING
POWDER," to be as follows:-
My Invention consists essentially in causing a current of chlorine gas,
preferably diluted, to hold lime in mechanical suspension for a sufficient
length of time to ensure absorption of the chlorine by the lime, such
lime being in a finely divided state, such as is ordinarily used in tho
manufacture of bleaching powder.

page_text: In carrying my Invention into practice I allow the limo to fall in a
shower through a tower, and cause a current of chlorine gas to ascend
the said tower at the required speed. The current of chlorine may be
induced or caused by natural draught, or by artificial blowing or
exhaustion. If desired the said current of chlorine gas may be caused
to pass through a series of towers. To prevent solid particles of lime
from being carried away I employ a straining cloth stretched across the
tower, or a passage leading therefrom.
It will be obvious that currents of chlorine, diluted or otherwise, may
be caused to hold the lime in- mechanical suspension otherwise than in
a tower, say by a centrifugal current impelled by a fan or other like
apparatus.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said John Knowles Leather in the Great Seal Patent
Office on the 1st March 1872.
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TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
KNOWLES LEATHER, of St. Helen's, in the County of Lancaster,
Manufacturing Chemist, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent; bearing date the First day of September, in the year
of our Lord One thousand cight hundred and seventy-one, in the thirty-
fifth year of Her reign, did, for Herself, Her heirs and successors, give
and grant, unto me, the said John Knowles Leather, Her special. licenco
that I, the said John Knowles Leather, my executors, administrators,
and assigns, or such others as I, the said John Knowles Leather, my
exccutors, 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 MANUFACTURE OF BLEACHING POWDER," upon the
condition (amongst others) that I, the said John Knowles Leather, my:
exccutors 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

page_text: 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 John Knowles Leather, do hereby
declare the nature of my said Invention, and in what manner the same
is to be performed, to be particularly described and ascertained in and
by the following statement, that is to say :—
My Invention consists essentially in causing a current of chlorine gas,
preferably diluted, to hold lime in mechanical suspension for a sufficient
length of time to cause absorption of the chlorine by the lime, such
lime being in a finely divided state, such as is ordinarily used in the
manufacture of bleaching powder.
In carrying my Invention into practice I allow the lime to fall in a
shower through a tower, and cause a current of chlorine gas to ascend
the said tower at the required speed. The current of chlorine may be
induced or caused by natural draught, or by artificial blowing or
exhaustion. If desired the said current of chlorine gas may be caused
to pass through a series of towers. To prevent solid particles of lime
from being carried away I employ a straining cloth stretched across the
tower, or a passage loading therefrom.
It will be obvious that currents of chlorine, diluted or otherwise, may
be caused to hold the lime in mechanical suspension otherwise than in
a tower, say by a centrifugal current impelled by a fan or other like
apparatus.
That others may readily understand the manner in which my
Invention may be carried into practice I havo appended hereto a Sheet
of Drawings illustrative of a tower fitted with appliances for elevating
the lime to and distributing it at the top, and with a supply passage for
gas near the bottom.
Fig. 1 is a vertical section, and Fig. 2 a view looking on the top.
Like letters are marked on the same parts in both views.
a denotes the tower here shown of brickwork; it may be constructed
of iron or other material. endless chain of elevating buckets for
raising the lime to the hopper c. The lime should be in a uniformly
fine stato of division, such as is used in the production of bleaching

page_text: powder by the ordinary process. d is a revolving radial armed feed
driven from the top shaft of the elevators; the speed at which dis
caused to rotate will determine the amount of lime delivered on to the
shoot e, and allowed to fall therefrom into the distributing sieve f, which
latter is suspended by slings g, and caused to partake of a sifting motion
by a tappet arm / secured on the revolving shaft i driven by bevel gear
from the elevator top shaft. The tappet arm h during each revolution
comes into contact with a pin or piece j secured to the distributing
sieve f, and so gives the sifting motion necessary to free the lime in an
uniform shower, whence it will fall by gravity to the bottom. k shows:
a curtain of bunting or other woollen cloth or suitable mineral or other
material to prevent fine particles from being carried away by the waste
gases; the curtain may be variously placed, and it is better to leave it
slack so that it can be shaken without removal. An equivalent for the
curtain may be provided by passing the escaping gases through a
settling chamber. The tower is contracted at a¹ by a hopper-shaped
metal piece, and underneath the lower opening a cylinder of open work
or grid is placed. The said cylinder rests in bearings, and is fitted
with a handle led outside the tower, so that should the bleaching powder
which falls on to it tend to bind and prevent the passage of chlorine it
can be rotated, and thereby freed. m is a closing slide; upon withdrawal
of this the bleaching powder will fall through the opening y. A cask
carried on a truck is shown on the Drawings as receiving the bleaching
powder direct.
n shows a flue through which the chlorine is supplied.
The speed at which the chlorine is supplied will be determined by its
purity or strength. If mixed with atmospheric air in considerable
quantity, or otherwise diluted, the speed will be greater than when the
chlorine is of ordinary purity. A speed of from 4 to 6 feet
per second
with chlorine of 30 per cent. strength in a tower of the height shown,
say 50 feet, will answer, that is to say, the lime is held in suspension,
or is sufficiently long in contact with the ascending chlorine for proper
conversion, but it will be evident that considerable variations for
beneficial working may be made. It will also be evident that fans and
other appliances may be used to force or draw the gases through the
tower

page_text: nearly spent gases in one tower, and has been partially converted
through the tower receiving fresh chlorine.
.
Although I have described and shown a tower in which the lime is
fed at the top it will be obvious that the lime may be supplied through
feed openings in the sides of the tower. It will be obvious also that
currents of chlorine may be impelled by a fan or other appliance in a
circular or other course, and caused to hold lime in "suspension until
conversion; but this I do not find so beneficial as leaving the lime to
fall by gravity in a tower.
'
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Having now described the nature of my said Invention and parti-
cularized the same, I claim, causing a current of chlorine, diluted or
otherwise, to hold lime in suspension sufficiently long to react upon the
lime and convert it into bleaching powder; and I also claim the
appliances described.
In witness whereof, I, the said John Knowles Leather, have
hereunto set my hand and seal, the Twenty-eighth day of
February, in the year of our Lord One thousand eight hundred
and seventy-two.
› In the presence of
JAMES SAUNDERS,
Witness.
JOHN KNOWLES LEATHER. (L.s.)