IMPROVEMENTS IN THE MANU- FACTURE OF CEMENTS
Year: 1875

page_text: LETTERS PATENT to John Bowing, of Woolwich, in the County of
Kent, Chemist, for the Invention of "IMPROVEMENTS IN THE MANU-
FACTURE OF CEMENTS."
Sealed the 23rd December 1875, and dated the 5th July 1875.
PROVISIONAL SPECIFICATION left by the, said John Bowing at the
Office of the Commissioners of Patents, with his Petition, on the
5th July 1875.
I, JOHN BOWING, of Woolwich, in the County of Kent, Chemist,
do hereby declare the nature of the said Invention for "IMPROVEMENTS
IN THE MANUFACTURE OF CEMENTS," to be as follows:-
.
The mixture of water, chalk, and clay (or other such like materials
used in the manufacture of cements), as it leaves the mill or apparatus,
in which it is prepared is termed "slurry." The insoluble portion when
rendered sufficiently dry and fit for heating or burning into cement is
termed "slip."
I convert "slurry" into "slip" by forcing the slurry in or on to
any suitable filtering medium, either by means of pumps, centrifugals,
hydrostatic heads, or other convenient means of exerting and maintaining
a pressure on the "slurry" while in contact with the filtering material,

page_text: vapours or fumes) is removed from the deposited "slip," being held in
solution in the water which escapes by being expelled from the filters.
These bodies are resident in the clay which has pre-eminently the power
of taking up and almost fixing such matters, as is seen by its action in
all soils capable of isolating soluble manurial food for plant life.
The sodic chloride and other salts and soluble matter by the usual
methods evaporated to dryness and left in the " slip," and which are
sources of great inconvenience in the manufacture of cement, of course
by my process also go off in solution with the waste water from the
filter.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said John Bowing in the Great Seal Patent Office
on the 5th January 1876.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
BOWING, of Woolwich, in the County of Kent, Chemist, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Fifth day of July, in the year of
our Lord One thousand eight hundred and seventy-five, in the thirty-
ninth year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto me, the said John Bowing, Her special licence that
I, the said John Bowing, my executors, administrators, and assigns, or
such others as I, the said John Bowing, my executors, 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 CEMENTS," upon the condition (amongst others) that I, the said
John Bowing, my executors 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 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.

page_text: NOW KNOW YE, that I, the said John Bowing, do declare the
nature of my said Invention, and in what manner the same is to be
porformed, to be particularly described and ascertained in and by the
following statement :-
The mixture of water, chalk, and clay (or other such like materials
used in the manufacture of cements), as it leaves the mill or apparatus
in which it is prepared is termed "slurry." The insoluble portion when
rendered sufficiently dry and fit for heating or burning into cement
is termed "slip."
"
,,
I convert "slurry” into " slip" by forcing the slurry" in or on to
any suitable filtering medium, either by means of pumps, centrifugals,
hydrostatic heads, or other convenient means of exerting and maintaining
a pressure on the "slurry" while in contact with the filtering material.
By this action I cause the water to rapidly leave the insoluble matter or
*slip" deposited in or on the filter and itself to pass away through the
substance of the filter and escape.
[
་
By adjustment of the amount and duration of the pressure employed
tho "slip" can be rendered so far dry as to fit it for the succeeding
operation of heating or "burning." Or it may be further dried by a
short exposure to a temperature sufficiently high for the purpose.
I claim that the advantages of this method of preparing "slip" arc,
among others, the cost, time, and space occupied are far less than when
it is prepared by natural subsidence, precipitation, heating, or any other
of the usual existing methods.
"E
But above all I claim that in its mechanical and chemical condition
the "slip" as prepared by my process closely resembles the natural
limestones, and is much superior to the "slip" as at present made. The
water having been rapidly passed from the "slip" causes the particles
of clay and chalk (which mixture may be taken as typical of all cement
slips") to arrange themselves only in the most uniform manner, there
can be no excess of clay in one part of the mass and chalk in another
(as often happens by the action of gravity in slow filtrations or by
subsidence) provided the original mixing in the mill has been properly
conducted. This property secures in the "burning" to the silica,
alumina, and lime molecules, the most perfect means of reacting
upon cach other, and so forming the salts of lime called hydraulic
cements.

page_text: "
The high and uniform density of the " 'slip further aids and
accelerates the "burning
burning" process and lessens the formation of
dust.
In "slip" as usually made great variation is found in the density and
in the amount of residual water, some portions being compact and others
sponge like, some with little more than merely water of composition and
others almost plastic. These slips when heated in the kilns are
irregularly and violently fractured, so that much dust is generated, and
carried off by the blast maintained in the kiln, or it falls and chokes the
draught.
Lastly. I claim for my process that a great reduction of obnoxious
fumes ensues, since a large proportion of the organic and other matters
volatile at the high temperature of the kilns (the chief cause of these
vapours or fumes) is removed from the deposited "slip," being held in
solution in the water which escapes by being expelled from the filters.
These bodies are resident in the clay which has preeminently the
power of taking up and almost fixing such matters, as is seen by its
action in all soils capable of isolating soluble manurial food for plant
life.
The sodic chloride and other salts and soluble matter by the usual
modes evaporated to dryness and left in the “ slip," and which are
sources of great inconvenience in the manufacture of cement, of course
by my process also go off in solution with the waste water from the
filter.
In witness whereof, I, the said John Bowing, have hereunto set
my hand and scal, this Fifth day of January, in the year of
our Land 1976
Signed, sealed, and delivered by
the said John Bowing in the
presence of
JNO. ANDREWS,
32, Essex St.,
Sol.
JNO. BOWING. (L.S.)