AN IMPROVED MODE OF MANUFACTURING CEMENT
Year: 1870

page_text: LETTERS PATENT to Henry Young Darracott Scott, of Ealing, in
the County of Middlesex, Lieutenant-Colonel Royal Engineers, for
the Invention of "AN IMPROVED MODE OF MANUFACTURING CEMENT."
Sealed the 30th August 1870, and dated the 26th April 1870.
PROVISIONAL SPECIFICATION left by the said Henry Young Darracott
Scott at the Office of the Commissioners of Patents, with his
Petition, on the 26th April 1870.
I, HENRY YOUNG DARRACOTT SCOTT, of Ealing, in the County of
Middlesex, Lieutenant-Colonel Royal Engineers, do hereby declare the
nature of the said Invention for "AN IMPROVED MODE OF MANUFACTUring
CEMENT,' to be as follows :---
"
The object of this Invention is the manufacture of a cement of good
colour and quality with the use of inexpensive materials.
In carrying out this Invention I bring about the intimate admixture
of lime, clay, and sulphate of lime or other cheap sulphates in the pro-
portion, say, of 67 parts of lime, 30 parts of clay, and 3 parts of sulphate
in every one hundred parts by weight of the compound. I do not
however tie myself to these exact proportions differences of composition

page_text: and of perfection in the admixture often rendering some variation of
them advisable. Morcover the proportions may be varied to some
extent without absolutely vitiating the result. This compound I subject
to calcination and subsequently grind it to a fine powder, after which it
is ready for use.
I sometimes also in lieu of lime use chalk, and in lieu of a sulphate
sulphuric acid, and I employ these ingredients in such proportions
as will produce similar proportions with the above in the calcined
compound.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Henry Young Darracott Scott in the Great Seal
Patent Office on the 26th October 1870.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, HENRY
YOUNG DARRACOTT SCOTT, of Ealing, in the County of Middlesex,.
Lieutenant-Colonel Royal Engineers, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-sixth day of April, in the year
of our Lord One thousand eight hundred and seventy, in the thirty-
third year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto me, the said Henry Young Darracott Scott, Her special
licence that I, the said Henry Young Darracott Scott, my executors,.
administrators, and assigns, or such others as I, the said Henry Young
Darracott Scott, my executors, administrators, and assigns, should at any
time agree with, and no others, from time to time and at all times there-
after 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 "AN IMPROVED MODE OF MANUFACTURING CEMENT,” upon the condition
(amongst others) that I, the said Henry Young Darracott Scott, 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 Henry Young Darracott Scott, 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) :—
The object of this Invention is the manufacture of a cement of good
color and quality from the purer limes or from limestone or the upper
chalk by means of a simple and economical process whereby also a
considerable saving of time is effected as compared with the existing
methods of compounding artificial hydraulic limes and cements.
In carrying out my Invention I employ sixty-seven parts of quicklime,
thirty parts by weight of fine unctuous clay, and three parts of plaster
of Paris or other cheap and soluble or partially soluble sulphate, such as
sulphate of iron, but I do not confine myself to these precise proportions,
which are mentioned merely as those which I consider best adapted to
the object in view. I pulverize these ingredients separately and then
proceed as follows:-I first make a thin milky slip of the three parts of
plaster of Paris together with water in the pan of an edge runner or
ordinary mortar mill, and to this I add by degrees the sixty-seven parts
of quicklime, and by keeping the mill in motion I thoroughly agitate
and mix the whole into a homogeneous fluid paste. I next introduce into
the mill the thirty parts of clay, and continue the mixing until this
compound also is homogeneous throughout. In this operation no more
water should be used than the quantity necessary to take advantage of
the freedom of motion between the particles which the addition of a
small quantity of water will bestow.
In the manufacture of artificial cements as now practised and con-
sisting of compounds of lime or chalk and clay it is at present necessary
(after the incorporation of the ingredients in the presence of a large
quantity of water in a wash mill or similar appliance) to conduct the
mixture into reservoirs or backs of great extent, where it remains for
many weeks so that the solid matters may be deposited from the water.
When the process is completed the supernatant water will be run off
and the solid matter may then be removed and dried upon stoves or
licated flues.
In my improved process I withdraw the compound from the mill
when it is sufficiently mixed, and as only water sufficient to ensure the
proper admixture of the ingredients has been used it will be understood
that the solid matters will be taken from the mill in a pasty state or like

page_text: well mixed mortar. This solid compound is allowed to remain in heaps
until it is stiff enough to be conveniently handled and formed into bricks
or lumps. It is believed that it is owing to the peculiar action of the
sulphate upon the quicklime in the mixture that in a few hours the mass
will commence to set, and will so far stiffen that it may conveniently be
made into bricks or pressed into balls or lumps. The formation into
bricks is accomplished either by hand or by machinery..
For the sake of economy a pug mill may be used, from which the
material is squeezed out in a continuous strip and may be divided into
proper lengths by means of wires or other cutters, but the best results
may be obtained by subjecting the material to heavy pressure. The
bricks or blocks thus formed are then stacked for drying. They are
subsequently burnt in any suitable form of kiln either as bricks are
usually burned, or the lump may be burned as lime is burned. The
temperature of the kiln must be so regulated as to bring the silex in the
clay into the condition in which it can unite freely with the lime, care
being taken that the heat is not too great. The calcined bricks or lumps
can then either be sent out in the brick form, leaving them to be ground
up on the works at the time of use, and mixed with sand and other
materials in a mortar mill, or the bricks or lumps may be pulverized and
sent out in bags or casks in the powdered state and used in the manner
practised with Portland and Roman cements.
<<
When chalk or limestone is used in lieu of lime the proportions of the
ingredients will become seventy-eight parts of chalk, nineteen of clay,
and three of plaster of Paris, or thereabouts, and the only difference in
the mode of procedure will arise from the fact that the mixture of chalk,
clay, and sulphate does not contain within itself any setting properties
which will assist in getting rid of the water. The slip must consequently
be treated in the same way as the slip or "slime" is in Portland cement
manufacture, that is, it is allowed to settle in large reservoirs or backs,"
the top water is drawn off, and when the compound has attained sufficient
consistency to be moved it is spread on ovens to be dried. The dried
mass is then broken up into lumps as is also practised in Portland
cement making, and these lumps are calcined in an ordinary lime or
cement kiln until the whole of the carbonic acid is expelled. The
calcined lumps may then be either sent out without grinding to be
pulverized on the works, or they may be ground as a part of the manu-
facture and the pulverized material be sent out in bags or casks. In

page_text: some cases instead of employing unslaked lime and preventing it from
slaking by the use of sulphate of lime or other sulphate as described I
first slake the lime and then incorporate the slaked lime with the sulphate
and clay in the before-mentioned proportions by any convenient method.
The advantage of this method is the very fine state of division produced
by the slaking of the lime and its comparatively greater chemical
activity as regards the clay which is thus brought about, but it has the
disadvantage of yielding a less dense material with the low degree of
calcination which is required for the expulsion of the water of hydration.
It may, however, sometimes be of advantage to combine these various
methods of procedure and to cause the hydration of a portion only of the
necessary lime, making use of the remainder in the caustic state for the
purpose of setting the mixture; or when chalk or limestone is used I
may introduce a small proportion of quicklime to set the compound as
above described.
In the above description of the process I have stated both in the case
of lime and chalk what I consider to be the best method of proceeding,
but I do not intend to confine myself to the precise quantities of the
several ingredients which I have named, nor to the use of the particular
sulphates specified, for I can with advantage use sulphate of soda,
alum, or even sulphuric acid, which forms a sulphate on coming into
contact with the lime. The alkaline sulphates will be found useful when
there is a deficiency of the bases of such salts in the clay employed.
Insoluble sulphates are however inefficient in their action.
The object of the process is the manufacture of a hydraulic compound
which but for the addition of the sulphate would be considered an
artificial lime, but which with the intimate admixture of the sulphate in
the manner described (before the final calcination) or in the case of chalk
before the expulsion of the carbonic acid becomes what may with more
propriety be termed a cement inasmuch as it is not slaked before being
used, but solidifies its water of hydration after its application in the
work. It is manifest that many variations in the method of procedure
may be introduced without departing from the principles involved in
the operations or processes which I have described, and without being
anything else than equivalent processes, and for all such I claim.
Having now described my Invention, and the manner of carrying the
same into effect, I wish it to be understood that I claim as the Invention
secured to me by Letters Patent as aforesaid, the use in the manufacture

page_text: of cements of sulphate of lime or other suitable sulphate or sulphuric
acid in combination with the other ingredients as above set forth.
I further claim the mode or process herein set forth for effecting the
intimate admixture and consolidation of the ingredients employed in the
manufacture of cement whereby a large quantity of the water usually
employed in the process of mixing the ingredients may be dispensed
with, and a considerable economy of time and labour may be effected.
In witness whereof, I, the said Henry Young Darracott Scott, have
hereunto set my hand and seal, the Eighteenth day of October,
in the year of our Lord One thousand eight hundred and seventy.