AN IMPROVEMENT IN THE MANUFACTURE OF HYDRAULIC CEMENTS
Year: 1873

page_text: LETTERS PATENT to Alexander Bennett McGrigor, of Glasgow,. in
the County of Lanark, North Britain, Solicitor, for the Invention
of "AN IMPROVEMENT IN THE MANUFACTURE OF HYDRAULIC CEMENTS."
-A communication from abroad by James Moeller Robertson, of
Melbourne in the Colony of Victoria
Architect
"
Scaled the 7th October 1873, and dated the 19th June 1873.
PROVISIONAL SPECIFICATION left by the said Alexander Bennett
McGrigor at the Office of the Commissioners of Patents, with his
Petition, on the 19th June 1873.
I, ALEXANDER BENNETT MCGRIGOR, of Glasgow, in the County of
Lanark, North Britain, Solicitor, do hereby declare the nature of the
said Invention for "AN IMPROVEMENT IN THE MANUFACTURE OF HYDRAULIC
CEMENTS," to be as follows, that is to
say:
-
This said Invention has for its object the making of a water or
hydraulic cement of the class sometimes termed "Portland" cement or
mortar, usually made of complicated preparations of ground and

page_text: powdered carbonate of lime and chalks, calcined and mixed with sand
and broken bricks, river silts, clays, and earth containing silicate of
alumina and of lime, many of which require sifting, washing, and
precipitating to separate their impurities or detrimental substances from
them, all which makes the manufacture of these cements difficult and
uncertain in quality and results compared with the use of simple
natural ingredients or bases forming the essentials of this my new mode
and means of making this cement.
And the nature of this Invention consists in the manufacture of a
powerful hydraulic cement from certain infusorial limestones belonging
to the oolitic and other geological periods, many of which are well
known, and often used for freestone, mixed in powder, with any of the
nearest obtainable basalts of the various basaltic formations and periods,
both as simply found in nature, and which I have found by examination
contain the necessary substances for making a good water cement with-
out the separation of substances thereto or from, as is usual with the
substances and processes heretofore employed. These two natural
substances or bases, which do not materially vary in their composition,
are mixed together in certain proportions, found simply by trial
depending mainly on the nature of the basalt at hand and used. The
mixture is then calcined and powdered in a usual manner, when it is
ready for mixing and use.
The petitioner does not claim to have invented any new mode or
means of calcining, grinding, or mixing, but what he believes and claims
as new is the making of a water or hydraulic cement from a simple
mixture of any two of the before mentioned natural substances or
infusorial limestones with basalt, substantially as described.

page_text: And the nature of this Invention consists in the manufacture of a
powerful hydraulic cement from certain infusorial limestones belonging
to the oolitic and other geological periods, many of which are well
known and often used for freestone, mixed in powder with any of the
nearest obtainable basalts of the various basaltic formations and periods, 5
both as simply found in nature, and which I have (discovered or) found
by examination contain the necessary constituents for making a good
water cement without the addition or separation of substances thereto
or from, as is usual with the substances or processes heretofore
employed. These two natural substances or bases are mixed together 1
in certain proportions, found simply by trial, according to the quality of
the two ingredients and the kind of cement required. The mixture is
then calcined and powdered in a usual manner, when it is ready
for use.
And in order that the nature of my said Invention, and the manner 1
of performing the same may be fully and properly understood, I shall
now proceed to describe the best modes and means I am at present aware
of for making the said new or improved cement in accordance with this
Invention.
I find that infusorial limestone or any other sufficiently pure limestone 2
in combination with basalt or other plutonic or trappean rock, either in
the rock or decomposed as soil, produces a most powerful hydraulic
cement without the addition of any other matter, and without separating
any of their natural ingredients, but the said soil is only of value to my
Invention when it contains all the constituents of the original basalt or 2
other rock from which it is derived, and I claim the use of no other soils
or clays.
The only materials I use for the manufacture of my hydraulic cement
arc infusorial limestone, or any other sufficiently pure limestone,, and
basalt, or other plutonic or trappean rock, either in the rock or decom-
posed, and in the form of such soil as abovo described. I grind these
materials to powder, and after mixing them I form the material (or
*slip," out of which the new cement is subsequently to be made) with
the addition of sufficient water to make it plastic into uniform lumps of
about the size of an ordinary brick, which size may be smaller or larger, a
but must be regulated according to the size of the kiln to be used; the

page_text: proportion between the limestone and basalt or other plutonic or trappean
rock is dependent on the quality of limestone and the basalt used, and
specially on the class of cement desired to be produced..
For quick setting cement I use two of limestone to one of basalt, or
other plutonic or trappean rock; and for slow setting cement I go as
high as four of limestone to one of basalt, or other plutonic or trappean
rock, and the character of the cement may be varied in any degree
between these two extremes.
The raw materials may be ground by any of the well-known mechanical
mcans, but it is important that the materials should be so fine as to
pass through a sieve of sixty-five meshes to the lineal inch. The
materials must be thoroughly mixed before being formed into bricks or
lumps.
After the lumps are thoroughly dry they are burnt in any ordinary
shaped or conical kiln adopted in lime burning, or it might be in the
improved construction of kilns adopted and patented by Frederick
Joseph Bramwell, Number 657, dated 13th March 1871, but whatever
construction of furnace or kiln may be adopted the fuel or gaseous
products of combustion employed must be in direct contact with the
said raw cement bricks; the bricks are then ground into powder, which
forms the hydraulic cement, the subject of my Invention.
Having thus described the nature of my said Invention, and the
manner of carrying the same into effect, I wish it to be distinctly
understood that I do not confine myself particularly to the mere details
of manufacture herein-before described, and I would also have it under-
stood that I do not claim any of the processes of grinding or calcination
hercin-before described, nor the use of infusorial or other limestone or
of basalt, or other plutonic or trappean rock, either in the rock, or
decomposed as soil as above mentioned, as ingredients in this manu-
facture of hydraulic cement when used in combination with other
substances or earths, but what I claim is, the use of infusorial
limestone or any other sufficiently pure limestone in combination with
basalt or other plutonic or trappean rock, either in the rock or decomposed
as soil, but only in the form of the said soil when it contains all the
constituents of the original rock from which it is derived, and without
any other material in the manufacture of hydraulic cement, all in the

page_text: thereof.
In witness whereof, I, the said Alexander Bennett McGrigor, have
hereunto set my hand and seal, this Seventeenth day of De-
cember, in the year of our Lord One thousand eight hundred and
seventy-three.
Witness,
W. R. M. THOMSON,
Patent Agent,
Glasgow.
ALEX. B. McGRIGOR. (L.S.)