IMPROVEMENTS IN THE MANUFACTURE OF HYDRAULIC LIMES AND CEMENTS
Year: 1877

page_text: LETTERS PATENT to Alexander Melville Clark, of 53, Chancery Lane, in the
County of Middlesex, Patent Agent, for the Invention of "IMPROVEMENTS IN
THE MANUFACTURE OF HYDRAULIC LIMES AND CEMENTS." A communication
from abroad by Désiré Michel, of Marseilles, France.
Sealed the 28th May 1878, and dated the 1st December 1877.
PROVISIONAL SPECIFICATION left by the said Alexander Melville Clark at
the Office of the Commissioners of Patents on the 1st December 1877.
ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the County of Middlesex,
Patent Agent. "IMPROVEMENTS IN THE MANUFACTURE OF HYDRAULIC LIMES
AND CEMENTS." [A communication from abroad by Désiré Michel, of Marseilles,
France.]
This Invention relates to improvements in the manufacture of hydraulic limes
and cements.
The improved process of manufacture consists in subjecting the materials to bo
converted into hydraulic limes or cements to a special treatment with acids.
Without entering into a description of the transformations or complex chemical
re-actions which may be produced in the treatment of cements with acids, I would
more particularly draw attention to the remarkable results which may be obtained
by the employment of this improved process, allowing as it does of the manufacture
in a certain and economical manner from any description of raw materials, having
hydraulic properties of cements and limes which are perfectly hydraulic, will set
with mathematical regularity, are absolutely inalterable both before and after use,
and of a uniform composition such as can only be obtained with difficulty in
cements prepared by the ordinary processes.
The following is the improved method of making hydraulic limes and cements:-
Instead of keeping down the heat of the kiln in which the materials aro calcined
within certain limits, I so raise it as to overburn the products. In certain cases
I extract, if necessary, the first lime which is in excess, and I then subject the
nodules and underburnt remainder to the action of a bath of dilute hydrochloric
acid. The proportion of acid will of course vary with the amount of lime contained
in the under-burnt portion and nodules, but it would not exceed on an average
3 or 4 per cent. The proportion should, in all cases, be determined with accuracy

page_text: by a preliminary test and a previous analysis of the raw materials. Hydrochloric
acid is employed by preference, but I reserve the right of using any other acid
which will yield analogous results The nodules and under-burnt portion are
allowed to effervesce in the acid baths until quite cooled, and are then dried in a
furnace until fit for grinding in the ordinary manner.
I would have it understood that in manufacturing limes and cements according
to this Invention, I may apply the acid treatment either before or after burning,
and either in the dry or humid way, whether such acid be used in the form of a
vapor or gas in the concentrated form or in solution in water, and whether such
acid be made to act separately on the minerals or elements of which the limes and
cements are composed, or upon the raw material itself.
The Invention thus consists in the application and employment of acids in the
manufacture of hydraulic cements and limes whereby the latter may be over-buint
without injury, and the under-burnt portion and nodules (which in the ordinary
process of manufacture are wasted and cause considerable loss) are utilized for the
manufacture of hydraulic limes and cements of first quality
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Alexander Melville Clark in the Great Seal Patent Office on the
31st May 1878.
ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the County of Middlesex,
Patent Agent. "IMPROVEMENTS IN THE MANUFACTURE OF HYDRAULIC LIMES
AND CEMENTS." A communication from abroad by Désiré Michel, of Marseilles,
France.
This Invention relates to improvements in the manufacture of bydraulic limes
and cements.
The improved process of manufacture consists in subjecting the raw materials to
be converted into hydraulic limes or cements to a special treatment with acids.
Without entering into a description of the transformations or complex chemical
re-actions which may be produced in the treatment of cements with acids, I would
more particularly draw attention to the remarkable results which may be obtained
by the employment of this improved process, allowing as it does of the manufacture
in a certain and economical manner from any description of raw materials, having
hydraulic properties of cements and limes which are perfectly hydraulic, will set
with almost mathematical regularity, are absolutely inalterable both before and
after use, and of a uniform composition, such as can only be obtained with difficulty
in cements prepared by the ordinary processes.
The following is the improved method of making hydraulic limes and cements :-
Instead of keeping down the heat of the kiln in which the materials are calcined
within certain limits, I so raise it as to over-burp the products. In certain cases I
extract, if necessary, the first lime which is in excess, and I then subject the nodules

page_text: and under-burnt remainder to the action of a bath of dilute hydrochloric acid. The
proportion of acid will of course vary with the amount of lime contained in the
under-burnt portion and nodules, but it could not exceed on an average 3 or 4 per
cent. The proportion should, in all cases, be determined with accuracy by a pre-
liminary test and a previous analysis of the raw materials. Hydrochloric acid is
employed by preference, but I reserve the right of using any other acid which will
yield analogous results. The nodules and under-burnt portion are allowed to
effervesce in the acid baths until quite cooled, and are then dried in a furnace until
fit for grinding in the ordinary manner.
I would have it understood that in manufacturing limes and cements, according
to this Invention, I may apply the acid treatment either before or after burning
and either in the dry or humid way, whether such acid be used in the form of a
vapor or gas, in the concentrated form or in solution in water, and whether such
acid be made to act separately on the minerals or elements of which the limes and
cements are composed, or upon the raw material itself
By means of this Invention hydraulic cements and limes may be over-burnt
without injury, the under-burnt portion and nodules (which in the ordinary process
of manufacture are wasted and cause .considerable loss) being utilised for the
manufacturo of hydraulic limes and coments of first quality.
Having described the nature of the said Invention, and the manner of performing
the same, I declare that what I claim as the Invention to be protected by the
herein-before in part recited Letters Patent is, the application and employment of
acids in the manufacture of hydraulic limes and cements, as and for the purpose
herein specified.
In witness whereof, I, the said Alexander Melville Clark, have hereunto set
my hand and seal, thus Thirty-first day of May, in the year of our Lord One
thousand eight hundred and seventy-eight.