AN IMPROVEMENT IN THE MANUFACTURE OF A BUILDING CEMENT, COMPOSITION, STUCCO, OR PLASTER, BY MEANS OF THE APPLICATION AND COMBINATION OF CERTAIN KNOWN MATERIALS HITHERTO UNUSED (SAVE FOR EXPERI- MENT) FOR THAT PURPOSE
Year: 1821

page_text: TO ALL TO WHOM, THESE PRESENTS SHALL COME, I, ABRAHAM
HENRY CHAMBERS, of Bond Street, in the County of Middlesex, Esquire, send
greeting..
WHEREAS His most Excellent Majesty King George the Fourth did,
by His Letters Patent under the Great Seal of the United Kingdom of
Great Britain and Ireland, bearing date at Westminster, the Fifteenth day
of January, in the first year of His reign, give and grant unto me, the
said Abraham Henry Chambers, my exors, admors, and assigns, His
especial licence, full power, sole privilege and authority, that I, the said
Abraham Henry Chambers, my exors, adiñors, and assigns, during the term.
of years therein mentioned, should and lawfully might make, use, exercise,
and vend, within England, Wales, and the Town of Berwick-upon-Tweed,
my Invention of "AN IMPROVEMENT IN THE MANUFACTURE OF A BUILDING
CEMENT, COMPOSITION, STUCCO, OR PLASTER, BY MEANS OF THE APPLICATION AND
COMBINATION OF CERTAIN KNOWN MATERIALS HITHERTO UNUSED (SAVE FOR EXPERI-
MENT) FOR THAT PURPOSE;" in which said Letters Patent there is contained a
proviso that if I, the said Abraham Henry Chambers, shall not particularly
describe and ascertain the nature of my said Invention, and in what manner
the same is to be performed, by an instrument in writing under my hand
and seal, and cause the same to be inrolled in His Majesty's High Court
of Chancery within six calendar months next and immediately after the date
of the said Letters Patent, that then the said Letters Patent, and all liberties
and advantages whatsoever thereby granted, shall utterly cease, determine,

page_text: and become void, as in and by the same, relation being thereunto had, will
more fully and at large appear.
NOW KNOW YE, that in compriance with the said proviso, I, the said.
Abraham Henry Chambers, do hereby declare that the nature of my said
Invention, and the manner in which the same is to be performed, are parti-
cularly described and ascertained in the following description thereof (that is
to say):-
I do hereby declare that my aforesaid improvement, consists in the use and
employment of certain burnt or vitrified earths or earthly substances and of
certain metallic and other substances which I cause to be ground or other-
wise reduced to powder, and then to be mixed and incorporated with the
lime for the purpose of producing mortar, plaster, stucco; or building cement
by whatsoever name it may be called or distinguished, thus producing a most
perfect and efficient cement from artificial pozzalana. The earthly substances
which I prefer for this purpose are all those kinds of clay or loam that are
capable of becoming vitrified and intensely hard by exposure to a strong fire,
consequently chalk, and all the various limestones and other earths which
become soft, friable, and capable of slacking or falling to pieces when exposed
to heat, are unfit for the purpose aforesaid; but flint or flint stones or pebbles
may be used with advantage, notwithstanding they do break and fly into pieces
when heated. A trial on a small scale will, however, convince any one whether
any particular earth or earthy or stoney matter is proper to be used, which will
be ascertained by exposing it to a very strong heat, when, if it runs into a
slag or vitrifies or becomes excessively hard, it may be used; but if otherwise,
it must be discarded as unfit for the purpose. The proper kind of earth being
thus selected, it must be heated either in the interior of a brick or other kiln,
or in a kiln or furnace formed for the express purpose, and which may be
built either of bricks or formed of earth, with proper vent holes or flues, until
it becomes completely vitrified or reduced to a state of hard black or glassy
slag, which in many cases will be found sufficiently hard to strike fire with
steel. The harder and more vitrified the materials become, the better they
will answer for my aforesaid improvement. The vitrification of some kinds of
earth will likewise be occasionally assisted and improved by mixing refuse or
broken glass, or even sand and wood ashes before it is exposed to the action
of the fire.
I claim likewise the exclusive privilege of appropriating other slags or
vitrified materials which are not produced for the express purpose to my afore-
said improvement, such as those which come from the furnaces of smelting

page_text: houses, glass houses, foundries, steam engines or other boilers, and all mate-
rials reduced to a state of vitrification by intense heat. The whole of the
aforesaid materials, whether produced for the particular purpose, or obtained
from any of the before-mentioned sources, and whether consisting of vitrified
earth, metallic or other vitrified slag from furnaces, or burnt flint or flint
stones, must be bruised, pounded, or ground by any of the usual, accustomed,
and well-known methods, until it is reduced to such a grit as will be con-
venient and necessary for the formation of the particular sort of mortar,
stucco, plaster, or cement which may be required. For this purpose it must
be passed through such wire screens or sieves as will produce the necessary
fineness or quality, and being so separated into different qualities it may be
put up into casks or otherwise preserved for use, and is a most perfect arti-
ficial pozzalana. The manner of using the above material or materials is to
mix it with well-burnt lime instead of the sand usually employed for the form-
ation of mortar, stucco, plaster, or cement, water being added as usual until it
is of the proper consistence to be used; or the artificial pozzalana or above,
materials may be mixed with quicklime completely pulverized, and sent in
casks or other packages ready to be used, with the addition of water only.
In this latter case it will be necessary to keep it from moisture or exposure
to the open air until the time of using it. The proportion of quicklime that
must be added to the above materials will depend entirely upon the goodness
or strength of the lime that is used. In general one measure of good lime
will be sufficient for from three to five measures of the aforesaid materials;
but this must be regulated by the work for which it is intended, and will be
readily ascertained by a little experience.
I hereby further declare, that another part of my said Invention and
improvement consists in the use and appropriation of marble of various
colours and of various-coloured bricks when highly burnt or vitrified and
reduced to fine powder, for the purpose of producing all the variety of colours
and shades, required to imitate stone and highly-polished wood and marble.
And lastly, I claim the exclusive right and privilege of using vitrified earth
and the aforesaid other materials, for the purpose of mixing with lime or
plaster of Paris to cast figures, ornaments, and mouldings of every description.
In witness whereof, I, the said Abraham Henry Chambers, have here-
unto set my hand and seal, this Seventh day of July, in the year of
our Lord One thousand eight hundred and twenty-one.
AB H (L.S.) CHAMBERS.

page_text: AND BE IT REMEMBERED, that on the Seventh day of July, in the
year of our Lord 1821, the aforesaid Abraham Henry Chambers came before
our said Lord the King in His Chancery, and acknowledged the Specification
aforesaid, and all and every thing therein contained and specified, in form
above written. And also the Specification aforesaid was stamped according
to the tenor of the Statute made for that purpose.
. Inrolled the Tenth day of July, in the year of our Lord One
thousand eight hundred and twenty-one.