IMPROVEMENTS IN MANUFACTURING MILLSTONES
Year: 1855

page_text: LETTERS PATENT to Pierre Antoine Henry Parant, Ceramic Materials
and China Ware Manufacturer, in Limoges, France, for the Invention of
PROVISIONAL SPECIFICATION left by the said Pierre Antoine Henry
Parant at the Office of the Commissioners of Patents, with his Petition,
on the 20th October 1855.
I, PIERRE ANTOINE HENRY PARANT, Ceramic Materials and China Ware
Manufacturer, in Limoges, France, do hereby declare the nature of the
said Invention for "IMPROVEMENTS IN MANUFACTURING MILLSTONES "
follows:-
The improvements consist in manufacturing artificial millstones with any
suitable vitrifiable materials.
A mixture being prepared with kaolin, or any other of the fusible materials
used for the manufacture of china, hardware, or glass, I mix with this com-
position fragments of wood, coals, seeds, or other combustible materials, their
size and nature, as well as their relative position in the artificial millstones,
being regulated according to the kind of work for which, the stones are
intended. The mixture is then placed in suitable moulds, shaped as sectors of
the stone which is to be manufactured, and subsequently baked. The moulds
are used, however, only for the purpose of giving the sectors the required form;

page_text: the sectors are then withdrawn therefrom and introduced into the oven, in
which they are to undergo the baking process. The sectors are then put
together so as to form a circular stone, and are united or bound together by
iron hoops, as usual. While baking, the combustible fragments burn out,
and the sectors remain porous, or full of small recesses, as is the case with
the natural millstones;-but-the-pores are regulated in the mixture, so that
the largest may be nearest the centre, and the smallest gradually towards the
circumference.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Pierre Antoine Henry Parant in the Great Seal Patent
Office on the 19th April 1856.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, PIERRE
ANTOINE HENRY PARANT, Ceramic Materials and China Ware Manufacturer,
in Limoges, France, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twentieth day of October, in the year of our Lord
One thousand eight hundred and fifty-five, in the nineteenth year of Her reign,
did, for Herself, Her heirs and successors, give and grant unto me, the said
Pierre Antoine Henry Parant, Her special licence that I, the said Pierre
Antoine Henry Parant, my executors, administrators, and assigns, or such
others as I; the said Pierre Antoine Henry Parant, my executors,, .adminis-
trators, 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 In-
vention for "IMPROVEMENTS IN MANUFACTURING OF MILLSTONES," upon the.con
dition (amongst others) that I; the said Pierre Antoine Henry. Parant,.by' an
instrument in writing under my hand and seal, 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.
NOW KNOW..YE, that I, the said. Pierre Antoine Henry. Parant, 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

page_text: Millstones, especially those used for grinding cereals, are generally made of
natural quartz or silex, the quality and disposition of the constituent parts
of which have inequalities and defects, which frequently interfere with the
regular performance of the work to be done.
The artificial millstones manufactured according to my plan obviate. these
defects to a considerable extent, and they are made as follows:-
I prepare a mixture with pulverised kaolin, or any other fusible or vitrifiable
material of similar. nature, as for china, hardware, or glass manufacturing;
the mixture being prepared as just said, a certain proportion of wood, charcoal,
grains, or any other, such combustible materials in small fragments are blended
with it. The proper size, quantity, and nature of the said combustible materials,
and the situation which these materials should occupy, in the composition of
the artificial millstone; are regulated by the kind of work which it is intended
to perform: In the usual process of grinding, the materials to be ground
being admitted under the flying stone through its centre, are gradually divided
and conveyed to the circumference; whence they issue completely. ground and
pulverised; wherefore the pores of millstones should be coarser and more
distant from each other at the central. portion of the millstone than at its
circumference, where they should, however, progressively become smaller and
closer, as represented in Fig. 3 of the annexed Drawing. It is necessary for
the same reasons to prepare the ceramic materials of several degrees or
numbers of fineness, so, that proper mixtures may be made in order to secure
a proper space between the holes or pores, the larger being nearer the centre,
and the smaller ones on the circumference. When the several ceramic
mixtures are ready, I take a cast iron or plaster mould; Figure 2; similar to
one of the sections of the complete grinding stone, Figure 1, which consists of
12 sections, more or less, according to the work to be performed; the internal
sides of the mould corresponding to the size of the required section, its depth
varying according to the thickness which I may wish to give to the millstone.
The division of the millstone in 12 sections, more or less, far from interfering
with the proper working of the face, is,, on the contrary, very advantageous, since
it gives a perpendicular or square edge to the flutings or reedings icüt in the
stone, by which the grinding and the passage of the ground materials is greatly
facilitated. The mould having been filled up with the ceramic or vitrifiable
materials, I take out the block thus formed, suitably prepared, as mentioned
above, as soon as it has acquired a sufficient firmness or consistence, and by
repeating the operation I eventually obtain the required number of sections of
millstones similar to those seen Figure 3; the blocks are then allowed to dry,
and when they have acquired a suitable degree of dessication, I place them in

page_text: a furnace, and expose them therein to a degree of heat sufficient to melt the
ceramic materials. During the burning process, the particles or fragments of
'wood or other combustible materials contained in the blocks are burnt out,
leaving in the blocks holes more or less considerable in size, according to the
'dimensions of the fragments of the combustible materials employed, which
empty spaces-or-holes-answer the purpose of the sharp cavities which the natural
millstones exhibit; but in natural millstones these sharp cavities or recesses
are either too few or too numerous; too wide or too small, too far apart or too
near each other; sometimes large places of à perfectly solid nature; and
without any cavities being found in such stones, which circumstance of course
renders them unfit for use.
By my Invention, on the contrary, the sharp or working cavities or recesses
are produced at will, and in such a manner as to obtain a stone by which
perfect grinding is attained. When the blocks or sectional parts of the mill-
stones have been thus suitably shaped, prepared, and burnt, I take the number
of them required to form a millstone; I adjust them together by putting a thin
layer of plaster between each block; I then bind them all together by means
of one or more iron hoops, and the stone is then fit for use.
In witness whereof, I, the said Pierre Antoine Henry Parant, have
hereunto set my hand and seal, this Eighth day of April, One
thousand eight hundred and fifty-six.
Signed, sealed, and delivered by the above-
named Pierre Antoine Henry Parant, in
the presence of
CHARLES HENRY,
P. A. H. PARANT. (L.S.)
Ancien Secrétaire en Chef de la Mairie,
de Limoges, en Retraite.