Earthenware.
Year: 1887

page_text: Date of Application, 14th Apr., 1887.
Specification Accepted, 17th May, 1887.
of Earthenware.
I, FERDINAND WALLBRECHT of the town of Hannover, Germany, Gentleman, do
hereby declare the nature of my invention and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement:-
My invention relates to improvements in the manufacture of bricks, tiles and all
kinds of earthenware and consists chiefly in treating clay and other raw materials for
making bricks tiles and other ware.
The process enables the goods or ware to be burnt in wet condition without the said
treatment in any way prejudicing the burning of the same in dry condition. According
to my invention the customary raw materials are mixed with salts before the forming
and burning. The salts specially suited for employment in my said process are
chlorate of soda, chlorate of potash, further, the sulphuric, carbonic and nitric salts of
the alkalies or the pure oxides of the same. The mixing of the raw materials with
such salts is carried out either by saturating the said raw material with an aqueous
solution of the salts or mixing the wet or dry materials with the salts in powdered or
natural granular form.
This mixture of clay and salts is formed and either burnt direct in wet condition or
previously air dried. During the burning process the water which is chemically
combined and mechanically mixed with the raw material is converted into hydrogen
and oxygen at a comparatively low temperature in consequence of the presence of the
alkali in the same. The hydrogen is either burnt, thus producing a considerable
saving in fuel as the temperature is considerably increased, (as is the case with a smithy
fire) or,
it forms a compound with the chlorine of the chlorate of the alkalies and
escapes as muriatic acid vapors. The oxygen combines with the metallic alkalies to
oxides of alkali which act as smelting medium.
If the mixture of the raw materials with the salts is effected in wet condition, as
for instance in making bricks which are formed in hand moulds, the bricks etc. will bo
burnt in remarkably short time, much easier and the form will be retained much better
than with the customary process. In consequence of the moisture in the same, i.e.

page_text: the decomposition of the water into hydrogen and the oxide of alkali formed by the
absorbed oxygen, the process is facilitated. But, even when the materials are mixed
dry with the powdered or natural salts and subjected to high pressure, the same
advantages are attained, as a fritting takes place in comparatively short time although
weaker than when water or steam is present.
The water chemically combined with the clay and also the water in the salt crystals
and especially in salts crystallised out of the saline solutions, becomes free at about
300 degrees Centigrade is decomposed by the heat in burning, and the hydrogen and
oxygen utilized in the manner before specified.
A mixture of moist clay and coarse grain salt can also be employed with like
advantage.
The mixture of the salts and the process ensuing during the burning, cause a readier
solution of the silicic acid and facilitate the operation of burning. Experiments have
shown that when simple quartz sand, moistened with a saturated solution of salt, is
subjected to the heat of a common stove, the silica in the sand will be converted into
soluble silicic acid. In manufacturing bricks according to my process, the fritting
will ensue so readily that no deformation of the form will occur and any lime that
may be present will be prevented from causing any disadvantageous effect as the same,
as well as the silicic clay or silica, is converted into a compound entirely insoluble in
water.
Firm, well burnt weather proof goods can be produced according to this process
even from the worst kind of raw material in shorter time than heretofore. By mixing
the raw materials with salts, artificial porcelain clay can be produced.
Having now particularly described and ascertained the nature of my said invention
and in what manner the same is to be performed, I declare that what I claim is :-
In the manufacture of bricks, tiles and other earthenware, mixing the wet or dry
raw material before the forming and burning, either with an aqueous solution of the
carbonate, sulphate or nitrate salts of the alkalies, their chlorides or the oxides of
the same, or with the powdered or granular salts or oxides of the said alkalies and
burning the same either in wet or air dried condition, substantially as and for the
purpose herein set forth.
FREDERIC PRINCE,
1, Quality Court, Chancery Lane, W.C.,
Agent for Applicant.