IMPROVEMENTS IN CRUCIBLES, MUFFLES AND OTHER REFRACTORY APPARATUS
Year: 1885

page_text: Apparatus.
I FARNHAM MAXWELL LYTE of Cotford,. Oakhill Road Putney in the County of
Surrey, Analytical Chemist, do hereby declare the nature of my said invention
for "IMPROVEMENTS IN CRUCIBLES, MUFFLES AND OTHER REFRACTORY APPARATUS
to be as follows:-
"
My Invention consists in the manufacture of crucibles, muffles, and close furnaces
of all kinds where the heat has to be applied exteriorly, of magnesia in a more or
less pure state suitably agglomerated alone or mixed if desirable with powdered
plumbago, retort carbon, or other suitable form of carbon. The magnesia may be
agglomerated in any of the usual manners, but a method I have found particularly
successful is as follows:-
Magnesite (natural magnesia carbonate) or other magnesia or its carbonate is
strongly calcined. By this means the earth contracts considerably, if a carbonate
it loses carbonic anliydride, and if in the solid form becomes filled with minute
cracks and becomes much less easily soluble in acids. It is then finely ground and the
powder so formed mixed or not with the above nained materials and the necessary
quantity of wet magnesium hydroxide and water is made up into a thick paste of
a consistence suitable for moulding and fashioned by any of the usual methods into
the required forms and then burnt in the usual way. The principal precaution to
be observed is that care should be taken never to heat strongly a vessel so composed
of magnesia or magnesia and carbon in contact with ordinary bricks, firebricks,
silica, or any clinker or mineral residue of the combustion of ordinary fuel. The
powdered calcined magnesia may also be agglomerated by means of a solution of
any suitable magnesia salt, as the nitrate or chloride for instance. Crucibles,
muffles, &, so constructed should only be heated by astatki, water gas, or other
gaseous fuel so as not to bring them into contact with the mineral residue of the
combustion.
The above method of manufacture may of course be applied to that of other
refractory articles, such as tubes, gas furnaces &

page_text: The advantages of these crucibles and other refractory apparatus are as
follows
1st They are not subject to become porous even at the highest temperatures.
2nd Alkaline fluxes which injure or destroy rapidly other refractory materials are
completely inert with respect to this-Even lead oxide which rapidly fuses and
destroys other crucibles can be kept melted for any length of time in crucibles
made of this material 3rd It will stand in a most wonderful way the greatest
and most rapid alternations of temperature without cracking 4th When properly
made the material is very solid and can be manipulated to any ordinary degree
with tongs or otherwise without danger or fracture.

page_text: I, FARNHAM MAXWELL LYTE of Cotford, Oakhill Road, Putney in the County
of Surrey, Analytical Chemist do hereby declare the nature of this 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 consists in the manufacture, in the manner hereinafter described,
of crucibles, muffles, gas furnaces, tuyeres, tubes, and other similar refractory
apparatus, of magnesia.
The magnesia is to be calcined and prepared, as hereafter described, and may be
agglomerated either with, water only, or preferably with the addition of the
hydroxide, or of an acid or salt of magnesia as hereafter mentioned, which has
the effect of accelerating the "setting" and solidification, and of facilitating the
throwing and moulding of the material.
The method of preparing and agglomerating the magnesia is as follows;-
Magnesite, (natural magnesia carbonate) or other magnesia (or its carbonate) is
calcined at a strong white or crucible heat, by which means this earth contracts
considerably. In order, however, to obtain sufficient contraction, I find it preferable
to submit the magnesia to repeated calcinations say three in all-the material being
ground and sifted or disintegrated, so as to shift the particles, after the first
calcination, and sifted before each subsequent calcination. In this way, all the
particles are more perfectly and rapidly affected by the heat. The highly calcined
and powdered magnesia may be agglomerated with water alone as above mentioned,
or with about six to ten per cent of magnesium hydroxide, of the "heavy" kind,
and a suitable quantity of water or with a small proportion of less strongly burnt
magnesia, say ten to fifteen per cent, and a suitable quantity of water; the highly
calcined magnesia so agglomerated being in either case brought to a consistency
suitable for moulding or throwing. The article so fashioned is then to be fired, if
necessary for the purpose to which it is to be applied. In lieu of magnesium
hydroxide, I may use a solution of any suitable magnesian salt, such as for
instance the nitrate or chloride (but not the sulphate) or any of the corresponding
acids.
In order to render the magnesia, agglomerated in any of the ways above specified,
more refractory I may incorporate therewith powdered plumbago, retort carbon, or
other suitable form of carbon.
Crucibles, muffles, etc, so constructed should be heated by astatki, water-gas, or
other gaseous fuel in preference to coal or other solid combustible.
In the case of apparatus in which porosity is a necessary quality, as, for instance,
gas furnaces where great non conduction of heat is required, I add saw-dust, flour,
or other organic matter to the calcined and powdered magnesia.
The absorbent nature of the magnesia would render it useless for the manufacture
of crucibles, scorifiers, and other apparatus of a like nature when used for metals

page_text: producing fusible oxides, unless the apparatus were coated with a glaze, such as is
sometimes applied to highly refractory articles.
Having now particularly described and ascertained the nature of the said
Invention, and in what manner the same is to be performed; I declare that
what I claim is ;-
1. The manufacture of crucibles, muffles, gas furnaces tuyeres, tubes, and other
similar refractory apparatus of magnesia which has been calcined and ground as
specified until sufficient contraction has been obtained to avoid subsequent cracking
of the manufactured article.
2. The manufacture of refractory apparatus of the kind mentioned in Claim 1 of
a mixture of magnesia which has been highly calcined as herein specified, and of
lightly calcined or "soft burnt" magnesia, substantially as specified.
3. In the manufacture of refractory apparatus of the kind mentioned in Claim 1
from magnesia which has been bighly calcined as herein specified, the employment
of "heavy." magnesium hydroxide or of a magnesian salt, (such as the nitrate or
ichloride) or its corresponding acid, for agglomerating the magnesia as specified.;
4. In the manufacture of refractory apparatus of the kind mentioned in Claim 1,
the addition to the highly calcined magnesia of any suitable form of carbon for the
purpose
of increasing the refractory nature of the apparatus, as specified.
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