NEW OR IMPROVED EMERY OR CORUNDUM WHEELS
Year: 1879

page_text: LETTERS PATENT to James Ballantyne Hannay, of Glasgow, in the County of
Lanark, North Britain, for the Invention of "NEW OR IMPROVED EMERY OR
CORUNDUM WHEELS."
Sealed the 1st July 1879, and dated the 4th January 1879.
PROVISIONAL SPECIFICATION left by the said James Ballantyne Hannay at
the Office of the Commissioners of Patents on the 4th January 1879.
JAMES BALLANTYNE HANNAY, of Glasgow, in the County of Lanark, North Britain.
"NEW OR IMPROVED EMERY OR CORUNDUM WHEELS."
This Invention, which relates to new or improved emery or corundum wheels,
consists in binding together the particles of emery or corundum with silicious and
alkaline materials, which when fused unite and form a glass throughout which the
emery or corundum is closely interspersed, and by which the whole is firmly held
together.
Silicious matters suitable for the purposes of this Invention are ground flint and
ordinary glass waste, commonly known as cullet, suitable alkaline matters being
salts of potash, soda, and lime.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said James Ballantyne Hannay in the Great Seal Patent Office on the 4th
July 1879.
JAMES BALLANTYNE HANNAY, of Glasgow, in the County of Lanark, North Britain.
"NEW OR IMPROVED EMERY OR CORUNDUM WHEELS."
My said Invention relates to new or improved emery or corundum wheels, in
which the particles of emery or corundum are mixed with silicious and alkaline
materials, as hereinafter described, so that they unite when fused and treated, as
also hereinafter described, by which the whole is firmly bound together.
And in order that my said Invention may be properly understood I now proceed
more particularly to set forth the system, mode, or manner in or under which the
same is or inay be used or practically carried into effect, that is to say :-
I take silicious material, such as ground flint or sand, and form a fusible vitreous
compound by mixing alkaline material (viz., potash, or soda, or both) therewith in
considerable excess of that employed in ordinary glass making, and melting them
together in any suitable furnace. The proportions of the said alkaline materials aro
from 20 to 35 per centum of the total mixture, the lower percentage being consi-
derably above that used in making ordinary glass, and the higher percentage being
under that used in making soluble glass or silicate of soda. Lime or oxide of lead
may be used in the said compound if desired, but they are not essential. The above
given proportions of alkaline materials refer only to the potash and soda employed.
In place of taking silicious materials and alkaline materials separately, glass or
"cullet" may be employed in the making of this compound, and sufficient potash
or soda added to make up the above per centage of alkaline material. Any propor-
tion of borax under what causes the compound to become soluble may be added to
the compound, and this increases its fusibility, but the vitreous substance so made
is costly. The compound when melted is withdrawn from the furnace and cooled,
and is then ground to powder of such degree of coarseness that it will not pass
through a finer meshed riddle than one whose interstices are 30 to the lineal inch.
With this powdered vitreous compound I mix emery or corundum in such propor-
tion and degree of fineness as will produce a wheel of the kind suitable for the
particular purpose to which it is to be applied; for instance, for an ordinary cutting
wheel, from 60 to 70 parts of emery of the fineness known as No. 1%, to from 40 to
30 parts of the vitreous compound will be found to work well.
The mixed vitreous compound and emery or corundum is or may be formed into
a wheel as follows:-
The mixture is heated in a furnace until partially fused and softened, so that it
will cohere, and then a quantity sufficient for the wheel to be made is removed and
placed in a mould, and sufficient pressure applied to compress it into the mould and
reduce the porous mass to a state of solidity. The wheel thus formed, after slightly
cooling in the mould so that the said wheel will not lose its shape in handling, is
removed from the mould and placed in an annealing furnace, or otherwise allowed
to cool.
In place of forming the wheel as before described, the mixed vitreous matter and
emery or corundum are moistened so as to cause their particles to cohere, and
rammed into a mould; the mould is then removed and sand is substituted. The
wheels lying upon bricks or other supports may be piled in a kiln or furnace and
fired till the materials are thoroughly cemented.
Having now described and particularly ascertained the nature of my said In-
vention, and tho system, mode, or manner in or under which the saine is or may be
used or practically carried into effect, I would observe in conclusion that I am
aware that it has been attempted to employ ordinary glass (that is to say, a vitreous
material containing the ordinary per centage of alkaline matter) for the manufacture

page_text: of emery or corundum wheels, but in the employment of this ordinary glass the
results were very uncertain, and the wheels when produced were very friable and
otherwise objectionable; the essential feature of my Invention and what I therefore
claim as secured to me by the herein-before in part recited Letters Patent is,―
The new or improved emery or corundum wheels herein-before described, that is
to say, emery or corundum wheels produced by the use of a cementing material
consisting of a vitreous compound of silicious and alkaline matters, in which the
alkaline matter is present in a proportion of from 20 to 35 per cent.
In witness whereof, I, the said James Ballantyne Hannay, have hereunto
set my hand and seal, this First day of July, in the year of our Lord
One thousand eight hundred and seventy nine.
JAMES BALLANTYNE HANNAY. (L.S.)