IMPROVEMENTS IN THE MANUFACTURE OF GLASS
Year: 1863

page_text: PROVISIONAL SPECIFICATION left by Tony Petitjean at the Office of
the Commissioners of Patents, with his Petition, on the 15th June
1863.
1, TONY PETITJEAN, of Geneva, Switzerland, Chemist, do hereby declare the
nature of the Invention for "IMPROVEMENTS IN THE MANUFACTURE OF GLASS," to
be as follows:-
My Invention consists in using glass cylinders (in French manchons) as
made by glass blowers to obtain spread window glass, but without cracking
them up along one side as is the practice. I expose glass cylinders at a brisk
red heat by hanging them upon a frame in a horizontal position, another
frame of the same description being placed inside the glass cylinder, and
lodging at the bottom of it in a position parallel with the top one. Those
frames ought not to be entirely in metal, for whatever the metal used might
be it cannot be expected to remain true a long time; besides, for large pieces
metal frames would be too heavy. I prepare for this purpose a kind of
graphite composed of anthracite in fine powder and a metallic solution;- I
also use the kind of carbon found in gas retorts. I then employ one of those
kinds of carbon to prepare the above-mentioned frames, which resist the heat
and are very appropriate for the purpose. The glass cylinder thus laid upon
one frame and bearing the second one is exposed to a red heat which softens
the glass. The frame underneath is carried down by its own weight and
changes the glass cylinder in two plane surfaces, ending at the top and bottom
by two small curves caused by the thickness of the frame. The glass, after

page_text: being annealed, is cut with a diamond, and I thus obtain two fine specimens
of glass, perfectly plane, and having the transparency and the high polish of
crown glass. After this operation the glass cylinder is put into a spreading
furnace, where it soon expands and forms two sheets of glass, the breadth of
which is about one and a half times the diameter of the cylinder employed.
It might be then objected against my spreading process, that only narrow
pieces can be obtained by it, but the glass cylinder can be regularly and inde-
finitely elongated at the expense of its thickness, according to the length of
time it is exposed in the spreading oven. Then by limiting the time of the
operation to the required size, I can give any size to the breadth of my plates.
The glass blower has only to blow the glass thicker than in the ordinary
process.
My spreading furnace is composed of three principal parts. The spreading
one always divides in even number of similar compartments, four, six, or eight,
as may be required; each of them forms, by itself, a spreading oven, in the front
of which is a working orifice. The upper part, in immediate connection with
the spreading ovens, is a transverse gallery to receive plates of glass when
spread, and destined to work them in the manner required. The other part
consists of two longitudinal galleries, one opposite the other, for the cooling
and annealing of the glass. All the motions required for the working of my
process are performed by means of a peculiar and appropriate mechanism.
The kiln is kept continually working. The construction of masonry and some
mechanical arrangements insure the constant parallelism of the frames when
at work.