IMPROVEMENTS IN THE MANUFACTURE OF INCANDESCING CONDUCTORS FOR ELECTRIC LAMPS
Year: 1882

page_text: LETTERS PATENT to Thomas John Handford of 42 Southampton Buildings in
ft
the County of Middlesex Patent Agent for an Invention of IMPROVEMENTS
IN THE MANUFACTURE OF INCANDESCING CONDUCTORS FOR ELECTRIC LAMPS."
A communication to him from abroad by Thomas Alva Edison of Menlo Park
in the State of New Jersey. United States of America.
PROVISIONAL SPECIFICATION left by the said Thomas John Handford at the
Office of the Commissioners of Patents on the 19th August 1882.
THOMAS JOHN HANDFORD of 42 Southampton Buildings in the County of
Middlesex, Patent Agent, "IMPROVEMENTS IN THE MANUFACTURE OF INCANDESCING
CONDUCTORS FOR ELECTRIC LAMPS," A communication to me from abroad by
Thomas Alva Edison of Menlo Park, in the State of New Jersey, United States of
America.
The present Invention relates to new materials and processes, and methods for
manufacturing the flexible carbon filaments of incandescing electric lamps, having
a specially high resistance.
According to one mode of carrying out this Invention, there is employed a
carbohydrate such as pure unstructural cellulose, or some compound thereof, which
is formed into filaments and carbonized, or first carbonized and then made into
filaments.
The cellulose or compound of cellulose is dissolved by a suitable solvent and
formed into sheets or membranes, by allowing it to flow upon plates and there
drying it. The filaments with enlarged ends are cut or punched from the sheets or
membranes thus formed which are placed between sheets of paper or metal for the
purpose, and the filaments are then carbonized by heat under strain and pressure,
or the sheets or membranes may be first carbonized and the filaments punched or
cut from the carbonized sheets.
Or the cellulose or compound of cellulose, may be dissolved and allowed to
harden in sheets or otherwise into a mass more or less solid, and may be then

page_text: subjected to heat and pressure and forced through dies to form a fine filament,
which is cut into proper lengths, and carbonized by heat under strain, and pressure.
Before carbonization the enlarged ends may be formed by softening the ends of
the filament by a solvent, and attaching pieces of the softened material thereto, or
the ends of the filament when softened may be doubled upon themselves or
otherwise enlarged, without adding extra material the shortening of the filament
being provided for in cutting.
Or the hardened dissolved cellulose or compound of cellulose may be forced
through dies under heat and pressure, and formed into sheets from which the
filaments are punched before or after carbonization.
In order to overcome the tendency to warp and assume a tortuous shape in
drying, the material may be dried under strain or pressure, or both strain and
pressure may be employed.
With a view to ensuring a definite and uniform thickness of the filaments the
material after being dried in sheets may be pressed between plates of polished
steel, or glass, or other suitable material with or without the aid of heat applied
to one or both of such plates to soften the material.
The filaments are then punched, cut, or shaved from the sheets, before or after
carbonization.
After the sheets are pressed they may be scraped, if they are not absolutely
accurate, by passing them through scraping or shaving dies.
.
For the material a pure instructural cellulose may be used, and can be dissolved
in cuprammonic hydrate; or any compound of cellulose may be employed such as
trinitrocellulose, which may be dissolved or made plastic by a suitable solvent as
ethylic acetate, alcohol and ether, alcohol and camphor, acetone, nitro-benzole,
aniline, or glacial acetic acid.
A drying oil, such as linseed oil may be added in any of the methods before
described, to increase the flexibility of the filaments produced.
Or the flexible carbon filaments of specifically high resistance, may be produced,
by carbonizing an oxidized drying oil, alone, or a mixture of the same with any
other carbonizable material, or materials.
The drying oil or mixture thereof is formed into a tough flexible sheet or
membrane by drying or baking.
The filaments with enlarged ends are punched or cut from this sheet and then
carbonized by heat under strain and pressure, or the sheet may be first carbonized,
and the filaments punched or cut from it after carbonization.
Instead of first forming the drying oil or mixture of the same into sheets, it may
be moulded directly into filaments or run out into a long filament and cut into
proper lengths and provided with enlarged ends before carbonization.
Any drying oil may be used such as linseed, cotton seed, poppy seed, or nut seed,
oil, and this may be used alone or mixed with any other carbonizable material
For this purpose hydrocarbon may be used, preferably one which decomposes
without melting, such as ditolyl, or vegetable, or mineral rezins, carbohydrate, or
albuminoid substances may be employed to mix with the drying oil.
In order to form the drying oil or mixture thereof into sheets, thin polished
metallic plates may be coated with it in the form of a liquid as free as possible from
gritty and other foreign substances
The plates are then dried or baked until the coating forms a tough flexible sheet
or membrane. The metallic plates are then eaten away by an acid leaving the
sheets of oxidized drying oil, or mixture thereof free and intact.
The filaments with enlarged ends are punched or cut from these sheets, and are
carbonized by heat under strain and pressure.
Or the sheets may be first carbonized and the filaments punched from them after
carbonization.
Plates of other material than metal, which is capable of being dissolved by a
substance not attacking the oxidized drying oil, or mixture thereof, may be used to
received the drying oil or mixture thereof. Glass or mica plates can be used for the

page_text: purpose, and be dissolved by hydro-fluoric acid, or plates of gelatine may be used
and be dissolved by water.
The drying oil or mixture thereof in a solid or semi-solid state may be forced out
through dies under heat and pressure, or pressure alone, in the form of a long
filament or a thin sheet which is dried or baked.
The long filament may be cut into proper lengths, and provided with enlarged
ends, before carbonization, while the filaments of proper shape and size may be
punched or cut from the sheets before or after carbonization.
Or in lieu of the materials before mentioned gluten or a mixture thereof with
starch or other material may be used for the production of the flexible carbon
filaments of specifically high resistance.
The gluten is obtained by removing the starch from the flour of cereals, but a
part or all the starch may be allowed to remain mixed with the gluten. A dough
or paste is formed of the gluten, or gluten, and starch, with the minimum amount of
water, and the dough is then pressed out on polished surfaces into sheets of uniform
thickness. Filaments of the desired shape with enlarged ends are punched from
the dough, and are dried after which they are carbonized by heat under strain and
pressure.
Or the dough is forced by pressure from a chamber through an orifice in the
shape of a long filament and is cut into proper lengths. Extra pieces of dough are
put on the ends of the cut filaments to form the enlarged clamping ends, when the
filaments are bent into proper shape, and dried after which they are carbonized by
heat under strain and pressure.
The filaments made in either way described may be dried under strain, or strain
and pressure to preserve their shape.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Thomas John Handford in the Great Seal Patent Office on the
. 17th February 1883.
"
THOMAS JOHN HANDFORD of 42 Southampton Buildings in the County of
Middlesex Patent Agent "IMPROVEMENTS IN THE MANUFACTURE OF INCANDESCING
CONDUCTORS FOR ELECTRIC LAMPS A communication to me from abroad by
Thomas Alva Edison of Menlo Park in the State of New Jersey United States of
America
The said invention relates to the manufacture of the flexible carbon filaments of
incandescing electric lamps having a specifically high resistance.
According to one mode of carrying out the said invention the flexible carbon
filaments of specifically high resistance are produced by carbonizing an oxidized
drying-oil, used alone, or a mixture of the same with any other carbonizable
material or materials.
The drying oil or mixture thereof is formed into a tough, flexible sheet or
membrane by drying or baking. The filaments with enlarged ends are punched or
cut from this sheet and then carbonized by heat under strain and pressure. or the
sheet may be first carbonized and the filaments punched or cut from it after
carbonization.
Instead of first forming the drying-oil or mixture of the same into sheets, it may
be moulded directly into filaments or run out into a long filament and cut into
proper lengths and provided with enlarged ends before carbonization.
Any drying-oil may be used such as linseed, cotton-seed, poppy-seed, or nut-oil,
and this may be used alone or mixed with any other carbonizable material. For
this purpose hydrocarbon may be used preferably one which decomposes without
melting, such as ditolyl, or vegetable or mineral resins, carbohydrates, or albuminoid
substances may be employed to mix with the drying-oil
In order to form the drying-oil or mixture thereof into sheets, thin polished
metallic plates may be coated with it in the form of a liquid as free as possible
from gritty and other foreign substances. The plates are then dried or baked until
the coating forms a tough flexible sheet or membrane. The metallic plates are
then eaten away by an acid leaving the sheets of oxidized drying-oil, or mixture
thereof free and intact.
Plates of other material than metal which is capable of being dissolved by a
substance not attacking the oxidized drying-oil, or mixture thereof, may be used to
receive the drying-oil or mixture thereof. Glass or mica plates can be used for the
purpose, and be dissolved by hydro-fluoric acid, or plates of gelatine may be used
and be dissolved by water.
The drying-oil or mixture thereof in a solid or semi-solid state may be forced
out through dies under heat and pressure or pressure alone, in the form of a long
filament or a thin sheet which is dried or baked In the case of the material being
produced in the form of a long filament the latter may be cut into proper lengths
and provided with enlarged ends before carbonization; but when the material is
made into sheets, the filaments of proper shape and size may be punched or cut
from the sheet before or after carbonization.
According to another mode of carrying out the said Invention gluten or a
mixture thereof with starch or other material is used for the production of the
flexible carbon filaments of specifically high resistance
The gluten is obtained by removing the starch from the flour of cereals but a
part or all of the starch may be allowed to remain mixed with the ġluten. A dough

page_text: or paste is formed of the gluten or gluten and starch, with the minimum amount of
water, and the dough is then pressed out on polished surfaces into sheets of uniform
thickness.
Filaments of the desired shape with enlarged ends are punched from the dough
and are dried, after which they are carbonized by heat under strain and pressure.
Or the dough is forced by prossure from a chamber through an orifice in the shape
of a long filament and is cut into proper lengths. Extra pieces of dough are put
on the ends of the cut filaments to form the enlarged clamping ends, when the
filaments are bent into proper shape and dried after which they are carbonized by
heat under strain and pressure.
The filaments made in either way described may be dried under strain or strain
and pressure to preserve their shape.
Having now described and particularly ascertained the nature of the said
Invention and the manner in which the same is or may be used or carried into
effect I would observe in conclusion that what I consider to be novel and original
and therefore claim as the invention secured to me by the herein before in part
recited Letters Patent is:-
First: The manufacture of flexible carbon filaments for the incandescing
conductors of electric lamps, from carbonized oxidized drying-oil or a mixture
theroof with other carbonizable material or materials, by processes or methods,
substantially as hereinbefore described.
Second: The manufacture of flexible carbon filaments for the incandescing
conductors of electric lamps, from carbonized gluten, or a mixture thereof with
other materials, substantially as herein before described.
In witness whereof I the said Thomas John Handford have hereunto set
my hand and seal this seventeenth day of February in the year of Our
Lord one thousand eight hundred and eighty three.
HWD