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

page_text: LETTERS PATENT to William Robert Lake, of the firm of Haseltine, Lake
& Co, Patent Agents, Southampton Buildings, London for an Invention of
"IMPROVEMENTS IN THE MANUFACTURE OF CARBON CONDUCTORS
FOR
"
ELECTRIC LAMPS A communication to him from abroad by Edward Weston,
of Newark Now Lonsov Tinited States of Amorinn
"
PROVISIONAL SPECIFICATION left by the said William Robert Lake at
the Office of the Commissioners of Patents on the 19th September 1882.
WILLIAM ROBERT LAKE, of the firm of Haseltine, Lake and Co., Patent Agents,
Southampton Buildings, London, "IMPROVEMENTS IN THE MANUFACTURE OF
CARBON CONDUCTORS FOR ELECTRIC LAMPS [A communication to him from
abroad by Edward Weston, of Newark, New Jersey, United States of America.]
Carbon conductors for incandescent lamps, have heretofore been made from
substances or bodies which may be considered as belonging to one or the other of
two classes or groups, viz:-Fibrous substances, such as paper, wood, textile fabrics,
and the like; and non-fibrous or inorganic substances such as retort-carbon, carbon'
formed by electrical deposition, graphite, and the like; either singly or mixed with
amorphous compounds, or bodies, such as asphalt, sugar, syrup and the like.
The fibrous class possesses certain advantages which have conduced to its more.
general use.
Carbons made from fibrous substances are flexible, of relatively high resistance,
and can be readily cut and shaped from the raw material and then carbonized.
On the other hand, the fibrous or cellular structure of the material impairs and>
reduces the density of the carbon; this density is apt to be unequal in different
parts of the same carbon, and the carbon does not possess uniform resistance.
Substances of the non-fibrous class are, as a rule, difficult to handle in the
manufacture of carbons, particularly those intended for the conductors of incan-
descent lamps. The carbon made therefrom is brittle, possessing little or no
flexibility, and the amorphous forms of these substances produce soft porous carbon,
which is practically unfitted for use in incandescent lamps.

page_text: The object of this Invention is to produce a carbon conductor, adapted
particularly for incandescent electric lamps, which shall be open to none of the
above objections; which shall possess flexibility in a high degree, and which shall
be dense, solid, and of even resistance throughout.
To this end, there must be employed a structureless or amorphous and homo-
geneous substance, but this substance inust be of such a nature, that it will, unlike
other amorphous bodies, whose use has been heretofore essayed, preserve practically
unimpaired its uniform density and solidity, without appreciable change, so far as
concerns this characteristic in the arrangement or disposition of its component
elements.
Those conditions are realized in a substance or compound, that can be produced
readily and inexpensively from cellulose, such as is easily obtainable in the form
of cotton waste, linen, paper and the like, and which may be termed non-fibrous, or
amorphous cellulose.
If cellulose, that is to say, cotton, cotton waste, linen or paper, be subjected to
the action of a mixture of nitric and sulphuric acid, the result is a substance, which,
though fibrous, and possessing in some other respects, nearly the same physical
qualities as the pure cellulose, differs radically from it, being explosive, and burning
without appreciable residue. This substance is commonly known as pyroxyline,
gun-cotton, or nitro-cellulose.
By dissolving this with a mixture of ether and alcohol, collodion is produced.
By treating it with various other solvents, such as nitro-benzol, naphtha, camphor;
and other well known solvents, the substance known as celluloid is produced.
Both collodion and celluloid may be formed in thin sheets; and dried, but so long
as. the characteristics of the nitro-cellulose remain, they are both unfit for the
production of carbons for the reason that they burn without residue. In order,
therefore, to render them suitable for my purpose, I de-oxidise them, so to speak,
or in other words, I treat them with such chemical agents as will deprive them of
their nitrous qualities, and bring them back to the chemical condition of cellulose.
Among such reducing agents may be mentioned ammonium sulphide, protochloride
of iron, sulphate of iron, and others.
The sheets of collodion or .celluloid, when exposed to the action of these or
similar reducing agents, are brought back to their original chemical condition, but
in many other respects present the physical appearance of celluloid. They become
transparent, very tenacious and, flexible, and carbonize slightly less readily than
ordinary cellulose. From these I cut or stamp the conducting strips in the usual
manner. After being cut and shaped they are carbonized in the same manner as
heretofore practised in the manufacture of carbon conductors, and the process is
then, complete, and the carbon is finished and ready for use without further
treatment.
;
The carbon presents a very highly polished and lustrous appearance; it is.
extremely flexible and elastic, much more so than any form of carbon known to
me, and is tough and not so liable to break when subjected to sudden jar or shock
its specific resistance is relatively much higher than other kinds of carbon generally
used, so that I am enabled, under the same conditions, to use a larger or broader'
carbon strip.
-
Under the microscope it differs from the carbons in the fact. that it is structure-
less, and amorphous, being free from the fibrous structure of ordinary incandescent,
carbons, and also from the nodulous appearance of the carbons formed by electro-
deposition. I have described. what I delieve to be the best manner of carrying my
Invention into effect, but I do not desire to be understood as confining myself
strictly to the particular substance hereinbefore specified, from which to make the
cai bon, nor to the specific method of producing that substance.

page_text: :
2
SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said William Robert Lake in the Great Seal Patent Office on the
19th March 1883.
=
WILLIAM ROBERT LAKE, of the firm of Haseltine, Lake, & Co, Patent Agents,
Southampton Buildings, London, "IMPROVEMENTS IN THE MANUFACTURE OF
CARBON CONDUCTORS FOR ELECTRIC-LAMPS" a communication to me from abroad
by Edward Weston, of Newark, New Jersey, United States of America
Carbon conductors for incandescent electric lamps have heretofore been made
from substances which may be considered as belonging to one or the other of two
classes or groups, viz. fibrous substances, such as paper, wood, textile fabrics, and
the like; and non-fibrous or inorganic substances such as retort carbon, carbon
formed by electrical deposition, graphite and the like; either singly or mixed with
amorphous compounds or bodies, such as asphalt, sugar, syrup and the like.
The fibrous class possesses certain advantages which have conduced to its more
general use for the above named purpose.
Conductors made from fibrous substances are flexible, of relatively high resistance,
and can be readily cut and shaped from the raw material and then carbonized, but
the fibrous or cellular structure of the material impairs and reduces the density of
the carbon, and this density is, in many instances, unequal in different parts of the.
conductor, which, therefore, does not offer uniform resistance to the passage of the
current.
Substances of the non-fibrous class are, as a rule, difficult to handle in the
manufacture of carbons, or conductors, particularly those intended for incandescent
lamps. The carbon made therefrom is brittle, possessing little or no flexibility, and
the amorphous forms of these substances produce soft porous carbon, which is
practically unfitted for use in incandescent lamps..
The object of this invention is to produce a carbon conductor adapted
particularly for incandescent electric lamps, which conductor will be free from the
above objections, will possess flexibility in a high degree, and will be dense, solid,
and of even or uniform resistance throughout.
For this purpose it is necessary to employ an amorphous and homogeneous
substance, but this substance must. be of such a nature, that it will, unlike other
amorphous bodies, the use of which has been heretofore attempted, preserve
practically unimpaired its uniform density and solidity, without appreciable change,
so far as concerns this characteristic, in the arrangement or disposition of its
component elements.
These conditions are realized in a substance or compound which can be produced
readily and inexpensively from cellulose, such as is easily obtainable in the form
of cotton waste, linen, paper and the like, and which may be termed non-fibrous, or
amorphous cellulose.
Inasmuch, however, as this substance possesses, in a marked degree, all the
qualities which fit it for the production of carbon conductors for incandescent
lamps, as hereinbefore specified, and as I deem it to be the substance best adapted
for that purpose, I shall, in describing the manner in which the said Invention can
practically be carried into effect, also describe the best manner known to me of
producing the aforesaid non-fibrous or amorphous cellulose.
If cellulose, that is to say, cotton, cotton waste, linen or paper, be subjected to
the action of a mixture of nitric and sulphuric acids, the result is a substance
which, though fibrous and possessing in some other respects nearly the same
physical qualities as the pure cellulose, differs radically from it, being explosive, and
burning without appreciable residue. This substance is commonly known as
pyroxyline, gun cotton, or nitro-cellulose.

page_text: By dissolving this substance with a mixture of ether and alcohol, collodion is
produced. By treating it with various other well known solvents, such as nitro-
benzol, naphtha, or camphor, the substance known as celluloid is produced. Both
collodion and celluloid may be formed in thin sheets and dried, but, so long as the
characteristics of the nitro-cellulose remain, they are both unfit for the production
of electric lighting carbons or conductors, for the reason that they burn without
residue. In order, therefore, to render them suitable for my purpose, I de-oxidize
them, or in other words, I treat them with such chemical agents as will deprive
them of their nitrous qualities and bring them back to the chemical condition of
cellulose. Among such reducing agents may be mentioned ammonium sulphide,
protochloride of iron, and sulphate of iron.
The sheets of collodion or celluloid, when exposed to the action of these or
similar reducing agents, are brought back to their original chemical condition, but
in many other respects present the physical appearance of celluloid. Tliey become
transparent, very tenaceous and flexible, and carbonize rather less readily than
ordinary cellulose. From these substances I cut or stamp the conducting strips or
pieces in the usual manner. After the strips or pieces are cut and shaped they are
carbonized in the same manner as heretofore practised in the manufacture of carbon
conductors; the process is then complete and the carbon is finished and ready for
use without further treatment.
The carbon manufactured in this manner presents a very highly polished and
lustrous appearance, it is extremely flexible and elastic, and is tough, and not liable
to break easily; its specific resistance is relatively much higher than that of other
kinds of carbon generally used for electric lighting, so that I am enabled under
the same conditions to use a larger or broader carbon strip. Under the microscope
it differs from other carbons in the fact that it is amorphous, being free from the
fibrous structure of ordinary "incandescent" carbons, and also from the nodulous
appearance of the carbons formed by electro-deposition.
Having thus fully described the said Invention as communicated to me by my
foreign correspondent, and the manner of performing the same, I wish it understood
that I do not confine myself strictly to the specific method of producing the
substance from which to make the carbon, but I claim;
First. A carbon conductor for an electric lamp, made of carbonized non-fibrous
or amorphous cellulose, substantially as herein-before set forth.
Second. The process of manufacturing carbon conductors for incandescent lamps,
which process consists in first converting cellulose into celluloid or collodion, then
treating it with reducing or de-oxidizing agents to convert it into non-fibrous or
amorphous and homogeneous cellulose, and finally forming therefrom the con-
ducting strips, and carbonizing the same, substantially as hereinbefore set forth
In witness whereof I the said William Robert Lake have hereunto set my
hand and seal this Seventeenth day of March in the year of our Lord One
thousand eight hundred and eighty three.