IMPROVEMENTS IN THE MANUFACTURE OF CARBONS FOR INCANDESCENT ELECTRIC LAMPS "
Year: 1883

page_text: LETTERS PATENT to Joseph Wilson Swan of Bromley in the County of Kent
Chemist for an Invention of "IMPROVEMENTS IN THE MANUFACTURE OF
CARBONS FOR INCANDESCENT ELECTRIC LAMPS
"
PROVISIONAL SPECIFICATION left by the said Joseph Wilson Swan at the
Office of the Commissioners of Patents on the 31st December 1883.
.
JOSEPH WILSON SWAN, of Bromley in the County of Kent, Chemist,
"IMPROVEMENTS IN THE MANUFACTURE OF CARBONS FOR INCANDESCENT ELECTRIO
LAMPS
"
It is necessary for obtaining the greatest efficiency in electrical lamps in which
light is produced by the incandescence of a carbon filament that the filament
should be of a homogeneous and solid texture and that its section should be
uniform in size.
Hitherto there has been experienced great difficulty in producing thin carbon
filaments of a perfectly uniform sectional size, and at the same time homogeneous
and solid in texture.
My Invention has for its object the production of carbon filaments possessing
these qualities and the removal of the difficulties which have hitherto stood in the
way of their production.
According to my said Invention I take a carbonisable material in a plastic or
semi-liquid state and I squeeze or press it through a hole or die so as to form a
thread or threads of equal substance and of any required length and also of any
required form in transverse section-The material I may employ in carrying out
my Invention is a solution of Nitrocellulose in Acetic Acid, with or without the
addition of other well known solvents of Nitrocellulose and with or without other
carbonisable material than nitrocellulose. I do not limit myself to this particular
solution of Nitrocellulose nor to the use of a Nitrocellulose solution at all as the
carbonisable material, for my process of forming carbonisable thread by squeezing a
carbon liquid or paste through a die is applicable to any suitable carbonisable

page_text: material in a plastic, liquid, or semi-liquid condition, for example nitro-glucose
rendered plastic by heat may be employed-In employing an Acetic Acid Solution of
Nitrocellulose I project the filament as it issues from the die into water or other
liquid which has the effect of instantly setting or giving, coherence to the issuing
thread.
When the thread has been formed in the manner described I treat it with a
solution of Hydro-sulphate of Ammonia or other equivalent deoxidising agent until
it is no longer in a condition to burn explosively, and I then dry and shape it
into the forms in (which it is to be used in the lamps and I carbonize it in any
suitable manner.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Joseph Wilson Swan in the Patent Office on the 30th June 1884.
JOSEPH WILSON SWAN of Bromley in the County of Kent Chemist
"IMPROVEMENTS IN THE MANUFACTURE OF CARBONS FOR INCANDESCENT ELECTRIC
LAMPS "
It is necessary for obtaining the greatest efficiency in Electrical Lamps in which
light is produced by the incandesence of a Carbon filament or thread that the
filament or thread should be of a homogeneous and solid texture and that its
section should be uniform in size.
Hitherto great difficulty has been experienced in producing thin Carbon filaments
or threads of a perfectly uniform sectional size and at the same time homogeneous
and solid in texture.
My Invention has for its object the production of Carbon filaments or threads
possessing these qualities and the removal of the difficulties which have hitherto
stood in the way of their manufacture.
According to my said Invention I take a Carbonisable material of the nature or
kind hereinafter mentioned in a plastic or semi-liquid state, and I squeeze or
press it through a hole or holes or die or dies or jet or jets so as to form a filament
or thread or filaments or threads of any required length and of equal substance
throughout its or their length and also of any required form in transverse section.
The material I employ in carrying out my Invention is a solution of Nitro-
cellulose in Acetic Acid or other solvent. Other Carbonizable material may be
combined with the Nitrocellulose or the Nitrocellulose solution may be used alone
or I may employ nitro-glucose rendered plastic by heat.
I project the filament or filaments of thread or threads as it or they issues or
issue from the die or dies or their equivalents into a liquid such as Alcohol (of say
from seventy to eighty per cent of Spirit) or into other liquid which has the effect
of setting or giving coherence to the issuing thread.
The accompanying drawing represents an apparatus which may be used in
carrying my Invention into effect. It is given as an example and as a means of
making the Invention perfectly understood but I do not limit myself to the use of
this particular form of apparatus. Figure 1 is an elevation and figure 2 is a
vertical section. A represents a strong metallic Cylinder constituting the body of
the apparatus-It is closed by a covering piece B held down by the cap piece C
which is screwed down so as to compress the packing D firmly to give a tight
joint. E is a pipe from the reservoir of an air compressing pump secured in the
nozzle piece F through which the passage G leads to the interior of the part A
which is lined with a glass Cylinder H terminating in a nipple piece or jet h
having a fine orifice therethrough and passing through the bottom of the part A.
I is a lining of plaster of Paris or other suitable material to keep the glass
Cylinder H in place. J is a screw closing plug or tap by which the passage G can
be closed whilst the air is being compressed by the pump attached to the pipe E.
The apparatus may be supported by a stand as at K so that the outlet orifice
through the nozzle or jet h is situated over a vessel L into which the material is
passed as it issues from the said orifice or jet. The Carbonizable material in a
plastic or semi liquid state is put into the receiver A which is firmly closed. The
cap J is closed and air is pumped into the reservoir connected with the pump
until it has attained a sufficient pressure when the tap J is opened and the
carbonizable material is forced slowly through the orifice in the nozzle or jet h
from which it may pass into the vessel L containing a liquid for the purpose
herein before described.

page_text: When the thread or filament has been formed in the manner described I treat it
with a solution of Hydro Sulphate of Ammonia or other equivalent deoxidizing
Agent until it is no longer in a condition to burn explosively and I then wash it
with water and dry and shape it into the forms in which it is to be used in the
Lamps and I carbonize the material thus obtained in any suitable manner or I may
carbonize the filament in a straight form and afterwards bend it if it be required
to be in a bent form.
Having now described and particularly ascertained the nature of my 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 hereinbefore in part
recited Letters Patent is :-
First—Manufacturing Carbons for incandescent electric Lamps by forcing
material of the nature hereinbefore described in a plastic or semi liquid state
through a hole or holes die or dies or jet or jets and subsequently deoxidizing
and Carbonizing the resulting filament or filaments substantially as herein before
described.
Second. Manufacturing Carbons for Incandescent electric lamps by forcing a
mixture or solution of Nitrocellulose in Acetic Acid (or other solvent) through a
hole or holes die or dies or jet or jets and subsequently deoxidizing and
Carbonizing the resulting filament or filaments substantially as hereiubefore
described.
-
Third Manufacturing a thread or filament applicable to the production of
Carbon filaments for incandescent electric Lamps by forcing a solution of Nitro-
cellulose in Acetic Acid or other solvent through a hole or holes die or dies or jet
or jets into a liquid capable of causing the "setting" of the thread or filament as it
issues from the jet or jets substantially as hereinbefore described.
Fourth. Manufacturing Carbons for incandescent electric Lamps by forcing a
mixture or solution of Nitrocellulose in Acetic Acid (or other solvent) or the
equivalent thereof as herein before stated through a hole or boles die or dies or
jet or jets and into Alcohol or other suitable liquid for causing the setting
coagulation or coherence of the issuing filament or filaments and subsequently
treating the said filament or filaments with a deoxidizing Agent and then
carbonizing the said filament or filaments substantially as herein before described.
In witness whereof I the said Joseph Wilson Swan have to this my Specification
set my hand and seal this twenty seventh day of June One thousand eight
hundred and eighty four.