IMPROVEMENTS IN THE MANUFACTURE OF FILAMENTS FOR INCANDESCENT OR GLOW LAMPS
Year: 1884

page_text: I, JAMES SWINBURNE of 41 Manor Road, Brockley, in the county of Kent
Electrician do hereby declare the nature of iny invention for IMPROVEMENTS IN
THE MANUFACTURE OF FILAMENTS FOR INCANDESCENT OR GLOW LAMPS, to be as
follows:-
My invention is a method of making carbon filaments.
I use cotton, paper, or any other suitable form of cellulose, and act on it with
very strong_nitric acid. This converts it wholly or partially into a jelly-like
substance. I wash this and heat it with a suitable reducing agent and so convert
it into a less combustible substance of somewhat similar physical appearance. Thus
a suitable cotton or linen thread may be passed continuously through strong nitric
acid; then through water; and may then be boiled in a solution of potassium or
ammonium sulphide.
If paper be used, a similar treatment is advisable, the filaments being cut at any
convenient stage in the process. Instead of nitric acid I may use acetic anhydride
or any other agent giving an analogous action with cellulose. Instead of cellulose
as the basis, others of the same group of substances may be used. Sheets of the
gelatinous substance sometimes called xyloidin may be made from starch, for
example. After reduction, the filaments may be carbonised and enclosed in bulbs
in the usual ways.
Dated this Twenty-eighth day of February 1884.

page_text: I, JAMES SWINBURNE of 41 Manor Road Brockley in the County of Kent,
Electrician, do hereby declare the nature of my. invention for IMPROVEMENTS IN
THE MANUFACTURE OF FILAMENTS FOR INCANDESCENT OR GLOW LAMPS and in
what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement :-
My invention is a method of making carbon filaments.
I use cotton paper or any other suitable form of cellulose, & act on it with very
strong nitric acid. This converts it wholly or partially into a jelly like substance.
I wash this and heat it with a suitable reducing agent & so convert it into a less
combustible substance of somewhat similar physical appearance. Thus a suitable
cotton or linen thread may be passed continuously through strong nitric acid, then
through water; and may then be boiled in a solution of Potassium or Ammonium
sulphide. If paper be used a similar treatment is advisable, the filaments being
cut at any convenient stage in the process. ."
The
A process of making filaments by nitrating cellulose & then reducing it is already
known; but sulphuric acid.is mixed with the nitric acid, & the fibres of the
cellulose are not coagulated into a homogeneous or partly homogeneous mass.
nitrated compound has therefore to be dissolved to get rid of the fibrous structure.
According to my invention the fibres are sufficiently agglomerated to do without
any further solvents. Soft knitting or crotchet cottons are the most suitable. If
paper is used it should be porous & not sized. It may be cut into very narrow
strips; and these may be bent round into a loop, or horse-shoe shaped filaments
may be punched out of flat sheets.
Having now particularly described & ascertained the nature of my said
invention.& in what manner the same is to be performed I declare that what
I.claim is.
Coagulating the fibres of cellulose by means of Nitric Acid to make Incandescent
Electric Lamp filaments.
Dated this 28th day of November 1801