Improvements in and relating to the Manufacture of Material for the Production of Carbon Filaments for Incandescent Electric Lamps and other Articles.
Year: 1887

page_text: Improvements in and relating to the Manufacture of Material for
the Production of Carbon Filaments for Incandescent Electric
Lamps and other Articles.
I WILLIAM ROBERT LAKE of the firm of Haseltine Lake & Co. Patent Agents
Southampton Buildings in the County of Middlesex, do hereby declare the nature of
this invention and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement :-
This invention relates to the manufacture of a material suitable for carbon filaments
for incandescent electric lamps plates for microphones, and ornamental and other
articles as hereinafter set forth.
The main object of the invention is to employ ulmic or similar materials, such as
metagallic acid (acide embelli feronique) or other acids either containing carbon
principles or not.
In carrying out this invention materials in a pasty condition are used in preference,
thus obtaining easily any desired form either by wire drawing or by pressing the paste
into a mould before carbonization.
Amongst ulmic materials, an ulmic acid in a plastic or pasty condition produced
in a manner hereinafter described is employed.
A solution is prepared consisting of 80 grammes of sugar in 100 gr. of distilled
water, this solution is filtered, another 100 gr. of distilled water being added during
the operation and the filtered product is collected in a porcelain receiver. To this
solution about 300 gr. of sulphuric acid is added drop by drop at the rate of about a
drop per second, a spherical funnel fitted with a cock being employed for the purpose,
the solution meanwhile being constantly stirred becomes thick and assumes a dark
nearly opaque red colour. This mixture is then allowed to rest for about 12 hours,
kept covered over, after that, with a spherical funnel as above described 300 to 400 gr.
of distilled water are dropped at the rate of about 80 drops per minute into the
mixture keeping stirring at the same time. Having allowed the mixture to cool it is
poured into a receiver of a capacity of about six litres; the said receiver is filled by
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page_text: adding water a little at a time, after this it is decanted, water being again added
until it is reduced to a density of about 2° Beaumé. The mixture is then filtered
until it attains a sufficient density to be worked by means of an indiarubber roller
upon a piece of glass or upon a polished marble slab so as to render it plastic. This
mass contains air that must be expelled; to do this it is placed in a receiver of a
vertical cylindrical or any other suitable form in which moves a hermetically tight
piston. This receiver is closed at the extremity opposite to the piston by an india-|
rubber plug, and is connected with an air pump.
When the paste is ready it is placed in the cylinder, which is filled about full,
after this the indiarubber plug is placed in position and the air pump set to work,
when this operation is over, by short quick blows the paste is knocked against the
bottom in order to work it up and amalgamate it.
The paste is then in a very plastic condition, and can easily be moulded into articles
of any form. To obtain for example filaments for incandescent electric lamps a small
syringe is employed, or an apparatus similar to that used for manufacturing vermicelli.
Other articles are obtained either by pressing the paste in a mould or by modelling
by hand. The filaments obtained as above described can be cut to any desired length,
and can assume any shape that it is wished to impart to them.
The articles obtained by the above described process are first left to dry at the
ordinary atmospheric temperature in a slightly damp place, they are then placed in
an oven in which they are subjected to a heat of about 100° C.
After being thus dried the articles are placed in crucibles filled. with powdered
charcoal or in furnaces containing an inactive gas to protect them from contact with
the air, and they are brought to a high temperature in a reverberatory furnace to
obtain their complete carbonization.
The filaments that are intended for carbons for incandescent electric lamps are
employed without any other treatment just as they come out of the furnace, but
other articles especially those destined for ornaments can if desired be burnished.
Having now particularly described and ascertained the nature of my said invention
and in what manner the same is to be performed as communicated to me by my
foreign correspondent I declare that what I clain is :-
First. The employment of ulmic or similar substances to produce a material fit
for the fabrication of carbon filaments for incandescent electric lamps, as well as
for the production of other articles in use in science and arts, as above described.
Second. The process employed for obtaining ulmic acid in the form of a paste
capable of being wire drawn or moulded into any desired form with the view of
obtaining articles as already stated, by following all the operations successively
above described and specified.
Dated this 27th day of Sentember 1887
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C.,
Agents for the Applicant.