Year: 1886

page_text: I JOHN GARRETT TONGUE of the firm of Tongue and Birkbeck Patent Agents of
34 Southampton Buildings in the County of Middlesex Fellow of the Institute
of Patent Agents (a communication from J. Kirby, Engineer of Namur, Belgium)
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 has for its object a new or improved manufacture of hard rods of
carbon of cylindrical square or prismatic form solid or hollow and called crayons-
bougies or electric carbons, such as in the manufacture of plates, sheets, cylinders
and other forms of carbon used in electric piles, for telegraphic, telephonic, electric
light, and other electrical purposes.
In tar, there exists a very fine powder, which is held in suspension. This
powder is essentially 90 to 99 per cent, pure carbon; it is therefore the best
substance required for the manufacture of electric crayons, carbons, plates, and
other forms in carbon on account of its purity.
For this purpose according to this invention the said carbon is extracted by
means of a solvent, known as tar-naphtha which yields 90% on distilling at
between 150 and 190 degrees Centigrade, or with any other suitable solvent such
as creosote, heavy oil or light oil or even bisulphide of carbon.
By mixing two parts of one of these solvents with one of tar a black pasty
compound is obtained. This compound is then poured into a linen or other bag in
order to separate by filtration the tarry matter contained therein from the carbon.
The former passes through the filtering bag whilst the black paste consisting of
carbon is retained in the bag which is then pressed; and this black paste is
afterwards carbonised in a retort. The product is a coke or carbon, and is the

page_text: material from which the crayons, plates and other carbon forms for electrical
purposes are made.
The method of manufacture is as follows:-
1st The tar is liquified by mixing one part of the latter with two parts of the
solvent which boils at between 150 and 190 degrees Centigrade and yields 90%
naphtha. This solvent is used between these two degrees on account of its
volatility which is rather high and also because of its low price and for facility
in filtration.
This mixture is then poured into a linen or other suitable filtering bag where
the tar matters filter through and a black paste is deposited in the bag.
2nd This paste is submitted to hydraulic pressure in order that all tarry matters
may be extracted as completely as possible.
3rd After having undergone this pressure the paste takes the form of a cake
which is carbonised in suitable retorts of hard or fire bricks till no more gas comes
off. After a little cooling the black coke or carbon is removed from the retort.
4th This carbon then passes into a suitable crusher or grinder from which it is
sifted by means of a sieve in order to obtain an impalpable powder.
5th This powder is then moistened with a little tar in order to form a hard paste
which is placed in a cylinder where it is subjected to great pressure, being
compressed, by a piston which forces it out of the cylinder through an opening,
causing it to assume a cylindrical or other homogeneous form, either solid or
hollow.
6th This paste on coming out of the cylinder is cut into lengths and is then dried
in a drying apparatus, having a steam jacket round it, where it remains for seven
or eight days. After this time the pieces thus prepared are placed in a different
form of drying apparatus, which is heated by an open fire. At first the temperature
is very low it is then gradually raised, little by little, for a period of about twelve
days according to the dimensions of the pieces.
7th These pieces are now in a dry state and ready to be carbonised in the
following manner.―
They are placed in some powdered coke, or advantageously in some powdered
wood-charcoal. The whole is then placed in an oven of fire-bricks in order to
prevent contact with the outside air. This oven is then heated till the inside of
the chamber is white-hot, and left thus for about forty-eight hours. It is then
allowed to cool after which the contents are removed.
8th The pieces are now hard and brittle, and if they are not sufficiently compressed,
they are then subjected to the following operation:-They are saturated with hydro
carbon oil or with tar in a metal cylinder and submitted to a pressure of about four
atmospheres, and to a temperature of 300 degrees or thereabouts.
9th The pieces thus saturated are again submitted to carbonization in a retort as
previously described.
10th For positive crayons the hollow is filled with plumbago before saturating
them and they are then carbonized again.
11th For cheap crayons of carbon graphite is mixed with an equal quantity of
carbon. The graphite is obtained from gas retorts. The compound is then mixed
with a little tar.
12th In place of making. the rods or crayons hollow previous to receiving the
plumbago, they can be filled with plumbago, by forcing out the body of the crayon
at the same time that the rod of plumbago is forcing its way in by piercing the
crayon, by means of two concentric pistons ready to fill or combine one of the parts
of the crayon either the hollow or solid.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed I declare that what
I claim is
1. The improved manufacture of electric crayons or carbons from the carbon
obtained from tar, either with the carbon alone or by means of a mixture of

page_text: graphite and carbon the graphite being obtained from gas retorts substantially as
herein before described.
2. The improved processes and operations described for the purpose of treating
the different ingredients used in the manufacture of electric crayons or carbons
substantially as herein before described.
3. The series of successive operations used in combination or separately sub-
stantially as described.
4. The improved manufacture of cheap carbons substantially as herein before
described.
5. The improved process of manufacturing positive carbons or crayons hollow
or solid at one operation substantially as herein before described.
1000
TONGUE & BIRKBECK,
Agents for the Patentee.