An Improved Carbon Stick or Pencil for Arc Lights.
Year: 1891

page_text: COMPLETE SPECIFICATION.
An Improved Carbon Stick or Pencil for Arc Lights.
1, HERBERT JOHN ALLISON, of 52, Chancery Lane, London, in the County of
Middlesex, Patent Agent, do hereby declare the nature of this invention (which
has been communicated to me from abroad by Barton Brewer Ward, of the City,
County, and State of New York, United States of America, Electrician), and in
what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement :-
My invention relates to carbon sticks or pencils for use in that class of arc
lights in which two sticks or pencils are presented end to end and the arc plays in
the space between the same.
The object of my invention is to produce a carbon which will be free from
hissing and sputtering even though the arc is short, and which may be operated
with a low voltage of current and yet maintain an arc which shall not go out
readily.
My invention consists of a carbon stick or pencil having a longitudinal bore or
passage at or near the centre the wall of which is covered with a thin film or layer
of a silicate, preferably a silicate of soda or a silicate of potash. With silicate of
soda I have obtained excellent results, and I generally use this substance on account
of its cheapness.
In the accompanying drawings:
Fig. 1, is a longitudinal section through a carbon stick or pencil embodying my
invention, and shows the manner in which the same is presented to the opposite or
negative carbon while being consumed.
Fig. 2, is a cross section through the carbon stick or pencil.
As shown in Fig. 1, the carbon stick or pencil has a longitudinal bore or passage
at or about its centre to the walls of which are applied a thin layer or film B,
of the material which shall vaporize in the arc and shall produce a vapour of
considerable conducting capacity so as to prevent the breakage of the arc
running on low voltage. In the drawing the thickness of the layer is shown greatly
exaggerated.
As before stated, I prefer to employ silicate of soda as the material of this film
or layer. In order to apply it I use the ordinary solution of a silicate, and after
placing a few drops at one end of the bore or passage, distribute the same over the
interior surface by means of a blast of air applied by means of a nozzle or other
device and forced through the bore or passage. By this means the silicate is
distributed evenly over the interior surfaces and after being allowed to dry, the
carbon is ready for use.
The carbon stick or pencil constructed with a bore or passage and provided with
a film or layer of the material described not only possesses the advantages
hereinbefore described over previous constructions but may be also cheaply and
readily manufactured.
Having thus particularly described and ascertained the nature of my said inven-
tion and the manner in which the same is to be performed, I declare that what I
claim is :-
1. As a new article of manufacture, a carbon stick or pencil having a longi-
tudinal bore or passage, the walls of which are coated with a thin film or layer of a

page_text: 2. As a new article of manufacture, a carbon stick or pencil having a longi-
tudinal bore or passage at or near its centre, the walls of which are coated with
a thin layer or film of a silicate of soda, as and for the purpose described.
101
ALLISON BROS.,
Agents for the Applicant.