Year: 1888

page_text: I, CARL ANTON JOHANNES HUGO SCHROEDER of 17, Althorpe Road, Upper Tooting in
the County of Surrey, Electrical Engineer 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:—
Carbons to be prepared by my mode may have any kind of structure from the
densest to the loosest, and may be of any degree of hardness. The preparation is
adapted to the properties of the carbons as follows:
I. Dense carbon is first dipped into a dilute solution of calcic-chloride so that the
carbon is moderately saturated, after which it is taken out of the solution and left to
dry; after it is dry, it is ready for use.
II. Carbon of loose structure is likewise first dipped into a dilute solution of
calcic-chloride and remains therein until the carbon is moderately saturated, after
which it is taken out of the solution; the carbon is than brought, whether dry or not,
into a bath of a solution of potassic-chlorate or potassic-nitrate or sodic-nitrate of
any other potassium or sodium compound which is soluble in water, or any composition
of such salt solutions, in which solution the carbon must remain for a time, according
to its density, hardness and other properties. It is preferable to apply this solution
concentrated as well as hot or at a boiling temperature. After the carbon is taken out
of this bath, the carbon is exposed to heated air in such a manner that the carbon first
dries and then gets considerably hot.
The carbon is now brought in this hot condition into a bath of fused potassic-nitrate
or sodic-nitrate or potassic-chlorate or any other potassium or sodium compound which
is soluble in water.
The bath of these fused salts or their composition is situated in a vessel made of
suitable material, such as Iron, Porcelain, Platinum etc.
The carbon must remain in the bath until the carbon is either completely or partly
penetrated by the salts, the amount of penetration depending on the electro-motive-
force of the current for which the carbon is to be used.
It is good to give the carbon in the vessel a swinging motion during this manipula-
tion so as to let the preparation act as uniformly on the carbon as possible.

page_text: When the carbon is taken out of this bath, it is, while still hot, wiped with a piece
of asbestos or any other suitable appliance in order to remove the excess of the salts
adhering to the carbon. The carbon is now ready for use, but it is preferable to
remove the outer layer by mechanical or other suitable means on that part of the
carbon where the current has to pass.
The carbons prepared by me furnish a useful electric-light under less favourable
conditions of strength and tension of electric-current than any carbons hitherto
employed.
Thus, my prepared carbons will burn, giving a good and practicable arc-light with
a current of 20 volts electromotive force, and a strength of 7 ampères.
MODE OF APPLYING THE CARBONS IN THE WAY PREPARED AS DESCRIBED.
Carbons prepared in these two different ways may be used or burnt in various ways;
the following is the most to be recommended:
The carbon of the preparation No. I, namely the carbon of dense structure, is
preferably employed of a smaller diameter than the carbon of the preparation No. II
and is taken as the negativ pole, generally situated below; while the carbon of the
preparation No. II namely the looser carbon of larger diameter, that may consist of
one or more pieces, is to be applied to the positive pole generally situated at the top.
Having now particularly described the nature of my said invention, and in what
manner the same is to be carried out, I declare that what I claim is:
The preparation of the carbons herein particularly and substantially described.
Dated this 26th day of Anril 1888
of April 1888
CARL ANTON JOHANNES HUGO SCHROEDER.