Improvements in Platinized Electrodes.
Year: 1893

page_text: Date of Application, 13th Jan., 1893
Complete Specification Left, 25th Oct., 1893-Accepted, 25th Nov., 1893
PROVISIONAL SPECIFICATION.
Improvements in Platinized Electrodes.
I HARRY THEODORE BARNETT M.I.E.E. of 14 Narcissus Road London, N.W.
do hereby declare the nature of this invention to be as follows:-
There are many purposes for which an electrode whose active surface is platinum
is required. Owing to the high cost price of this metal it has been usual where
possible to utilize some other conducting substance as a base upon which the
platinum may be deposited as a thin film so that its function may be obtained at
a minimum cost, the spongy deposit being usually preferred to the reguline because
of its greater activity.
As ordinarily constructed these electrodes do not offer any great surface & rapidly
deteriorate when used as the negative electrode in a non-depolarizing primary
battery.
To greatly increase the active surface which among other advantages will
facilitate combination, reduce electrical resistance, minimise or abolish the
disruptive effect of the liberation of gas, & at the same time protect the platinum
deposit from mechanical injury I prefer to construct the conducting support upon
which it is deposited with a number of interstices or projections.
Where carbon is used as the conducting support I prefer to reduce the platinum
by the same heating which effects the carbonisation of the said support or any
part thereof as this not only effects a saving in fuel but ensures a more intimate
adhesion between the particles of platinum & carbon.
The form which I prefer for the said conducting support is that of a textile,
lamellar, or solid body whose surface is covered with a number of outstanding
filamentary projections.
Dated this Twelfth day of January 1893.
HARRY THEODORE BARNETT.
COMPLETE SPECIFICATION.
Improvements in Platinized Electrodes.
I, HARRY THEODORE BARNETT Mem. Inst. Elec. Engrs. 14 Narcissus Road
W. Hampstead, London N.W. 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 :-
There are many purposes for which an electrode whose active surface is platinum
is required. Owing to the high cost price of this metal it has been usual where
possible to utilize some other conducting substance as a base upon which the
platinum may be deposited as a thin film, so that its function may be obtained at a
minimum cost, the spongy deposit being usually preferred to the reguline because
of its greater activity.
As ordinarily constructed these electrodes do not offer any great surface and
rapidly deteriorate when used as the negative element in a non-depolarizing primary
battery, frequent replatinizing being necessary.
Silver is the most commonly used conducting support, silvered copper and lead
have also been used, but with unsatisfactory results. Carbon is rarely used, owing
to the difficulty hitherto experienced in making a good and incorrodible connection.
To greatly increase the active surface and so facilitate combination, reduce the
electrical resistance, and minimise or. abolish the disruptive effect of any gases
which may be liberated and at the same time protect the platinum deposit from
Price 81

page_text: mechanical injury I prefer to construct the conducting support (upon which it is
deposited) with a number of interstices or projections.
A silver conducting support inexpensive in proportion to its surface is very fine
silver wire woven into gauze form. A better but more expensive silver support
consists of strips of silver foil or gauze arranged close together with their surfaces
parallel and their edges to the liquid.
Where carbon is used as the conducting support I prefer to reduce the platinum
by the same heating which effects the carbonization of the said support or any part
thereof. This is good for several reasons but chiefly because of the very close
union it engenders between the atoms of platinum and the base upon and into
which they are deposited. An electrode of this class may be produced by dipping
carbon putty, wood, celluloid, cotton or other suitable substance in a solution of
chloride of platinum and afterwards carbonizing the same. The platinum might be
reduced upon the said substances previous to their complete carbonization as partial
carbonization would be caused by a heat sufficient to reduce the platinum.
The form which I prefer for the said conducting support is that of a solid, textile,
or lamellar body whose surface is covered with a number of outstanding filamentary
projections.
Silver, carbon, or any other suitable material may be used to construct them of.
A convenient method of manufacture, in which the conducting support is a
compound solid cylindrical and textile mass, is as follows:-Electric light carbon
rods are pasted and dried and tightly bound with freshly pasted strips of cotton
velvet that has been previously pasted and dried, they are dried slowly in an air
current and are then sprayed on the pile with chloride of platinum solution, after
which they are quickly dried in an oven and then carbonized while packed in
charcoal dust in a gas or other muffle furnace.
Any of these electrodes may be used in primary or secondary electric batteries
or for electrolysis and for any other purpose where an extended surface and the
properties of platinum as a liberant or absorbent are of value.
Having now particularly ascertained and described the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
Claim I. In a platinized electrode, a conducting support for the deposited
platinum constructed with a number of interstices or projections substantially as
and for the purpose described.
Claim II. In a platinized carbon electrode, the reduction of the platinum upon
the conducting support by the same heating which effects the carbonization of the
said support or any part thereof substantially as described.
Claim III. In a platinized electrode, a conducting support for the deposited
platinum consisting of a body whose surface is covered with a number of outstanding
filamentary projections substantially as described.
Dated this 20th day of October 1893.
H. T. BARNETT.