IMPROVEMENTS IN GALVANIC ELEMENTS
Year: 1882

page_text: LETTERS PATENT to John Henry Johnson of 47 Lincolns Inn Fields in the
County of Middlesex Gentleman for an Invention of "IMPROVEMENTS IN
GALVANIC ELEMENTS." Communicated to him from abroad by Aron Bernstein,
Doctor of Philosophy, of Berlin, Prussia in the Empire of Germany.
COMPLETE SPECIFICATION filed by the said John Henry Johnson at
the Office of the Commissioners of Patents on the 16th September 1882.
JOHN HENRY JOHNSON of 47 Lincoln's Inn Fields in the County of Middlesex
Gentleman "IMPROVEMENTS IN GALVANIC ELEMENTS." Communicated to me
from abroad by Aron Bernstein Doctor of Philosophy of Berlin, Prussia in the
Empire of Germany.
This Invention relates to galvanic elements the positive electrode whereof
consists of an amalgam of an alkali metal and its object is to render such elements
more efficient and to protect the said metal against the oxydizing influence of
the air.
It is known that by the employment of an amalgamated alkali metal for instance
potassium or sodium as electrode a galvanic element of considerable energy may
be produced. Nevertheless elements of this kind have hitherto not found any
practical use as on one hand the amalgam speedily oxydizes while on the other
hand certain arrangements introduced in order to obviate this inconvenience give
rise to an excessive internal resistance. Such elements may however be rendered
fit for practical purposes in the following manner.
The sodium or potassium amalgam to which a conducting wire of copper or
other suitable metal is attached is brought into a small bag or an envelope
consisting of any cloth which is not affected by the exciting fluid to be employed.
As such cloth may be used linen cotton or other sufficiently close fabrics inade
of vegetable fibres. The bag or envelope is drawn tightly together around the
conducting wire by a string and it is by preference at this point coated with
stearine paraffin rosin or other similar substance in order to prevent its upper
end from being soaked by liquid. Finally the envelope is impregnated with a
solution of caustic soda or potass containing in 100 parts from 30 to 50 parts by

page_text: weight of the alkali whereupon it is dried. Hereby the fabric becomes so close
that it will efficiently protect the amalgam against oxydation by the atmospheric
air (which is specially of importance while the element is not in use) whereas on
the other hand it presents but slight resistance to the galvanic current.
.
The plate of the amalgam thus prepared and enveloped and which forms the
positive electrode of the element is brought in close contact with the negative
electrodes and immersed with the same in the exciting liquid. In case copper is used
as negative electrode the liquid to be employed may consist as in Daniells' battery
in a concentrated solution of sulphate of copper to which crystals of the same salt
are added in order to keep up its full degree of concentration. If it be desired
to use a carbon plate the same is first moistened with diluted nitric acid and
thereupon plunged together with the enveloped plate of amalgam into a weak
solution of caustic soda. Various other materials may however be applied as
negative electrode and other solutions as exciting liquid provided that the latter
do not affect the envelope of the amalgam plate.
In respect to the form of the element the horizontal arrangement of the
electrodes has proved to be very advantageous. Supposing for instance a carbon
plate or a plate of copper having small feet be laid with the enveloped amalgam
plate on top thereof into a flat vessel of glass or gutta percha &c and the latter
then be so far filled with liquid that only the lower surface of the amalgam
becomes wetted an element is obtained which is but of small bulk in comparison
to its efficiency and besides the close contact between the electrodes and the
envelope or diaphragm which is required for the purpose of reducing as much as
possible the internal resistance of the element is thus attained in the simplest
manner. In order to facilitate the access of the liquid to the surfaces in contact
with each other it is advantageous to drill several holes into the copper plate.
The combination of two or more such elements to a battery does not require any
explanation as the same is carried out in the usual manner.
Having thus described the nature and object of this Invention and the manner
in which it is to be carried out in practice as communicated to me by my corre-
spondent I hereby claim as new and important features of the same :-
First. In a galvanic element a positive electrode consisting of the amalgam of an
alkali metal in combination with an envelope thereof serving as diaphragm and
made of a fabric not affected by the exciting liquid such as a fabric of vegetable
fibres and which is impregnated with a caustic alkalic solution substantially as
and for the purpose described.
Second. A galvanic element composed of a flat negative electrode and a positive
electrode consisting of a plate of analgamated alkali metal and enclosed in an
envelope having the nature and prepared as described both electrodes being placed
horizontally and so as to be both in contact with the said envelope substantially
as specified.
In witness whereof I the said John Henry Johnson have to this my
Specification set my hand and seal this sixteenth day of September One
1
J. HENRY JOHNSON (L.S.)