An Improved Diaphragm for Electrolytic Cells.
Year: 1893

page_text: Date of Application, 6th Feb., 1893
Complete Specification Left, 8th Apr., 1893—Accepted, 13th May, 1893
PROVISIONAL SPECIFICATION:
An Improved Diaphragm for Electrolytic Cells.
1 CHARLES NELSON WAITE of Newton Highlands, County of Middlesex, State
of Massachusetts, United States of America, Chemical Engineer do hereby
declare the nature of my invention to be as follows:-
My invention has for its object to provide an improved diaphragm for electrolytic
cells to be used in the electrolysis of alkaline haloids and it consists in a diaphragm.
composed of asbestos or other acid-resisting fibrous material containing in its pores
bi-chromatized gelatine.
The tenacity of bi-chromatized gelatine is not sufficient to enable it to be used
alone as a diaphragm and it cannot be used as a diaphragm when combined with
vegetable or other fibre destructible by acid because by the action of the chlorine,
bromine and the like, the chromium oxide is converted into chromic acid which
rapidly destroys the fibre. 1 have however found that if bi-chromatized gelatine
be strengthened by the use of a fibre which is resistant to acid like asbestos for
example a serviceable and very effective diaphragm can be produced. The
following is a method by which my invention may be carried out in practice. I
dissolve glue or isinglass in the smallest possible quantity of water and add to the
solution a quantity of bi-chromate of potash equal in amount preferably to 15 or
20 per cent. of the glue employed.
The bi-chromate of potash may be dissolved in a small quantity of water before
adding it to the solution of glue or isinglass. After the ingredients are thoroughly
mixed I add the asbestos or equivalent acid resisting and strengthening material
either by stirring the fibre into the mass and then forming the mixture into sheets
or layers or the solution may be brushed or painted onto ordinary asbestos paper or
millboard. After the sheet or layer has been formed in either of these ways it is
carefully dried and exposed to strong sunlight before using or the sheet or layer
may be passed through a bath of hypo-sulphite of soda or other reducing substance.
This renders the glue or isinglass insoluble and binds the strengthening fibre firmly
and produces a durable sheet or diaphragm which is of sufficient tenacity and which
is very efficient in preventing the diffusion of liquids in the cell while at the same
time it offers but slight resistance to the passage of the electric current.
Dated this 6th day of February 1893.
J. H. JOHNSON & Co.,
47, Lincoln's Inn Fields, London, W.C., Agents.
COMPLETE SPECIFICATION.
An Improved Diaphragm for Electrolytic Cells.
I CHARLES NELSON WAITE of Newton Highlands, County of Middlesex, State
of Massachusetts, United States of America Chemical 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:-
My invention has for its object to provide an improved diaphragm for electrolytic
cells to be used in the electrolysis of alkaline haloids and it consists in a diaphragm
composed of asbestos or other acid-resisting fibrous material containing in its pores
bi-chromatized gelatine.
The tenacity of bi-chromatized gelatine is not sufficient to enable it to be used
alone as a diaphragm and it cannot be used as a diaphragm when combined with
"

page_text: vegetable or other fibre destructible by acid because by the action of the chlorine,
bromine and the like, the chromium oxide is converted into chromic acid which
rapidly destroys the fibre.
I have however found that if bi-chromatized gelatine be strengthened by the use
of a fibre which is resistant to acid like asbestos for example a serviceable and very
effective diaphragm can be produced. The following is a method by which my
invention may be carried out in practice I dissolve glue or isinglass in the smallest
possible quantity of water and add to the solution a quantity of bi-chromate of
potash equal in amount preferably to 15 or 20 per cent. of the glue employed. The
bi-chromate of potash may be dissolved in a small quantity of water before adding
it to the solution of glue or isinglass.
After the ingredients are thoroughly mixed I add the asbestos or equivalent
acid resisting and strengthening material either by stirring the fibre into the mass
and then forming the mixture into sheets or layers or the solution may be brushed
or painted onto ordinary asbestos paper or millboard. After the sheet or layer has
been formed in either of these ways it is carefully dried and exposed to strong
sunlight before using, or the sheet or layer may be passed through a bath of hypo-
sulphite of soda or other reducing substance. This renders the glue or isinglass
insoluble and binds the strengthening fibre firmly and produces a durable sheet or
diaphragm which is of sufficient tenacity and which is very efficient in preventing
the diffusion of liquids in the cell while at the same time it offers but slight
resistance to the passage of the electric current.
Having now particularly described and ascertained the nature of my said
invention and the manner in which the same is to be performed I declare that what
I claim is :-
:-
A diaphragm for electrolytic cells the said diaphragm consisting of asbestos or
other acid resisting fibrous material and bi-chromatized gelatine substantially as
hereinbefore described.
Dated this 8th dow of Amil 1000
J. H. JOHNSON & Co.,
Agents.