Improvements in the Manufacture of Porous Diaphragms for Electrolytic Apparatus.
Year: 1899

page_text: Date of Application, 9th Mar., 1899
Complete Specification Left, 22nd Aug., 1899-Accepted, 23rd Sept., 1899
Improvements in the Manufacture of Porous Diaphragms for
Electrolytic Apparatus.
We, TREVENEN JAMES HOLLAND, of Mount Ephraim House, Tunbridge Wells,
Colonel, C.B., Retired List, H.M. Army, and ARTHUR PILLANS LAURIE, M.A.,
D.Sc., of Monkwood Cottage, Laughton, Essex, Consulting Chemist, do hereby
declare the nature of this invention to be as follows:-
The present invention has for its object to produce porous diaphragms, for
electrolytic purposes, from cement, which is in itself practically non-porous, in a
more convenient and satisfactory manner than hitherto.
Porous cement diaphragms have been hitherto made either by mixing the
cement with powdered porous material, which remains in the cement when set,
and gives a certain degree of porosity to the diaphragm, or by mixing the
cement with soluble salts, or other materials which can be dissolved out of the
cement, when set, so as to leave it porous.
It is probable that the latter method would give the greater porosity, if the
solvent could be relied upon to reach and dissolve all the added materials which
are required to be removed. There are, however, considerable difficulties in the
way of obtaining a diaphragm by means of dissolution, which difficulties it is the
object of the present invention to avoid, by employing an added material capable
of removal in a different way.
Accordingly, we propose to mix with the cement a volatile material which is
insoluble in water, but which may be removed by converting it into vapour after
the cement has been set. Such a material is naphthaline or anthracene about
20% of which may be added, in a crystalline powdered state, to the dry cement,
and afterwards volatilized by means of heat. This material is not affected by the
water used in mixing, but may be easily removed after the cement is set, by
means of volatilization, so as to leave the cement with a considerable degree of
porosity. The heat may be conveniently applied by boiling the diaphragms in
water for a short time.
In this way, the removal of the added material is ensured, and that in a very,
simple and expeditious manner.
Improvements in the Manufacture of Porous Diaphragms for
Electrolytic Apparatus.
We, TREVENEN JAMES HOLLAND, of Mount Ephraim House, Tunbridge Wells,
Colonel, C.B., Itetired List, H.M. Army, and ARTHUR PILLANS LAURIE, M.A.,
[Price Sd1

page_text: D.Sc., of Monkwood Cottage, Laughton, Essex, Consulting Chemist, do hereby
declare the nature of this invention and in what manner the same is to be per-
formed to be particularly described and ascertained in and by the following
statement:.
1
The present invention has for its object to produce porous diaphragms, for
electrolytic purposes, from cement, which is in itself practically non-porous, in a
more convenient and satisfactory manner than hitherto..
Porous cement diaphragms have been hitherto made either by mixing the
cement with powdered porous material, which remains in the cement when set,
and gives a certain degree of porosity to the diaphragm, or by mixing the
cement with soluble salts or other materials which can be dissolved out of the
cement, when set, so as to leave it porous.
Diaphragms with a certain degree of porosity can be constructed by both of these
methods, but it is found that better results can be obtained in the following
manner:
According to this invention, we propose to mix with the cement a volatile
material which is insoluble in water, but which may be removed by converting it
into vapour after the cement has been set. Such a material is naphthaline or anthra-
cene, about 20% of which may be added in a crystalline powdered state to the dry
cement, and afterwards volatilized by means of heat." This material is not
affected by the water used in mixing, but may be easily removed after the
cément is set by means of volatilization, so as to leave the cement with a con-
siderable degree of porosity.
The moulding of the cement into slabs or diaphragms is effected in the usual
way, and the volatilization of the added material is accomplished by means of
heat applied in any convenient manner.
Having now particularly described and ascertained the nature of our said.
invention and in what manner the same is to be performed, we declare that what
we claim is:
The herein before described method of manufacturing porous diaphragms from
cement, comprising the addition of material insoluble in water to the cement,
and the subsequent removal of the same by volatilization, substantially as set
forth.