An Improved Apparatus for Economically Effecting the Double Decomposition of Certain Substances by the Aid of Electricity.
Year: 1889

page_text: Date of Application, 9th Feb., 1689
Complete Specification Left, 9th Dec., 1889-Accepted, 11th Jan., 1890
PROVISIONAL SPECIFICATION.
An Improved Apparatus for Economically Effecting the Double
Decomposition of Certain Substances by the Aid of Electricity.
We, WILLIAM HENRY DOWLAND of 54 Glengall Road London S.E. engineer, and
WALTER MILLS of 232 Friern Road London S.E. analyst do hereby declare the
nature of this invention to be as follows:-
haloids,"
There are a variety of substances, technically known in Chemistry as
which are capable of undergoing double docomposition. This decomposition is usually
effected by the aid of chemicals and .heat; we however accomplish the same result
more economically in the following way.
We construct a vessel of earthenware or other suitable substance, with or without
flanges, of convenient dimensions with moveable tops. In the centre of the vessel is a
partition, moveable or fixed, made of any suitable material such as wooi, china,
earthenware, glass, asbestos, or of these materials in combination; this partition is
perforated if necessary with holes for a distance not exceeding one third of its height
from the bottom of the vessel when placed in position therein, and on the summit of
this partition and on either side thereof are flanges to carry the moveable tops. These
tops are constructed of glass, wood, earthenware, or other suitable material, either
semi-circular or flat in shape, with or without flanges, closed at each end, with orifices
suitable for attaching pipes or tubes, and with or without legs. The main body of the
vessel may be steam jacketed, placed in a water-bath, or otherwise arranged so that
heat may be communicated, if necessary, to its contents.
The way in which we use the apparatus is as follows: the substance to be
decomposed is placed in the vessel, in a state of solution if necessary; the tops are
secured in position if the partition is used, and if not then the tops with legs are
inserted into the vessel. Suitable electrodes are introduced, an electric current is
passed, through the contents of the vessel, to which at the saine time heat may be
applied if necessary. Under these conditions the contents of the vessel are split up,
any volatile products rising into the moveable tops and passing through the orifices
into pipes or tubes and thence into receptacles. Proper means are adopted for
drawing off the decomposed contents of the vessel and re-supplying it. By means of
this apparatus we collect and utilise all the products of decomposition, some of which
are lost by the methods at present in use.
Dated this 9th day of February 1889.
WILLIAM HENRY DOWLAND.
WALTER MILLS.
COMPLETE SPECIFICATION.
An Improved Apparatus for Economically Effecting the Double
Decomposition of Certain Substances by the Aid of Electricity.
We, WILLIAM HENRY DOWLAND of 54 Glongall Road, London S.E. engineer, and
WALTER MILLS of 232 Friern Road, London S.E. analyst 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 :-
Our invention has for its object the utilisation of the products of the electro decom-
position of a large class of substances known as haloids, whereof common salt is the
most important commercially. In order to do this we isolate and collect as fast as
they are produced the various products of such decomposition. The apparatus and
method of doing this we now proceed to describe, taking for our illustration the
apparatus and method by which we decompose common salt, which apparatus and

page_text: method with trifling and non-essential variations and modifications may be used for
other luloids.
The shape of the main vessel which we first construct is immaterial, but we prefer
to make it rectangular; a convenient size is 2 feet long 1 foot wide, 7 inches deep,
but these dimensiors may be varied; when it is necessary to heat its contents, which
may sometimes be found desirable, flanges are formed on the outside of the vessel, so
as to facilitate the application of a steam jacket, or of some non conducting material
to the siles. In or about the centre of this vessel and extending across it we place a
partition which must be made of some material either in itself capable of permitting
the passage of an electric current, such as porous earthenware, or perforated with
holes if a non porous material. In this latter case the holes must not extend to a
greater height from the bottom of the vessel than about one third of the vessel's
depth. We find in practice that it is preferable to employ a porous earthenware plate
for this partition although a framework of wood covered with asbestos cloth or
parchment will answer the same purpose. A flange or projection about 1 inch wido
runs along each side of this partition at a distance of 1 inch or thereabouts from the
summit thereof, or, when the material of the porous plate is sufficiently thick, a groove
is formed in the summit of it about half an inch deep and of a similar width. The
object of the flanges or the groove is to facilitate the application of the tops or
coverings, and making the same gas-tight by luting or washers.
In the stead of
similar
the tops with legs which we mentioned in our provisional specification wo prefer to
subdivide one of the two compartments thus forined in the main vessel with
division. We thus form three compartments in the main vessel.
To the two outside compartments we affix noveable tops; the shape of these
tops is immaterial, the important essential being that they should be capable of
attachment to the apparatus, so as to make gas-tight joints with the apparatus all
round; these tops are made of any material which will not conduct electricity, such
as glass wood, earthenware, or vulcanite. Orifices to which pipes may be readily
attached are formed in these moveable tops. In any convenient and well-known
manner electrodes of some suitable material, preferably carbon, are introduced into
the two outer compartments these electrodes are connected with any source of
electricity, such as a battery or dynamo, positive electrodes being inserted in the
smaller outer compartment, and the negative electrodes occupying the larger outer
compartment. We now describe the method of using this apparatus, presuming
that the haloid which it is wished to decompose is common salt. We place in the
central and smaller compartments a saturated solution of common salt; into the
larger compartment we pour water. We then place in the central compartiment a
quantity of free salt, and in the largest compartment containing the negative
electrodes a small quantity of caustic soda. We next place one of the moveable tops
over the smaller outer compartment and secure it in position making a gus-tight
joint. We then connect the electrodes in both outer compartments with the source
of the electric current in the usual manner; as the current flows through the
solutions in the apparatus, the solution of salt therein is split up. Chlorine is given
off at the positivo and hydrogen at the negative electrodes. The free salt in the
central compartment replenishes the fluid in the compartanent containing the positive
electrodes with salt, the other outer compartment being similarly replenished with
caustic soda. Any of the well known methods for preventing polarization at the
negative electrodes are employed, and thus a continuous stream of hlorine is evolved
at the positive electrode while the solution surrounding the negative electrode becomes
more and more rich in caustic soda until its density is sufficient to warrant drawing
off the fluid and then a fresh weak solution is supplied as at the commencement of
the operation. Salt is fed into the central compartment from time to time as
necessary.
The foregoing operation may also be performed on a small scale by inserting a
porous pot containing an electrode or electrodes in a larger porous pot & placing the
pots so arranged in a larger vessel also containing electrodes. The annulus or space
between the two porous pots in this case takes the place of the contral compartment

page_text: herein before described and is used in the same way, while the outer vessel takes the
place of the largest of the aforesaid compartments and the central porous pot the
place of the smaller said compartment. If the top of the central porous pot is closed
the gas evolved may be readily collected. In cases where it is necessary to employ
more than one apparatus at the same time we use an electric current of sufficient
intensity to enable us to couple up the apparatus in series.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed we declare that what we
claim is :
1. The method of and apparatus for decomposing haloids by electricity and
collecting the products of decomposition substantially as hereinbefore described.
2. The apparatus with two porous divisions between which the free haloid under-
going electrolysis is contained.
3. The use of two separate liquids in the manner and for the purposes hereinbefore
described.
Dated this 9th dow of December 1880
WILLIAM HY. DOWLAND.
WALTER MILLS.