An Improved Method, Means, or Process of Producing Caustic Soda and Chlorine Gas by the Electrolysis of Common Salt in Solution.
Year: 1894

page_text: Date of Application, 23rd Apr., 1894-Accepted, 25th May, 1894
COMPLETE SPECIFICATION.
An Improved Method, Means, or Process of Producing Caustic
Soda and Chlorine Gas by the Electrolysis of Common Salt
in Solution.
I, THOMAS DRAKE, of New Street, Huddersfield, in the County of York,
Solicitor, 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 consists in a new method or means of producing caustic soda and
chlorine gas by the action of electricity on common salt in solution.
In carrying out my invention I use an electric cell containing two chambers, the
outer one being partially filled with mercury, the use of which mercury forms an
important feature in my invention for manufacturing caustic soda.
In order that the nature and object of my improvements may be more fully
understood and put into practical operation I will now make reference to the
annexed sheet of drawings which illustrates an arrangement of vessels and an
electric cell the latter resting upon a pedestal A. The cell is composed of an outer
vessel B made of cast iron, the inner walls or sides of which are carburised. A
porous pot C is placed within the carburised cast iron vessel, leaving a space
between the inner walls of the outer vessel B and the porous pot C. This porous
pot contains two or more carbons cast to a disc of lead D which forms the lid
of the said porous pot, which lid is the anode of the cell. E is the cathode and it
is connected to the cast iron vessel B. The space F formed between the outer
vessel B and the inner vessel C is filled with mercury to the height of the pipe G
the end of which is stopped by a plug. After the introduction of mercury into the
space F the tap H of vessel I (which is filled with a strong solution of common
salt) is opened, allowing the liquor therein to flow into the anode side of the cell
until it rises to the overflow J when it falls into the depositing tank or vessel K.
In the process of manufacture, the supernatant liquor in vessel K flows over
through pipe L into vessel M which when full is forced or pumped back into the
upper vessel and thus the circulation of the liquor is continued. The vessel N
is charged with water and flows through pipe O into the space F resting upon the
surface of the mercury until the water rises to the level of the overflow pipe P
when it passes into the vessel Q which when full is forced or pumped back into the
vessel N and so the circulation of the liquor continues. The electric current
produced by a dynamo being now connected to the two poles of the cell, the
electrolysis commences and the brine in the inner cell C decomposes and chlorine
gas passes off by pipe R, whilst sodium combines with the mercury in the annular
space F.
This combination of sodium and mercury is lighter than mercury. The action
of the flow of water through pipe O is to oxidise the sodium to soda with liberation
of hydrogen, the said water being discharged through pipe P.
This process may be continued until the solution of caustic soda attains any
desired gravity or strength.
I would here observe that the mercury employed herein sustains no waste by the
action or process herein described, but remains within the space F until such times
as the inner vessel or porous pots or carbons have to be replaced when the mercury
may be drawn off by pipe S.
I would also observe that the chamber of the porous pot above the overflow
pipe J should be charged inside and outside with paraffin or other like body to
destroy its norosite

page_text: Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed and carried out, I
declare that, what I claim is :-
Firstly. The manufacture of caustic soda by the use of mercury and the action
of electricity in manner berein described and shewn in the drawings.
Secondly. The manufacture of caustic soda by the use of mercury and the
circulation of water thereon and the action of an electric current in the manner
herein described and shewn in the drawings.
Dated this 21st day of April 1894.
TASKER & CROSSLEY,
Huddersfield, Agents.