The decomposition of a solution of common salt, and its conversion into chlorine gas and caustic soda solution by means of an electric current, has long been a study with electro-chemists.  Experimentally it has often been effected, but so far as we are aware, the success of this method of production has never until now been demonstrated on a sound commercial basis.  The solution of this important industrial problem is due to Mr. James Greenwood, who has been engaged in the development of electro-chemical processes for many years.  The outcome of this is that Mr. Greenwood has now perfected an electrolytic process for the direct production of caustic soda and chlorine, as well as other chemical products, the operation of which we recently inspected at Phoenix Wharf, Battersea, London.  One of the special features in connection with Mr. Greenwood’s new departure is the novel and ingenious method by which the electrolyzed products are separated, and their recombination rendered impossible.  This object is attained by the use of a specially constructed diaphragm which is composed of a series of V-shaped glass troughs, fitted in a frame within each other with a small space between them, which is lightly packed with asbestos fiber.  Another important feature of the apparatus is a compound anode which consists of carbon plates, with a metal core to increase the conductivity.  The anode is treated in a special manner so as to render it non-porous and impervious to attack by the nascent chlorine evolved on its surface.  No anode appears ever to have been invented that is at all suitable for working on a large scale, and the successful introduction of this compound anode, therefore, constitutes a marked advance in the apparatus used in electrolytic methods of production.

The apparatus by which the new process is being successfully demonstrated on a working scale has been put up by the Caustic Soda and Chlorine Syndicate, London, and has been in operation for several months past.  The installation consists of five large electrolytic vessels, each of which is fitted up with five anodes and six cathodes arranged alternately.  The anodes and cathodes are separated by the special diaphragms, and each vessel is thus divided into ten anode or chlorine sections and ten cathode or caustic soda sections.  The anodes and cathodes in each vessel are connected up in parallel similar to an ordinary storage battery, but the five electrolytic vessels are connected up in series.  The current is produced by an Elwell-Parker dynamo, and the electromotive force required to overcome the resistance of each vessel is about 4.4 volts, with a current density of 10 amperes per square foot of electrode surface.  The anode sections, numbering fifty altogether, are connected by means of tubes, the inlet being at the bottom and the outlet at the top of each section.  The whole of the cathode sections are connected in the same manner.  In commencing operations, the electrolytic vessels are