Sept., 1921
T H E J O G R N A L OF INDUSTRIAL A N D ENGINEERING CHEMISTRY
769
I. R. drop through the solution results in somewhat higher energy consumption. 6-It is belieTed that the effect of practically all variables (such as temperature, current density, anolyte composition, etc.) on the current efficiency is in reality due to tlie variations which these factors cause in the oxygen overvoltage, a high oxygen overvoltage being necessary f o r high current efficiencies in permanganate production. It is hoped to present further evidence bearing upon this point in a later paper. 7-The essential conclusions as t o the optimum operating conditions and the efficiencies obtainable have all been confirmed by continuous operation of a full-sized commercial TEUPDRATCRE cell, using five ferromanganese bars, each 5 in. X 1.5 in. X 35 in., as the anode. 28” C. or lower
current efficiency was only about 2 per cent less than with carbonate. The clue which led to the discovery of the conditions f o r eliminating the coating was furnished by a 5-hr. electrolysis with a potassium carbonate solution of higher concentration than had been used previously (namely, 30 per cent K,CO,), a t the end of which it was found that the anode surface, after the adhering permanganate solution had been rinsed off, was brightly metallic and free from the usual coating. Further experiments showed that under the following conditions of temperature and initial anolyte, electrolysis proceeds smoothly and continuously for an indefioite length of time without coating formation : RODUCT
KhfnOa NaMnOc
AKOLYTE
,KGOa solution E% KzCOs solution
Saturated (77,) NazC03 solution
12” C . or lower 10” C. or lower
Short periods of operation at 1 0 ” higher than the above temperatures were harmless in the case of potassium. I f it is desired to build up a concentration of sodium permanganate above about 3 per cent, however, it is necessary to add solid Na,CO, to the anolyte from time to time. While not many of these long, continuous runs ( 7 to 1 0 days in duration) were made, nevertheless sufficient data were obtained to indicate that the current efficiency and energy consumption under such conditions are about the same a s in the runs on which the curves presented in this paper are based, and the anodes are clean and bright a t the end of the operation.
Bakelite Company Wins Decree
The General Bakelite Company of New York was awarded a decree in its suit against the General Insulate Company of Brooklyn charging infringement of three Bakelite patents. The decision against the defendant was handed down by Judge I. Chatfield of the United States District Court, Eastern District of New York, on August 2 , 1921. The three Bakelite patents involved were No. 942,699, 492,852 and 939,966 commonly designated a s the Heat and Pressure Patent, the Fibrous Materials or Indurated Product Patent and the Comminuted Mixture or Molding Patent, all of which have been sustained and declared insUM&IARY fringed by the Court. The decision is remarkable for the comprehensiveness 1-The foregoing article presents in tabular and graphic form the results of extensive experimental work on the and the clearness with which Judge Chatfield has handled more important factors involved in the electrolytic produc- a highly technical subject, involving fine distinctions betion of sodium and potassium permanganates from ferro- tween chemical and physical processes and between actual inention and the manufacture of a known substance manganese anodes. 2-In the investigation of the effect of anode composition by variations in technique of production. Particular init was found that the higher the manganese content of the terest is attached to this decision b‘ecause t h e defendant a molding Insulate Company-is electrode, the higher the current efficiency, anodes contain- in t h e case-General concern doing business in Brooklyn, New York, and using ing less than 40 per cent giving practically no yield under the products manufactured by the Redmanol Chemical any conditions. Other constituents at the anode seem to hive comparatively little effect except in the case of cobalt, Products Company of Chicago and a s Judge Chatfield said in his opinion: about 2 per cent of which practically destroys tlie perman“The record shows t h a t in fact the Redmanol Company ganate producing power of a ferromanganese electrode. I n view, however, of the greater cost and brittleness of anodes has stood behind the defendant in the trial of this action, containing more than 80 per cent manganese, the commer- and in so f a r as investigation of t h e prior art and discussions of questions of patentability a r e concerned, the cial 80 per cent ferronianganese appears to be the best anode material f o r technical operation, and most of the Redmanol Company h a s a s freely and fully presented its evidence a s if the action had been against the Redmanol experiments were made with such anodes. 3-Possible anotytes are alkali metal salts of weak acids, Company for infringement of the plaintiff’s patents in and alkali metal hydroxides. The best anolyte appears t o the manufacture of the synthetic gum itself.” The Redmanol Company had no office in New .Yorkbe a solution of alkali metal carbonate, the carbonate being destroyed in the course of electrolysis and replaced by per- hence the indirect action of the General Bakelite Commanganate uncontaminated by manganate or other salts. pany in filling a Bill of Complaint against one of the Hydroxide solutions are interesting from the theoretical users of the Redmanol products. The Bill of Complaint viewpoint, in that they give a sharp minimum in current was filed September 18, 1917, but a trial could not be obtained until March 31, 1919. The trial lasted many efficiency at an intermediate O H concentration. &The operating temperature should be as low as pos- weeks in open court, the final arguments taking place sible (10” to 20°C.). Low temperature gives highest effi- , on June 22, 1919. The decision itself covers 36 printed pages, and reviews ciency and lowest energy consumption, and makes possible the continuous operation of the anode (provided the initial t h e various patents t h a t have been issued both in the carbonate concentration is high). High temperature gives United States and foreign countries f o r the preparation lower current efficiency and promotes a “ s k i n effect” on of materials generally classified as synthetic resins. The the anode surface which gives rise to excessive voltages. fact that the Baekeland patents go further than any pre6-A current density of about 6 amp. per sq. dm. gives vious patents in covering the preparation of materials the minimum energy consumption. The optimum operating that are of practical value and prepared according t o current density is somewhat higher than this. At lower exact processes yielding definite products, is deflnitely aurrent densities the current efflciency falle off rapidly ; shown. The decision is a valuable contribution to at highar current densities it rises mlawly, but the increased chemical patent literature,
