214 PROFESSOR A. CRUM BROWN AND DR JAMES WALKER ON THE 



fore the greater will be the probability that they react among themselves and not on the 

 water used as solvent. A special experiment served to confirm this conclusion. With 

 the apparatus arranged as above, a solution containing 15 grams of ethyl potassium 

 malonate yielded on electrolysis 4*5 grams of succinic ether. A perfectly similar solution 

 under precisely the same conditions, with the exception that the current was reversed, 

 gave scarcely '5 gram of the ether, and that not nearly so pure as in the first case. 

 Still using the same solution, we again reversed the current, and obtained 4 more grams 

 of the diethyl succinate. This proves beyond doubt that with a large anode — the crucible 

 — the discharged anions, being spread over a wide area, have not the opportunity of 

 reacting with each other, and are consequently forced to attack the water. The original 

 acid is thereby regenerated, and this is speedily neutralised by the potash produced at 

 the cathode, so that everything returns to its primary state, the chief result being the 

 decomposition of water. 



RCOOK = RCOO + K 



RCOO + HOH = R-COOH + OH 



K+HOH = KOH+H 

 RCOOH + KOH = R-COOK + H 2 



The above experiment seems to stand in direct contradiction to an observation made by 

 Jahn,* who found that on the electrolysis of sodium acetate, more ethan was formed when 

 his anode was large than when it was small. The difference between his electrodes was, 

 however, not nearly so great as that between ours, the areas of which were in the ratio 

 300 : 1, and consequently the difference between the quantities of ethan he obtained was 

 also small, so that perhaps other circumstances might have occasioned the discrepancy. 



We derived our electricity from a battery of twenty-four secondary cells connected so 

 as to give an electromotive force of twelve volts. In the course of the investigation it 

 appeared that a high temperature lessened to some extent the yield of the synthetic pro- 

 duct, which obliged us to keep the current intensity below a maximum of five amperes. 

 With this current, the heat developed by the passage of the electricity through the 

 solution can be conducted away by a stream of cold water flowing round the platinum 

 crucible. A probable cause of the diminution of the quantity of ester formed at a high 

 temperature is the readiness with which the potash formed at the cathode saponifies the 

 ethyl-potassium salt in hot aqueous solution. This saponification, however, is always in 

 great measure prevented by the gases evolved at the electrodes serving to keep the 

 solution constantly stirred up, so that the potash is at least partially neutralised by the 

 carbonic acid liberated at the anode. A special current of carbonic acid passed through 

 the solution seems to have no beneficial effect. 



One point to be attended to is that the solution should not be too concentrated. The 

 best strength is from 1 '5 to 2 parts of ethyl-potassium salt to 1 part of water. It is 

 a circumstance of the greatest moment for the success of this electrolytic synthesis of the 

 dibasic acids that the ethyl-potassium salts are so extraordinarily soluble in water. Even 



* Jahn, loc. cit., 423. 



