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



as in their case it would be necessary to use a divided cell. The potassium salts of the 

 amic acids, again, would yield an insoluble amide. By far the best substances to use, then, 

 are the ester salts, which are distinguished by their great solubility in water, are easily 

 obtainable in sufficient purity for electrolysis, and give as product an oil at once removed 

 from the sphere of action. 



In the following pages we describe the experiments made in the individual cases, and 

 the products thereby obtained. 



Synthesis of Succinic Acid. 



Ethyl potassium malonate is easily prepared according to the directions of Freund* 

 from diethyl malonate and the calculated quantity of alcoholic potash. The salt thus 

 obtained was electrolysed in the manner already mentioned, the product being a colour- 

 less oil, which, when freed from alcohol and water, was subjected to elementary analysis. 

 •2619 gr. substance gave -5287 gr. C0 2 and 1930 gr. H 2 



Found. Calculated for C 8 H 14 4 . 



C . . . 5506 per cent. 55*17 per cent. 



H . 819 „ 805 



The oil had thus the composition of diethyl succinate. It boiled at 213° (uncorr.): the 

 boiling-point of succinic ether is 216°. 



On saponification with alcoholic potash it yielded a potassium salt exhibiting all the 

 reactions of a succinate. The silver salt obtained from the potassium compound by 

 precipitation was analysed for silver with the following result : — 



•1878 gr. substance gave "1215 gr. Ag . 



Found. Calculated for Ag 2 C 4 H 4 4 . 



Ag .... 647 per cent. 65"0 per cent. 



The acid itself, prepared from the silver salt, melted at 180°, the fusing-point of succinic 

 acid. 



To establish completely the identity of our synthetic acids, we have had recourse to 

 the valuable method proposed by Ostwald, which consists in determining their electric 

 conductivity at different stages of dilution, and calculating from the values so obtained 

 the very characteristic dissociation-constant. The apparatus employed was that described 

 by Ostwald in the Zeitschrift fur physikalische Chemie, vol. ii. p. 561. The letters used 

 in the tables have the following signification : — v is the number of litres of the 

 solution in which one molecular weight of the acid in grams is contained ; fx is the mole- 

 cular conductivity in mercury units at 25° ; 100m is the quantity per cent, of acid dis- 

 sociated into its ions ; and finally k is the dissociation or affinity-constant calculated 



9 



on 

 according to the equation k = IOOtt— — r- . m^ denotes the molecular conductivity in an 



infinitely dilute solution, and m is calculated from the formula w = . 



* Freund, Berichte d. deut. chem. Ges., xvii. 780, 1884. 



