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



carbons. Of course, the greater part of the carbonic acid remained in solution. 

 Another experiment gave about 1 per cent, of oxygen. 



The electrolysed solution was acidified and extracted with ether. After the ether 

 had been distilled off there remained a yellowish syrup. This was distilled under 

 diminished pressure, when it separated into a solid and a liquid part, which could be 

 almost perfectly separated from each other by treatment with chloroform, in which the 

 solid part was very slightly soluble. 



Solid part. — The acid was converted into the barium salt, and this purified by 

 recrystallisation. A barium determination gave the following results : — 



01919 gramme of the salt (dried at 130°) gave 0*1773 gramme of Ba S0 4 . 

 Calculated for BaC 4 H 2 4 . Found. 



Ba . 54-59 54-35 



The acid prepared from this salt fused at 136°, and on combustion gave numbers 

 agreeing with the formula of maleic acid : — 



0'1235 gramme of the acid gave 0'1882 gramme C0 2 and 00400 gramme H 2 0. 



Calculated for C 4 H 4 4 . Found. 



C 4139 4155 



H . 3-46 360 



The solid portion, therefore, consisted of maleic acid. 



Liquid part. — The acid was neutralised with ammonia, and the ammonia salt pre- 

 cipitated with silver nitrate. The silver salt was white, and was soluble in boiling water, 

 from which it crystallised on cooling. 



01730 gramme of the dried salt gave 00793 gramme Ag. 



Calculated for AgC 6 H 7 4 . Found. 



Ag . 43-02 45-84 



The quantity of silver found is too high for ethyl-silver maleate, which is explained 

 by the fact that the liquid part, consisting essentially of ethyl-hydrogen maleate, still 

 contained some maleic acid, which crystallised out after prolonged standing. 



From ethyl-potassium citraconate we likewise obtained no synthetic product. The 

 solution became gradually dark brown, but no ethereal layer separated. 



It would therefore appear that from unsaturated acids with the ethylene union 

 between two atoms of carbon, one of which is combined with that carboxyl the hydrogen 

 of which is, in the ethyl-potassium salt, replaced by potassium, no synthetic products are 

 formed by electrolysis, but only simpler substances which may be regarded as oxidation 

 products of the anion. 



In order to ascertain whether unsaturated acids, in which the ethylene union is further 

 removed from carboxyl, are better able to resist the oxidising attack taking place at the 

 anode, we examined the ethyl-potassium allylmalonate. This salt, CH 3 CH : CHCOOC 2 H 5 , 



I 

 COOK 



