418 



SCIENCE. 



[N. S. Vol. VIII. No. 19S. 



We are not alone in this inquiry, but Lob has 

 endeavored to find an answer in the experi- 

 mental way. To do this, he electrolyzed 

 phthalic acid, dissolved in alcohol (a little 

 sulphuric acid was added to increase the 

 conductivity) with a feeble current. The 

 latter was allowed to act for several hours, 

 and there resulted an almost quantitative 

 yield of phthalic anhydride. It is not sur- 

 prising that this chemist inclines to the 

 view of an intermediate anhydride forma- 

 tion, but he wisely says that this is only 

 demonstrable with acids, whose anhydrides 

 are very stable. 



In dealing with the electrolysis of free 

 acids we can scarcely assert that breaking- 

 down occurs, because the acid reappears as 

 such at the positive electrode. Graphically 

 represented we should have : 



2CH3COOH = 2CH3COO + H2 

 SCHs- COO + H2O = 2CH3.COOH + O. 



or 

 2CH3 COOH = 2CH3-COO + H2 



2CH3C00 = (CH3 00)2-0 + O 



(CH3 C0)j0 + HjO = 2CH3COOH. 



The first equation shows that oxygen 

 comes from the water, while in the second 

 it has its origin in the intermediate anhy- 

 dride formation. 



But let us follow Lob and with him sub- 

 stitute hydrogen sulphide for water, then 

 the equations just written would appear 

 thus : 



2CH3.COOH = 2CH3.COO + Hj 



2CH3.COO + HjS = 2CH3.COOH + S. 



or 



2CH3.COOH = 2CH3.COO + Hj 



2CHj.C00 = (CH3.CO)jO + O 



Ch' CO > O + HjS = CH3.COOH + CH3.COSH. 



What do these teach us ? 



1. If an intermediate anhydride is not 

 formed then the original acid will be regen- 

 erated and sulphur will separate. 



2. If the anhydride is produced an evo- 

 lution of oxygen will take place, and a 



molecule of a thio-acid will be obtained for 

 every molecule of the ordinary acid. 



An experiment was performed to test 

 these ideas. Very pure acetic acid was 

 reduced to a low temperature and in this 

 condition saturated with hydrogen sulphide. 

 It was electrolyzed, the gas being still con- 

 ducted into the solution. Not a particle of 

 sulphur separated at the anode, and the 

 solution contained thio-acetic acid. 



Two experiments, therefore, indicated 

 the formation of an intermediate anhydride. 

 However, other views are prevalent. Thus, 

 Schall entertains the opinion that a perox- 

 ide is first produced in the electrolytic de- 

 compositions of the class we are consider- 

 ing. He electrolyzed the alkali salts of 

 dithio-acids and obtained persulphides of 

 the acids : 



CH3.CSS 

 2CH3.CSS — = I 



CH3.CSS, 



and then the action ceased. It may be be- 

 cause the persulphides are so much more 

 stable than the corresponding peroxides. 

 Schall apparently has been confirmed and 

 indeed antedated in his views, for Bunge 

 in 1870 subjected thio-acetic acid and thio- 

 benzoic acid to electrolysis and obtained 

 acetyl disulphide and benzene disulphide, 

 'facts which,' the author remarks, 'justify 

 the conclusion that the compound group sep- 

 arating in the electrolysis of the thio-acids, 

 at the anode, is liberated as a complex.' 



Hamonet conducted an extensive series 

 of experiments with the alkali salts of the 

 fatty acids. Inasmuch as he worked upon 

 a much larger scale than his predecessors, 

 his conclusions are entitled to thoughtful 

 consideration. They are in substance : 



1. The equation expressing the decom- 

 position of salts of the fatty acids as intro- 

 duced by Kolbe cannot be regarded as 

 correct. Frequently, parafiBn hydrocarbons 

 are not obtained, or at least in very small 

 amounts. 



