288 



configurations in space, notwithstanding their opposite rotations. 

 But if this chloro-succinic acid is transformed into malic acid again, 

 the last appears to be this time the dextrogyratory antipode. In 

 this process there must have occurred at least one inversion, as 

 the dextro- and laevogyratory malic acids have certainly enan- 

 tiomorphous configurations. It is, however, questionable whether 

 the inversion took place during the change of the malic acid into 

 the chloro-succinic acid, or during the transformation of the last 

 acid into the final dextrogyratory malic acid. Moreover, it is most 

 remarkable, that evidently the inversion is intimately connected 

 with the particular nature of the substance by which the chloro- 

 succinic acid is finally transformed into the malic acid', for if 

 silver-oxide or silver-carbonate be used for this purpose, the final 

 product is the dextrogyratory malic acid, while, when potassium- 

 hydroxide or ammonia be used in the reaction, the original laevo- 

 gyratory acid is reproduced. 



Quite independently of the question, as to whether or not a 

 rearrangement of the groups round the asymmetrical carbon-atom 

 takes place in the transformation of l-malic into d-chloro- 

 succinic acid, or in that of the latter into one of the enantio- 

 morphous malic acids, an "inversion" must obviously have occur- 

 red during the process. 



It is possible, as has been pointed out by several investigators 1 ), 

 to pass through a complete cycle of such changes, if the corresponding 

 reactions be only suitably chosen. As an example of this, the 

 following cycle may be mentioned: 



+ KOH 



] ft PM r\Cf \7YZl "tT\T\7 



& 



aspartic acid 

 laevogyratory 



laevogyratory 

 bromo-succinic acid 



PBr 



dextro gyratory 

 malic acid 



+ Ag 2 



laevogyr&tory 

 malic acid 



+ 



+ 



dextrogyratary 

 bromo-succinic acid 



+ KOH 



If laevogyratory aspartic acid be treated with nitrosyl-bromide, 

 it is changed into the laevogyratory bromo-succinic acid ; this, however, 



*) P. Walden, loco cit.; Journ. de Chim. phys., 9, 164, 176, (1911); A. Mac 

 Kenzie and G. W. Clough, Journ. Chem. Soc. London, 93, 811, (1908); 95, 777, 



