266 



which ions the central halogen-atom then should be heptavalent. 



As long as no exacter data about the configuration of inorganic 

 salts are at our disposal, such applications of Werner's theory 

 are not much promising 1 ). 



However the idea that the optical inactivity of the solution 

 should be caused by a very rapid auto-racemisation during the 

 process of solution of the salt, is used by them in a very 

 suggestive way to explain the dimorphism of Na Cl O s , discovered 

 by Mallard 2 ). This author observed a second unstable modifica- 

 tion of the cubic salt, isomorphous with the rhombohedral 

 sodium-nitrate. If now NaNO s be supposed to be a racemic 

 compound, its rhombohedral crystals being pseudo-racemic inter- 

 growths of d-, and 7-forms of cubic symmetry, the ditrigonal 

 second form of sodium-chlorate found by Mallard, would then 



OH 



OHL 



OH 



o _ 







II. 

 Fig. K 



be the racemic form of this salt, and its transition-temperature 

 might be thought entirely comparable to the temperature at 

 which the racemic compound is resolved by spontaneous crystalli- 

 sation, just as this occurred in the case of sodium- ammonium- 

 racemate below its transition-temperature. 



Although the idea is quite original ; it can hardly be denied 

 that there is much artificiality in the application of the co-ordina- 

 tion-theory in such cases. Nothwithstanding this, one fact may 

 perhaps be brought to the fore, which .might support the above 

 mentioned view in some respects : the addition-compound of 

 ethyl-pip eridine and propyl-iodide (or of propyl-piperidine and 

 ethyl-iodide), i.e. the ethyl-propyl-piperidonium-iodide (mpt : 276 C) 

 which was studied by de Brere ton Evans 3 ), presents apparently 



1) Cf. The critical remarks of A. W. Stewart in his Recent Advances in 

 Physical and Inorganic Chemistry, London, (1912). p. 165, 173, etc. 



2) E. Mallard, Bull, de la Soc. Miner. 7, 352. (1884). 



s ) C. de Brereton Evans, Journ. Chem. Soc. London 71. 522. (1897). 



