281 



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 transit ion- temperature. 



Although the idea is quite original, it can hardly be denied, as was 

 already said, that there is much artificiality in the application of the 

 coordination-theory in such cases. Notwithstanding this, one fact 

 may perhaps be brought to the fore, which might support the 

 above mentioned view in some respect: 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 Brereton Evans 1 ), presents apparently 

 a case quite analogous to that of sodium-chlorate in so far, as it 



Fig. 173. 



Ethyl-pYopyl-piperidonium-iodide. 



can easily be obtained in enantiomorphous crystals of monoclinic 

 symmetry, both of which, however, give absolutely inactive so- 

 lutions here. The crystal- forms are reproduced in fig. i?j a and b\ 

 they have the symmetry of the group C 2 . 



Just as in the case of sodium-chlorate, it was here also noticed, 

 that when a few large crystals separated from the solution, these 

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

 were nearly always of the same kind, whereas a large crop of 

 small crystals generally consisted of both forms in about equal 

 numbers. 



Now in the case considered, there is indeed some probability, 

 that to the enantiomorphism of the crystalforms, corresponds a 

 real enantiomorphism of the atomic arrangement in the constituent 

 molecules : for, probably, we have to deal here with a derivative of 



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



