458 



SCIENCE PROGRESS. 



first must be assigned to the isomer which alone yields the 

 nitrile, according to the equation 



RCH 



II 

 NOH 



RC 



N 



+ 



H 



I! 

 OH 



In ring-compounds a similar isomerism, corresponding to 

 the cis-trans isomerism of the hydrophthalic acids, has been 

 observed. Thus Ladenburg attributes to coniine and iso- 

 coniine the formulae 



H 



H 



and 



H 



C 5 H ; 



H 



H 



H 



The isomerism of the kreatinines is probably analogous ; 

 here as well as with the coniines one of the chief distinctions 

 between the isomers is the difference in solubility of the 

 platinum double salts. 



With regard to pentad nitrogen it has already been ob- 

 served that, united to five different radicals, it causes optical 

 activity. When any two of the radicals are identical the 

 activity disappears ; but now another kind of stereomerism 

 may arise. Thus two trimethyl isobutyl ammonium chlo- 

 rides and two methyl diethyl amyl ammonium chlorides have 

 been formed. When the radicals are smaller this isomerism 

 does not occur ; thus there is only one trimethyl propyl and 

 one tripropyl methyl ammonium chloride, probably owing to 

 the mobility of the smaller radicals. 



The existence of the active isomers shows that in them 

 the atoms are not in one plane, and the existence of the 

 other isomers shows that an alkyl may occupy either of two 

 positions in a substituted ammonia. The inactivity when 

 two radicals are identical shows that these lie symmetrically 

 with regard to the rest of the molecule. A graphic repre- 



