267 



have onlj' to apply tlie theory of allotropy, i.e. we have to 

 assume that every phase of tliese substances contains at least two 

 different kinds of molecules, which are of course in inner equili- 

 brium in the case of unary behaviour, to which we add the supo- 

 sition that at least one of these kinds of molecules is chemically 

 inactive. This is very well possible, wince the mechanism of the 

 transformation into another type of molecule will be an intirely 

 different one from thai of chemical action with other substances. 

 To represent the case as simply as possible we can then assume 

 that there are only two different kinds of molecules, one of which 

 is active, the other inactive. When for ammonia we denote them 

 by NH,« and NH,;i, we have in each phase in the case of unary 

 behaviour, the following inner equilibrium: 



My supposition was this that on intensive drying tliis inner 

 equilibrium is shifted towards the inactive side, and in this case, 

 completely, so that in the ammonia remains that only contains the 

 inactive kind of molecules. 



I will just mention here that I emphatically pointed out before 

 that the expression "different kinds of molecules" should be taken 

 in its widest sense. It should comprise not only the isomer and 

 polymer molecules, but also the electrically charged dissociation products, 

 ions -\- electrons, and it stands to reason that in many cases the 

 difference between the different kinds of molecules lies in adilference 

 in the atomic structure. 



li is particularly the more recent views of atomic structure that 

 have brought to light that between the different atoms very subtle 

 differences are possible, which are e.g. in connection with a change 

 of tiie quanta values of the \alency-electi'on-paths, and this leads to 

 kinds of molecules with more subtle differences than those which 

 are assumed to exist between the ordinary isomers. The fact, however, 

 remains that also these different kinds of molecules may be ranged 

 under this category when the sense in which the idea "isomery" is 

 taken, is very wide. 



During my investigation there appeared a publication by Baty 

 and Duncan '), in which they communicate among other things that 

 the rapidity at which gaseous ammonia, withdrawn from an iron 

 cylindre with liquid ammonia, is decomposed by a platinum spiral 

 heated at a definite temperature, is dependent on the velocity of 

 evaporation of the liquid ammonia. On rapid evaporation ammonia gas 



1) J. Chem. Soc. 121 en 122, 1008 (1922). 



18 

 Proceedings Royal Acad. Amsterdam. Vol. XXVI. 



