700 



vestigation to find sometliing about the type of the pseudo-system, 

 wliieli is, of course, a far nioie difficult problem. 



2. The test may now take i)lace in different ways: 



a. by an inquiry into the influence of the previous treatment on 

 the poini of solidification, resp. melting point, point of transition etc. 



h. by an inquiry into the influence of the previous treatment on 

 the solubility. 



c. by an inquiry into ihe influence of the previous treatment on 

 the specific gravity, the viscosity, the index of refraction, the specific 

 heat, and further on every other property of the substance. 



(/. by the study of any temperature function, in which a con- 

 firmation of the said theory may follow from the way in which 

 this function varies with temperature. 



Besides in this way the theory of allotro[)y can probably also be 

 tested in another way, by the fact that as I observed already before^) 

 it may be expected that the different kinds of molecules of a same 

 substance will in general differ in reactive power. 



On that occasion I already pointed out that by means of this the 

 passivity of the metals might be explained, hence also the permanent 

 or periodic changes in the potential difference between metal and 

 electrolyte, in the solution of some metals by an electrolytic way, 

 so that when this view should prove correct, a new means would 

 have been found to prove the complexity of the metals in the 

 study of the phenomenon of passivity brought about by a purely 

 chemical or by an electrolytic way. 



As I am of opinion that the experiment really shows the validity 

 of the above mentioned supposition, I will expound here further 

 how the electrolytic deposition and solution of metals must be con- 

 sidered in the light of the theory of allotropy, and at what conclu- 

 sions we then arrive. 



3. When we have a metal that shows the phenomenon of allotropy, 

 different kinds of molecules will be present in this metal. To simplify 

 the matter as much as possible, let us assume that molecules M^ 

 occur by the side of mon-atomic molecuhis M. When this metal is 

 immersed in an electrolyte and emits ions, two different kinds of 

 ions will be emitted; if the metal as ion, carries three positive charges 

 per atom they will be the ions M" and M^-'- on the supposition made. 



Up to now it has always been assumed that a metal emits only 

 one kind of ions, now the theory, however, states that when one 

 of the coexisting phases is in internal equilibrium, the other must 



^) These Proceedings, May 3i, 1913, XVi, p. 191. 



