628 



SCIENCE 



[N. S. Vol. XXXIV. No. 



really applicable. Unfortunately such ve- 

 locities are so high as to be beyond our 

 powers of measurement. Tet it seems pos- 

 sible to seek and obtain an answer from 

 reaction velocities which are measurable. 

 One assumption must be made, but it seems 

 to me so inherently probable that few will 

 hesitate to make it. It is this: if a sub- 

 stance in a given solution has normal ac- 

 tivity with respect to one reaction, it has 

 normal activity with respect to all reac- 

 tions in which it can take part in that given 

 solution. Similarly, if a substance in a 

 given solution exhibits abnormal activity 

 vrith respect to one reaction, it will exhibit 

 abnormal activity with respect to all. 



Granting this assumption, we have then 

 to find a reaction in which either the ionized 

 or un-ionized portion of an abnormal elec- 

 trolyte is converted into a third substance 

 with measurable velocity. Such a reaction 

 exists in the transformation of ammonium 

 cyanate into urea in aqueous and aqueous- 

 alcoholic solutions, which was investigated 

 some years ago by myself and my collabo- 

 rators, and found to proceed at rates which 

 could easily be followed experimentally. 

 First of all comes the question : Is the urea 

 formed directly from the ions or from 

 the un-ionized cyanate? As Wegseheider 

 pointed out, it is impossible from reaction- 

 velocity alone to determine which portion 

 passes directly into urea, if the velocities 

 of ionization and recombination are in- 

 finitely greater than that of the urea-for- 

 mation, as is undoubtedly the case. Other 

 circumstances make it highly probable that 

 the ions are the active participants in the 

 transformation, but we may leave the ques- 

 tion open, and discuss the results on both 

 assumptions. 



Suppose, first, that the un-ionized cya- 

 nate is transformed directly into urea. 

 Then we have the successive reactions 

 NH,- -1- CNO' ^ NH,CNO -^ CO(NH,),. 



The slight reverse transformation of urea 

 into cyanate may for the present purpose 

 be neglected, as it in no way influences the 

 reasoning to be employed. 



If the un-ionized substance behaves 

 normally, then the conversion of the am- 

 monium cyanate into urea, when referred 

 to the un-ionized substance, will appear 

 unimolecular and obey the law of mass- 

 action: when referred to the ionized sub- 

 stance it will not appear to be bimoleculai 

 and will not obey the law of mass-action. 



Suppose, now, that the direct formation 

 of the urea is from the ions. Then we are 

 dealing with the actions 



NH.CNO ?± NH^- + CNO' -^ CO(NH,),. 



Again, let us assume the un-ionized sub- 

 stance to be normal. Once more, if the 

 transformation is referred to the non- 

 ionized substance it will appear as mono- 

 molecular; when referred to the ionized 

 substance it will not appear as bimolecular, 

 as it should if the mass-action law were 

 obeyed. 



It is a matter of indifference, then, so 

 far as the point with wliich we are dealing 

 is concerned, whether the ionized or the 

 non-ionized cyanate is transformed directly 

 into urea. If the non-ionized cyanate be- 

 haves normally the action when referred to 

 it will in either case appear to be strictly 

 monomolecular. 



If the ionized cyanate, on the other hand, 

 behaves normally, the reaction when re- 

 ferred to it will be bimolecular and normal ; 

 when referred to the non-ionized cyanate it 

 will not be monomolecular, and therefore 

 will be abnormal. 



The actual experiments show that 

 whether water or a mixture of water and 

 alcohol be taken as solvent, the reaction 

 when referred to the ions is strictly bimo- 

 lecular; when referred to the non-ionized 

 substance it is not monomolecular, i. e., 



