296 ORGANIC CHEMISTRY 



This criticism loses its force if we suppose that the separation into 

 ions takes place only under the immediate influence of the chlorine 

 with which the ammonia reacts. It has been pointed out by many 

 different authors * that a separation of atoms from each other must 

 occur either before or at the same time that they enter into com- 

 bination with other atoms. The only part essentially new in the 

 hypothesis proposed is that this separation is into positive and 

 negative parts and that the same atom may be sometimes positive 

 and sometimes negative. The idea of a dissociation which occurs under 

 the influence of a reacting substance appears to be implied in a part 

 of Professor Nef's discussion of methylene dissociation, but it is not 

 always clear whether he has in mind chiefly a dissociation of this 

 sort or one which is independent of the interaction of different com- 

 pounds. 



The thought that the same atom may be at one time positive and 

 at another time negative is related to the older electrochemical theory 

 which supposed water to be positive in acids and negative in bases. 



We assume, then, that in every combination of atoms each union 

 involves an attraction between the positive and negative electrons 

 which are associated with the two atoms that unite. In saying this 

 I do not lose sight of the fact that such a thing as attraction per se, 

 in the sense that one body can influence another at a distance with- 

 out an intervening medium, is apparently inconceivable. I think 

 of the attraction as probably caused by some motion of the electrons 

 which enables them to act on each other through the aid of the 

 ether. It is convenient, however, to speak of this effect as an attrac- 

 tion, since our conception of its real nature is, of necessity, very 

 vague. One advantage of the idea that the attraction of the electrons 

 is of a kinetic nature is that we may conceive of the same electron 

 as becoming positive or negative, according to the nature of its 

 motion. 



The common conception, at present, is that an atom which has lost 

 an electron becomes positive, while either the electron in its inde- 

 pendent existence or the atom to which it is attached becomes nega- 

 tive. So far as I am aware, it has not been pointed out that this 

 view leads to the conclusion that the same atom must, under different 

 conditions, have a different weight. Thus a bivalent copper atom 

 which has lost two electrons must weigh less than a univalent copper 

 atom, which has lost only a single electron. It is true that our meth- 

 ods of determining atomic weights are scarcely accurate enough to 

 detect differences of this order. The suggestion which is made is that 

 the electrons of two atoms which are united have motions which 

 correspond to positive and negative charges, respectively, and that 

 when the atoms separate these motions may be retained, or lost as 

 1 See Erlenmeyer, Jr., Ann. Chem. (Liebig), 316, 50. 



