ARTICLES 601 



In many cases, there is no semblance of an additive law, 

 as is well shown by the metallic oxides. Again, iron and 

 nickel are very magnetic, yet iron carbonyl (Fe(CO) 5 ) and 

 nickel carbonyl (Ni(CO) 4 ) are diamagnetic. 1 No explanation 

 of such effects is at present in sight, unless, perhaps, the effect 

 of chemical combination causes in special cases a redistribu- 

 tion of electron orbits, or possibly even an electron transfer, 

 so that the molecule as a whole acquires a zero magnetic 

 moment. Such does not appear to be the case, however, in 

 the non-conducting hydrocarbons, and here, probably, the 

 local magnetic force plays a predominant part (Part 4). 



Certain extensions of this work have been made, dealing 

 with the origin of spectral series and optical activity, the latter 

 being dependent upon right- and left-handed electron revolu- 

 tions. Lack of space prevents more than a mere reference to 

 these effects in the present article. 



Conclusion. — The satisfactory explanation of many difficult 

 points met with in stereo-chemistry and in connection with 

 the periodic law appears to be possible only by giving due 

 consideration to both the magnetic and electrostatic forces ; 

 the former predominating in some cases, the latter in others. 

 (See also A. L. Parson, Smithsonian Miscell. Collections, vol. lxv, 

 p. 1, 191 5, and I. Langmuir, Journ. American Chemical 

 Society, vol. xli, p. 868, 191 9.) In any case it is clear that the 

 magnetic forces cannot be ignored, even when the electrostatic 

 forces do predominate, and the complete theory has yet to 

 appear which shall give to these two types of force the relative 

 prominence which the experimental data demand. The 

 arguments which have been advanced show that the complete 

 theory must (1) account for the molecular structure of crystals 

 and the preservation of indivisable valencies as they are known 

 to the chemist ; (2) explain the close connection which exists 

 between orientations of the planes of cleavage and the deport- 

 ment of crystals in a magnetic field ; (3) be consistent with a 

 spacial distribution of directed valencies, such as are required 

 by stereochemistry ; (4) account for the additive nature of 

 the diamagnetic property in non-conducting compounds ; 

 (5) be consistent with the absence of dielectric hysteresis. 



1 A. E. Oxley, Proc. Cam. Phil. Soc, vol. xvi, p. 102. 



