88 Journal, of the Mitchell, Society [^January 



the color. Hale concludes ttat isorropesis is the cause of color 

 in the aromatic as well as the aliphatic series. In both series 

 he considers the two modifications that must always be "in statu 

 nascendi" to have actually been shown to exist. "The change 

 of linking therefore, that must accompany the transformation 

 of one into the other is certainly to be considered as the source 

 of the oscillations which give rise to the vibrations in the ether 

 of a free period corresponding to those in the visible region of 

 the spectrum and hence the development of color in the sub- 

 stance." 



The foregoing is in brief the most important of the theories 

 advanced in regard to color and its relation to structure. As 

 indicated by the great difference in the essential as well as in the 

 minor details of the theories, the subject is far from closed. 

 The field is intensely interesting and promises important 

 developments. 



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Berichte, 1900, 33, 666, 851, 3895. 



Annalen, 1906, 349, 333. 



Berichte, 1906, 39, 1073. 



Trans. Chem. Soc, 1887, 51, 152. 



Die Auxochrome, Ahrens' Vortrage, 1908, 12, 1. 



Popular Science Monthly, 1908, 72, 116. 



Cohens', Organic Chemistry, Vol. 2, 346. 



Chapel Hill, N. C. 



