Optical Isomerism, and the King -Electron, 43? 



the mass of each radicle and the distance of its centre of 

 gravity from the centre o£ figure of the tetrahedron as all 

 that need be considered — a view which could not be held at 

 the present time ; but Orum Brown assumed merely " that 

 there is a function, capable of numerical representation, 

 derivable from the composition and constitution of the 

 radicle and the temperature of the substance, and that it is 

 the difference between the values of this function in the case 

 of two radicles which gives us the difference of character 

 referred to." According to the present theory, it would be 

 the values of the magnetic and electric fields produced by 

 the radicles which would determine the degree of asym- 

 metry. 



Amongst the papers read at the discussion on " Optical 

 Rotatory Power." held before the Faraday Society in 1914, 

 one of the most interesting from a theoretical standpoint was 

 that by Leo Tschugaeff. He came to the conclusion that 

 the electrons which are most active in producing rotation are 

 attached to the asymmetric carbon atom itself , or are situated 

 ia the immediate neighbourhood of the centre of activity. 

 As regards the other electrons which come into plav in 

 rotatory dispersion, we can assume that their activity is 

 diminished with increasing distance from the asymmetric 

 complex. Again, if it be admitted that the decree of 

 asymmetry of the molecule depends upon the differences of 

 four constants K 1? K 2 , K : >, and K 4 , corresponding with the 

 four groups attached to the carbon atom, the value of the 

 unknown function K must depend on the degree of satura- 

 tion. '• Thus, it would be expected that strongly unsaturated 

 radicles containing free-movable electrons would exert a 

 considerable influence on the electric field produced bv the 

 molecule, the differences K^— K 2 . . . being much larger if 

 K 2 corresponds with a saturated group and K, to an un- 

 saturated one than if both the groups are nearly equally 

 saturated." 



The present theory is in general agreement with the views 

 just described, but the equation representing the views of 

 Gruye and Orum Brown would require some modification. 

 Since the rotatory power as well as the dispersion is assumed 

 to be equal to the sum of the effects produced by the several 

 active electrons, as is expressed by the formula 



it is necessary to consider the contributions from the four 

 pairs of electrons associated with the four attached groups. , 



