Manchester Memoirs, Vol. Ixiv. (1920), No. 3 9 



far as the /3-halogen atom and whether the lability of the latter 

 atom is not consequent on the induced polarity of the a-hydro- 

 gen atom ; such a question awaits further experimental 

 evidence. Space does not permit of discussion of possible 

 phases of, or effects in, the above arrangement of atoms when 

 the halogen atoms in their turn exercise functions as " key- 

 atoms." 



It raav at this point be emphasised that while double (and 

 treble ?) bonds are highly effective when suitably disposed for 

 carrying on the influence of a " key-atom " over a long chain, 

 similar influences may often be traced, though as a rule less 

 clearly, in the entire absence of double bonds. Thus the 

 decided lability and latent " positiveness " of the hydrogen 

 atom noticed in the group 



H-C-C=0. 



+ - + - 



is also discernible in the group 



H-C-C-O- 

 + - + - 



for ethyl ether readilv yields a/3-d/chloro derivatives, and ethyl 

 alcohol condenses with certain aldehydes in virtue of labile 

 hydrogen in its methyl group. More evident is the combined 

 effect of two singly bound oxygen atoms homogeneously 

 arranged : — 



H-C-C< 



+ - + ^O- 



for the a-hydrogen atom of acetals is very easily substituted. 

 It may with confidence be anticipated that the corresponding- 

 hydrogen atoms in amines will prove to be similarly reactive — 



H-C-C-N< 

 + - + - 



In illustration of the wide application of the principles which 

 the writer conceives to be associated with atoms capable of 

 inducing or affecting intramolecular polarisation, reference 



