982 



Mr. Gervaise Le Bas on the 



two substituents acts in the direction of causing curvature 

 o£ the C chains where this is necessary. 



X-CH 2 -CH 2 -CH 2 -X 



^ 



CH 2 

 / \ 



CH 2 CH, 



X 



That attractive forces of sufficiently powerful nature are 

 possible, is seen from the fact that all the unsaturated 

 groups possess latent valencies, e. g., Cl, Br, I, OH, as also 

 N0 2 , NH 2 , COOH. 



It is apparently necessary for the unsaturated groups to- 

 be singly linked to the carbon atoms, so as to possess sufficient 

 mobility. Doubly linked atoms lack this mobility and thus 

 do not contribute to the constitutive effect. We find an 

 example in : 0. 



Groups like CH 3 — , C 2 H 5 — , CH 3 — , are usually supposed 

 to be saturated, but probably are not so. The attractive 

 force might not be sufficiently powerful to change the con- 

 figuration of hydrocarbon chains, but two such groups in 

 proximity would doubtless attract each other. 



This subject can only be adequately dealt with, when a more 

 extended body of data is available. 



The configurations of the compounds thus are : — 



Ethylene dichloride. 



Propylene Glycol. 



Ethylene bromide 



CH 2 — Cl 



I - !! 



CH 3 - CH — OH 



I J! 



CH 2 — Br 



1 '* 



1 '! 

 CH 2 - Cl 



1 

 CH 2 - OH 



CH 2 - Br 



Contraction 



A... -3-1 



-3-13 



-3-2 



Trimethylene bromide. 



Trimethylene Glycol. 



Trimethylene chloride.. 



CH 2 - Br 

 CH 2 || 

 ^CH, - Br 



CH 2 - OH ~ 

 / " 

 CH 2 

 v \ !! 

 CH 2 - OH 



CH 2 — Cl 



y ii 



CH 2 



\ i: 



CH 2 — Cl 



A -4-8 



-4-3 



-5-0 



Chlorethylene dichloride. 



Tetrachlorethane. 



Pentachlorethane. 



Cl ~ CH - Cl 



i :: 



Cl - CH - Cl 



ii , ii 



i 1 II 



Cl-C Cl-Cl 



II . 11 



1 ss 



CH 2 -C1 



Cl - CH - ci 



II II 



Cl - CH - Cl 



A -3-3 



-6-0 



-5«6 



