130 



On the Influence of Atomic Arrangement. 



Phenyl oxide 



C,H 6 .b.C,H, 



m.p. =28°. 



C 6 H 5 .S.C 6 H 5 



Liquid. 



Diphenyl 



C 6 H 5 . C 6 H 5 



m.p. = 70°. 



is more symme- 

 trical than 



more symme- 

 trical than 



Oxydiphenyl. 



c 6 h 5 .c 6 h/.oh 



m.p. = 164°. 



C 6 H 5 .C 6 H 4 .SH 



m.p. = 110°. 



is more symme- 

 trical than 



Acenaphthalene. 



,CH 2 



Cio H 6 \ i 



m.p. 



CH 2 



95°. 



Isomeric Pyrotartaric Acids. 



CH 



(l) 

 COOH 



CH 3 



^ 



COOH 



170° 



(2) 



COOH 

 H-C-CH 3 

 CH 2 

 COOH 



(3) 



COOH COOH 



\ / 



CH 



CH 2 



CH 3 



(4) 



COOH 

 CH 2 



CH 2 

 CH 2 

 COOH 



m.p. 



lll c 



m.p. =5 



m.p. = 112°. 



No. 4, which is more symmetrical than No. 2 and No. 3. is less 

 compact; and perhaps this is the cause of the low melting-point. 

 Bayer has shown that, if we compare the melting-points of 

 homologous series, we find that the melting-point is materially 

 influenced by odd and even numbers, in such a way that those 

 compounds containing an even number of carbon atoms melt 

 higher titan the neighbouring compounds containing an odd 

 number, thus: — 





Melting 



-point. 





Melting 



-point. 





Even. 



Odd. 





Even. 



Odd. 



CH 2 2 





8-6 



C 2 H 2 4 



200 





C 2 H 4 2 



+ 17 





C 3 H 4 4 



... 



132 



C 3 H G 2 





b.-21 



C 4 H 6 4 



180 





C 4 H 8 2 



+ 1 





C 5 H 8 4 





97 



C 5 H 10 O 2 





b. — 10 



C« H (0 O 4 



148 





C 6 H 12 2 



-2 





C 7 H 12 4 





103 



C 7 H u 2 





-10-5 



C 8 H 14 4 



lib 





C 8 H 16 2 



+ 16 





C 9 H 16 4 





106 



C9 H 18 2 





+ 12 



C10 H ]8 4 



127 





C10 -f^o C 2 



+ 30 





Cn H 20 4 





108 



Ci6 H 32 2 



+ 62 





Cn H 32 4 





132 



C n H 34 2 





+ G0 









Ci8 H 36 2 



+ 69 



[To be coi 



itinued]. 







