on the Physical Properties of Compounds. 129 



Melting- 

 point. 



Methyl hippurate (C 8 H 8 NO).COO.CH 3 805 



Ethyl „ (C 8 H 8 NO).COO.CH 2 .CH 3 60-5 



Butyl „ (C 8 H 8 Ts T 0).COO.CH 2 .CH 2 .CH 2 .CH 3 40-5 



/CHs ... 45-5 



Isobutylhippurate(C 8 H 8 NO).COO.CH 2 .CH^ H 



Isoamyl „ (C 8 H 8 NO).COO.CH 2 .CH 2 .CH( CH 3 27 ' 5 



CH 3 



It will now be necessary to make a few remarks in regard 

 to the examples which have been given in illustration of what 

 is thought to be a true connexion between atomic structure 

 and melting-point, and more especially as regards the influ- 

 ence of symmetry. It would, of course, be easy to support 

 any theory if we merely gave those examples which were 

 favourable and excluded all those which were adverse. This, 

 however, has not been done in the examples which have been 

 given above. For the purpose of this paper there were taken 

 quite at random somewhere about 300 cases to which the rule 

 of symmetry could be applied; and of these 278 were in agree- 

 ment with the rule, whilst 22 were exceptions ; the latter 

 amounted therefore to only 7 per cent., which proves that the rule 

 is of almost general application. Many of the exceptions may 

 possibly be due to the constitution or arrangement of the atoms 

 not having been correctly determined, and might thus on close 

 examination be shown to agree with the rule. 



The following are some of the most marked exceptions 

 included in the above 22, and which are undoubtedly real ex- 

 ceptions, since the constitution is known with a considerable 

 degree of certainty: — 



„ , I is more symme- 1 ™ ,-, 



Tolane j tricaltLi [ Phenanthrene. 



CH = CH CH = CH 



C fi H 5 .C = C.C 6 H 5 



.p. = 



HO C— C CH 



\ . / \ . / 



HC— C C— CH 



HC=CII 



m.p. = 100°. 



