NOTE ON THE SPECIFIC VOLUMES OF AROMATIC COMPOUNDS. 411 



1°. Chlorine in (1) is in direct combination with carbon oftlie 

 nucleus, that in (2) with one in the side-chain. 



2°. There are four (CH) groups in (1), five in (2) ; in other 

 words, there are two side-chains in (1), and only one 

 in (2); 



o°. The carbon to which clilorine is combined in (1) is in its 

 turn directly combined with two other atoms of carbon, 

 while that to which chloinne is combined in (2) is only 

 combined with one other carbon atom. 



Such considerations as these make us hesitate very inuch Ijcforo 

 making a free application of the very imperfect knowledge we possess 

 at present regarding the relation between specific volume data and 

 the constitution of chemical compounds. 



It is true that the specific volume of camphor calrulated with 

 the use of constants, C = 10.5 & 11, 11 = 5.5, = 12.2 or 7.8, does 

 not agree with the experimental value, ])at this is simply because we 

 are ignorant of the law Avliich counects together the variation of the 

 specific volume of an element with its mode of coml)ination. It is 

 possible, for example, that tlie specific volume of carbon directly 

 combined with four <-tlier atoms of carbon may l)e considerably lower 

 tliaii 10.5 or 11.' and tlie almoriually low specific volume of camphor, 

 as actually observed, may be due to the existence in it of two or more 

 sucli carljoii atoms. The six formulae of camphor cjuoted by 

 ^\r. Kuharn represent ir as containing respectively 0, 0. 2, 1, 2 and 

 1 such carbon atoms, and it may possibly turn out that either the 

 formula (o) or the formida (5) correctly i-epresents its constitution. 

 Further theoretical speculations upon these points are more than 



* It may he rumarki'rl tliat tlie atomic volume of diamond calculated in the usual manner 



