I shall now pi-oceed to discuss the substances in which the cjclic 

 bond of benzene occurs. 



For benzene itself we find — =11,73, and for ail the substances 



in which this cyclic bond occurs, CgHg is smaller than would follow 

 from the saturate hydrocarbons. Of the substances in wdiich the 

 grouping of C and H occurs, as this is the case for hydrocarbons, 

 6 C alone would already have a value exceeding 12 or close to it. 

 So the question again rises for what special reasons the cyclic bond 

 of the 6 carbon atoms makes them smaller. Perhaps the closed 

 chain, the ends of which coincide, is the cause of this through the 

 mutual attraction of these ends. 



That the binding of C to C with 3 valencies could account for 

 this, may be doubted for the present. 



But whatever the cause may be — we shall assume CgHg =11,73 



for the cyclic binding, and take the former value for the atoms 



further entering the molecule, wliicli are grouped as in the saturate 



hydrocarbons. 



Ti 

 For diphenyl we find — = 24,17 ; it is, compared with benzene, 



Pk 



a little too great, or perhaps benzene is a little too small. By adding 

 2,76 to diphenyl we should get 26,93 for diphenyl methane whereas 



27,3 would follow trom — . Whether these differences are the con- 

 Pi- 

 sequence of our a u proximate calculation, or whether they have a 



real signification, 1 dare not decide. By the addition of Cff, to ben- 



Tk 

 zene 11,73 + 2.76 = 14,49 follows for toluine. whereas — vields 14.27. 



Pk " 



We find further: 



Xylene (o) for — the value 17,1, calculated from benzene 



Pk s -,7 25 



' 17 ' 

 (m) „ „ ,, „ 17,64, „ „ „ i 



(p) ,> jj J? J, 17, 2o, ,, ,, ,, 



'T" 



Mesitylene for — tlie vahie 19,3 , cak'ulared from benzene 20,01 



Durene „ „ „ „ 23,62, „ „ „ 22,77 



Cumene „ „ „ „ 19,74, „ „ ,, 20,01 



Oymene „ „ „ „ 22,78, „ „ ., 22,77 



From Cresol (0) =15,67 follows for - H + (0,H) the value 1,17. 

 If the two H cancel each other, we should have =: 1,17, whereas 



