the Constitution of Carbon Compounds. 107 



pying an intermediate position. To judge from the compara- 

 tively greater stability of the primary alcohols, an opposite 

 result might fairly have been looked for. — Here, again, I con- 

 tend that it is to the local accumulation of negative elements 

 that we must attribute the increased development of heat ob- 

 served in the formation of tertiary alcohols, &c. 



The peculiar behaviour of the amines may, I think, be ex- 

 plained on similar lines. 



Thomsen's observations on ethylene oxide and aldehyde are 

 also of great interest from this same point of view; they 

 clearly prove that these compounds are not only unsaturated 

 in the ordinary sense, but that they are actually to a con- 

 siderable extent unexhausted bodies. Retaining the formula 

 ordinarily assigned to ethylene oxide, I am inclined to think 

 that it is a direct consequence of the structure of the com- 

 pound — especially of the relation in which the single oxygen 

 atom stands to the two carbon atoms, that the affinities of the 

 oxygen atom — and probably of the carbon atoms likewise — 

 are far from being satisfied. And in the case of aldehyde, 

 whether the oxygen atom is or is not associated by two affinities 

 with the carbon atom, as ordinarily supposed, there can 

 be little doubt that any formula in which the oxygen atom is 

 represented as " fully combined " with the carbon atom is 

 more or less misleading ; meanwhile, therefore, it is advisable 

 to formulate the aldehydes as containing the radical C(0)H. 



The very low values found for the heats of formation of the 

 simpler cyanogen compounds would appear to furnish addi- 

 tional evidence in support of the view that the polyad nega- 

 tive elements are endowed with peculiarities which limit the 

 extent to which on entering into combination they can 

 mutually satisfy or neutralize their affinities. 



(30) Thomsen has contended, time after time, that his 

 results afford a solution of the problem which has of late 

 years very properly excited so much attention, viz. that of 

 the constitution of benzene. As pointed out in § 8, he 

 maintains that the six atoms of carbon in this hydrocarbon 

 are linked together by nine " single bonds," and not, in the 

 manner indicated by Kekule's well-known formula, by three 

 single and three double bonds. Although of opinion that we 

 cannot at present accept so absolute an interpretation of the 

 thermochemical data, I yet think that Thomsen's results, 

 taken together with all that is known of benzene, must be 

 held to prove that benzene is in no sense a compound of the 

 same order as an olefine ; and that Kekule's formula, if used 

 at all, must be literally interpreted as indicating that the 

 carbon atoms are held together by nine affinities, there being 



12 



