A DREAM OF FAIR HYDRONE 4 97 



are undoubtedly the most active ; and next to these come the 

 molecules of hydronol : the increase in the activity of water 

 as its temperature is raised may, in fact, be ascribed to an 

 increase in the proportion of hydrone and hydronol in the 

 liquid. As to the activity of the polyhydrones, it is possible 

 to form an opinion only on grounds of analogy. 



In the case of the polymethylenes, the activity diminishes 

 from ethylene to pentamethylene. Thus ethylene combines with 

 the greatest readiness with bromine and with hydrogen bromide : 



H..C = CH, + Br 2 =- BrCH 2 . CH.Br CH 2 =CH 2 + HBr = CH 3 . CH.Br 



The higher polymethylene rings remain unbroken when 

 submitted to the action of bromine; but the trimethylene ring 

 is without difficulty opened out by means of hydrogen bromide : 



CH., 

 /\ + HBr = CH 3 .CH 2 .CH,Br 

 H 2 C — CH, 



The tetramethylene ring is somewhat less readily ruptured 

 and the penta- and hexa-methylene rings are unaffected by 

 hydrogen bromide. 



Assuming that the configuration of the carbon atom is 

 tetrahedral and that the affinities act in the manner pointed 

 out above, the angle at which two affinities meet is i09°28'. 

 To account for the behaviour of the different polymethylenes, 

 von Baeyer has argued that if it be supposed that in the 

 formation of ethylene two affinities of the one carbon atom 

 become united with two "affinities of the other carbon atom, 

 the affinities would be forced from their normal angular posi- 

 tions into parallelism — that is to say, through an angle of 



I0Q°28' 



^— - = 54°24' ; but in the case of the higher polymethylenes 

 the distortion would be less — thus : 



CH 2 CH 2 



/\ /\ 



CH 2 H 2 C— CH 2 H,C CH 2 H 2 C CH 2 



CH 2 = CH 2 H.,C— CH 2 HC— CH, H,C— CH, H 2 C CH, 



\/ ' 



54°44' 2 4 °44' 9 °34' o 44 ' - 5 °i6' 



The general behaviour of the hydrocarbons under considera- 

 tion, however, is scarcely that of strained molecules, but rather 



