Maiichester Memoirs, Vol. Ivii?. {1^14), No. 10. 5 



Dimroth and Kerkovius {Liebigs An., 1913, 399, 120) 

 thought a carbon molecule to consist of pentagons as 

 well as hexagons. 



Bragg {Proc. R. S. 191 3, A6101, studying crystalline 

 structures by means of a A'-ray spectrometer, advanced 

 a three-dimensional configuration for a molecule of 

 diamond. 



H. Meyer {Moiiats/i., 19 14, 35, 163) discussing the 

 the carbon " molecule," puts stress on the difficulty, if not 

 the futility of trying to define the chemical entity of the 

 three forms of carbon. 



Here we see that the number of suggestions varies 

 more with the number of investigators than the number 

 of allotropic modifications of carbon. 



Now keeping in mind the proposed fundamental 

 assumptions, let us follow the possibilities for such a 

 representation (;/ being the number of atoms in a carbon 

 molecule). 



The first class is noted by the poiver of free rotation 

 of the units (single atoms or groups) constituting the 

 carbon molecule. (See Fig. 4.) 



The second class is noted by the partial rigidity of 

 the molecule, owing to the two single bonds linking some 

 units. (See Fig 5.) 



The third class is noted by complete rigidity of the 

 molecule. (See Fig. 6.) 



Here we have before us the striking fact that any 

 possible formula for carbon will fall into one of these 

 three classes. These three distinct classes are remarkable 

 from the fact that they would account for the three modi- 

 fications of carbon, and suggest the possible formulae for 

 amorphous carbon, graphite and diamond. 



We may hope that the careful study of the compara- 

 tive reactivity, theory of strain, refraction and other 



