xvn MOLECULAR ARCHITECTURE 447 



displaceable by radicals, but was not then convinced that 

 marsh gas contained only one atom of carbon. Kekule's dis- 

 covery of the carbon-skeleton as the basis of all the hydrocarbon 

 radicals provided a final solution of the problem of the molecular 

 structure of organic compounds ; in the fatty-compounds the 

 carbon-skeleton is composed of open chains of carbon atoms, but 

 in benzene and aromatic compounds derived from it Kekule 

 recognised, in 1865, the existence of a closed chain or ring of 

 carbon atoms. 



