FUNDAMENTAL CONCEPTIONS 197 



has been to determine on the basis of these ideas of valence the " con- 

 stitution" of the carbon compounds; we determine by methods 

 which are called synthetic, as well as by an exhaustive study of the 

 reactions of a given compound, what may be called the "architec- 

 ture" of its molecule, i. e., we determine how the various atoms of 

 carbon, nitrogen, oxygen, and hydrogen, etc., of which the substance 

 may be composed are joined together by virtue of their affinity units. 

 How much has been accomplished on the basis of these ideas during 

 the past forty-six years, and how beautifully and simply all the facts 

 known with regard to the almost countless carbon compounds are 

 thus explained, only those can fully appreciate who have a detailed 

 knowledge of the subject. Notwithstanding the large number of 

 workers in the field, it has often required more than a decade of 

 work to determine the molecular architecture of one single carbon 

 compound, and the question at times seriously presents itself whether 

 we must not reach our limitations in this respect. In any case one 

 point is deserving of especial emphasis : this idea of structure which 

 has been applied chiefly to molecules containing the element carbon 

 attributes to them a rigidity which is improbable from a purely 

 dynamic standpoint. 



The present system of organic chemistry is thus founded upon the 

 assumption that the valence of all the atoms of carbon, wherever 

 found, remains invariably four. In the earlier part of the last century 

 many attempts were made to isolate the hydrocarbon methylene, 

 C =H 2 , which must contain bivalent carbon. Dumas and Peligot tried 



H 



to obtain this substance from methylalcohol, H 2 C. by loss of 



OH 



H 



water. Perrot tried to isolate it from methylchloride, H 2 C 



Cl 



by dissociation into methylene and hydrogen chloride at high tem- 

 perature. Berthelot, Butlerow, Wurtz, and Kolbe also made many 

 fruitless attempts in this direction. As a final result of these repeated 

 and negative efforts, chemists finally became convinced that com- 

 pounds containing bivalent carbon could not be isolated, and the con- 

 clusion, therefore, that carbon was one of the few elements possessing 

 a constant valence became very general. 



There has, however, long existed one very simple compound of 

 carbon which does not adjust itself to this system, - - namely, the 

 inactive and poisonous carbon monoxide. If we assume the valence 

 of oxygen as two, then we have here simply a derivative of methylene 

 in which the two hydrogen atoms are substituted by oxygen, C=0. 



