28 SCIENCE PROGRESS 



methylene compounds do not necessarily imply the non- 

 tetravalency of a carbon atom.) 



iii. Carbon exists in three allotropic modifications. 



(Several new modifications suggested by Brodie, Berthelot, 

 Luzi, and others have been proved by Moissan and Le Chatelier 

 to be either compounds or solutions and mixtures of carbon 

 with some other element.) 



Having to deal with the combination of carbon with oxygen, 

 it is obvious that the knowledge of the mechanism of such a 

 combination must be of essential importance to us. It seems 

 there are two and only two possible hypotheses which can 

 explain the process : 



i. The carbon molecule disintegrates at the first instant into 

 single atoms, which combine subsequently with oxygen. 



2. Oxygen combines at the first instant with the atoms inside 

 the carbon molecule, next follows a disruption of the complex 

 and the formation of the known oxides. 



Which of these two hypotheses is the correct one ? Can 

 we reasonably suppose that by the mere presence of oxygen, 

 which has not yet reacted chemically, the carbon molecule falls 

 to atoms, which would imply at least the volatility of carbon 

 at a temperature below red heat ? 



I think the first hypothesis is, at least, improbable. Now, 

 what can be said about the second ? 



(a) It is in complete agreement with the most recent ex- 

 perimental evidence. 



(b) It is quite logical. 



(c) It explains facts. 



(d) It is the only one left. 



Accepting the second hypothesis we are immediately con- 

 fronted by a multitude of complexes, requiring in their turn a 

 clear conception of a carbon molecule. 



What is a carbon molecule ? 



Is it a formless mass of atoms in a chaotic state, or is it 

 organised similar to the assumed structure of carbon compounds ? 



Our assumption will be — organisation. 



Now, if carbon is always tetravalent. what is the constitu- 

 tional, or as Butlerow calls it, structural, formula for a carbon 

 molecule ? 



Not much work has been done up to the present in this 

 direction. 



