Today I was reading a short note about the life of Lavoisier and discovered that Marat was his sworn enemy and probably he was indirectly responsible for his death at the guillotine.
Nabokov wrote about the French Revolution, the guillotine, Maratīs murder by Cora Day and  I donīt remember his ever mentioning Lavoisier.
This scientist showed that the ancient belief in the four elements ( water, air, earth and fire ) was unfounded, adding at least sixteen elements to the original four, then discredited as such.  Lavoisier also opposed Maratīs attempt at writing scientific papers on the subject of fire, and he rejected the formerīs theories about combustion and his re-introduction of the concept of the "phlogiston". 
Nabokov made an issue about these four elements in various different moments in ADA: 
1. Air: Demon died in an airplane accident;
2. Fire: Marina was cremated; 
3. Water: the drowning of Lucette ( no reference to Aqua, though ) .
For the fourth element VN added: "Earth awaits..."
Could anyone clarify the importance that these "four elements" have for Nabokov in relation to the special role that fire plays in almost all his novels? Is Lavoisier ever mentioned in Ada?    
 
I have another question to add. 
Lucette was often described as "red haired" like her father, whereas Demonīs children had "raven black hair".
I was reminded again of VNīs chess-board and began to wonder about the opposition reds and blacks. 
The "honor code" that demanded  of Van that he should never try to make love to Lucette has always perplexed me, since in almost all other matters concerning sex and  love Van didnīt show any special kind of moral restriction. Could a special rule of chess for  Reds & Blacks serve as an equivalent for this forbidding "honor code" ?
Jansy