The Evolution of the Sciences 



The description of chemical species is not 

 the sole business of chemistry; a new branch is 

 growing up slowly and logically, which looks 

 for matter where it is really alive, that is to 

 say in chemical reaction. Physicists have 

 sometimes been reproached for " amusing them- 

 selves by weighing flies' eggs in cobweb scales; " 

 but whoever has seen a chemical reaction 

 an object on fire, an acid and a base reacting 

 cannot help opening his eyes and inquiring 

 the reason of all this disturbance and display 

 of energy, and what is happening behind these 

 appearances. Thus the study of reactions is 

 not the accessory but the very essence of 

 chemistry. 



Such is the idea which to-day is leading- 

 chemistry towards new fields. Certainly it is 

 not a new idea; it has occurred beyond doubt 

 to all who since the beginnings of chemistry 

 have witnessed matter in reaction. Boerhaave 

 even invented a word, affinity, to designate 

 the mysterious cause of chemical reactions, 

 while Bergmann, a little later, drew up tables 

 of affinity, on the supposition that the power of 

 combination of each body could be expressed 



36 ' 



