Anntial Report of the Council. xliii 



Perhaps Berthelot's most important researches have been 

 his determinations of the heat changes accompanying chemical 

 reactions, both those of formation and of decomposition. These 

 researches led him to enunciate the principle that every chemical 

 transformation, completed without the aid of external energy, 

 tends to produce that substance or substances in the formation 

 of which the maximum evolution of heat occurs. 



We can only mention a few of the immense number of 

 problems attacked by Berthelot, e.g., the effect of the electric 

 "effluve" on gases (in which he discovered persulphuric acid) ; 

 the question of the fixation of nitrogen by plants which he 

 carried out in his ' Laboratoire de chemie vegetale ' at Meudon 

 near Paris ; the reactions of acetylene and of cyanogen. All 

 chemists too are indebted to Berthelot for his fascinating 

 volumes on the Greek Alchemists and the origins of Alchemy. 



Berthelot had many honours, but perhaps the award of the 

 Joecker prize to him by the Academy of Sciences in 1861 most 

 affected his life and work. In that year he made his romantic 

 marriage with Mile. Brequet — a union of the happiest kind, — 

 only to end in the greater romance of their united death. 



Berthelot was a rapid worker, and what he did he gave 

 at once to the world. Hence the immense number of his 

 published papers, and the occasional self-contradiction of the 

 investigator. He seldom, if ever, left Paris except to go to his 

 Vegetable Laboratory at Meudon, but he found time to serve on 

 many Scientific Commissions and to give most valuable services to 

 the Government and the Municipality. All work of an 'expert' 

 kind for manufacturers and patentees he resolutely refused. 

 How he acted as foreign minister forms part of the political 

 history of our time. 



Berthelot was a wonderfully effective lecturer : for not only 

 did he marshal his facts with precision, but his arguments were 

 lucid, and his sentences fell with a slow musical cadence de- 

 lightful to listen to. His old students are unanimous in their 

 appreciation of the affectionate regard he ever held them in - y 



