SECOND PERIOD. 5y 



The discoveries of Cavendish on the decom- 

 position of water, had rendered necessary a new 

 nomenclature, distinguishing simple from com- 

 pound bodies, and indicating the elements of the 

 latter. This project, conceived by Guiton-Mor- 

 veaux, was adopted by Lavoisier and other 

 chemists , among whom was Fourcroy , and 

 executed with an exactness of method , of 

 which the sciences offered no example. But 

 though this nomenclature , in which every word 

 was the expression of a fact, greatly facilitated 

 the labour of becoming acquainted with the exist- 

 ing and possible combinations of matter , it was 

 still a new language ; which of all innovations is 

 the most difficult to introduce in practice. The 

 advantages of the new nomenclature were too 

 obvious to be denied ; but if it had been learned 

 only in books, it would never perhaps have be- 

 come universal. Fourcroy adopted it in his lec- 

 tures, and as his eloquence, in which the clearest 

 ideas were conveyed in the most precise and har- 

 monious diction, captivated the attention of his 

 hearers, his expressions remained imprinted on the 

 memory, and chemistry was no longer spoken of 

 but in the terms he employed. The same language 

 being used by the demonstrator, soon became fa- 

 miliar ; and to the lectures in the King's Garden is 

 truly owing the rapid progress of chemistry. 



