32 HISTORY OF CHEMISTRY. [LECTURE III. 



Lavoisier, we shall appreciate the reformation introduced by 

 him into chemical science. The direction of chemical thought 

 was entirely changed, and the facts hitherto ascertained appeared 

 in a new light. It was necessary, in a sense, to translate them 

 in order to understand them, and as it was recognised that a 

 new language was required for their proper comprehension, 

 the need of a system of chemical nomenclature made itself 

 apparent. 



I pass over all the attempts which had been' made prior 

 to this period to secure a uniform mode of expression, as 

 these did not lead to any results worth mentioning, and as 

 they occurred during a period to which I can only slightly 

 refer. I wish, however, to mention that Bergman repeatedly 

 approached the French chemists with a view to securing 

 uniformity in the naming of substances. In 1782 Guyton 

 de Morveau, probably stimulated by Bergman's suggestions, 

 travelled to Paris, and laid before the Academy there a pro- 

 posed system of chemical nomenclature. This system con- 

 tained much that was new and good ; but it could not secure 

 the approval of the principal chemists of the period, as it 

 assumed the existence of phlogiston, which even at that time 

 was vigorously contested by Lavoisier. The latter afterwards 

 succeeded in convincing Guyton of the accuracy of his new 

 views. Guyton agreed to reconstruct his system, and in 1787, 

 in conjunction with Lavoisier, Berthollet, and Fourcroy, he 

 published the Nomenclature Chimique. As this system em- 

 bodies the principles and constitutes the basis of the chemical 

 nomenclature now employed, I cannot pass it by without men- 

 tion, and I shall therefore state at least its more important 

 features. In doing so, it will frequently be necessary to em- 

 ploy French words. For practically all of these there are exact 

 English equivalents. 



Substances are all divided into elements and compounds. 

 Amongst the former there are included all those substances 

 which could not then be further decomposed, and these are 

 classed under five headings. Of these headings the first em- 

 braces those bodies which are of very common occurrence, and 



