LECTURE III. 



CHEMICAL NOMENCLATURE TABLES OF AFFINITY BERTHOLLET'S 

 VIEWS CONTROVERSY REGARDING CONSTANT COMPOSITION. 



IT will readily be understood why a new era dates from Lavoisier, 

 and why the latter is designated the reformer of chemistry, if 

 we consider what were the theoretical views held before his 

 time, and what they were at the period of his death. 



Lavoisier lived to have the satisfaction of seeing his views 

 generally recognised, in France at least ; they gradually gained 

 ground also in England and in Germany, where his works 

 were translated, so that it may be justly said that phlogiston, 

 at the beginning of the present century, had disappeared from 

 scientific works. 



Lavoisier not only overthrew the old theory, but it is his 

 chief merit that he introduced a new one in its place, and it is 

 perhaps advisable to state here the most important heads of his 

 theory. 



1. In all chemical reactions it is the kind of matter alone 

 that is changed, whilst its quantity remains constant ; conse- 

 quently, the substances employed and the products obtained 

 may be represented by an algebraic equation in which, if there 

 is any unknown .term, this may be calculated. 



2. In the process of combustion the burning substance 

 unites with oxygen, whereby an acid is usually produced. In 

 the combustion of the metals, metallic calces are produced. 



3. All acids contain oxygen, united, as he expresses it, with 

 a basis or radical which, in inorganic substances, is usually an 

 element, but in organic substances is composed of carbon and 

 hydrogen, and frequently contains also nitrogen or phosphorus. 



If we contrast these three statements with the views of the 

 phlogistians, i.e., with the theories which prevailed prior to 



