36 ^ OF THE ATOMIC THEORY. 



atom at all, or at least I could not have applied 

 it to any of the bodies with which we are at 

 present acquainted. This consideration appears 

 to have induced several of the most distinguished 

 chemists, both in this country and in France, to 

 discard the teAn atom altogether. Thus, Dr. 

 Wollaston, instead of atom, employs the phrase 

 chemical equivalent, and Sir H. Davy employs 

 the term proportion. But I did not see any 

 reason for being so squeamish. The word atom 

 is more convenient, shorter, and more distinct 

 than any other word which I could think of. 

 And when it is understood to signify merely 

 integrant particle of the substance to which it is 

 applied, it cannot, I think, have any tendency to 

 mislead the reader. 



2. Mr. Dalton, in the account of his atomic 



theory, which he gave to the public at the end of 



the first volume of his New System of Chemical 



Philosophy, employs some terms which have 



gradually got into general use, and which there- 



B8n * l J tBr * fore require to be explained here. These terms 



explained, are binary, ternary, quaternary, &c. 



1 atom of A -|- 1 atom of B = 1 atom of C, a binary compound. 



1 atom of A -\- 2 atoms of B = 1 atom of D, a ternary 



2 atoms of A -f- 1 atom of B = 1 atom of E, a ternary 



1 atom of A -\- 3 atoms of B = 1 atom of F, a quaternary 



3 atoms of A -j- 1 atom of B = 1 atom of G, a quaternary, &c. 



Thus, protoxide of iron is a binary compound, 

 composed of 1 atom of iron + 1 atom of oxygen. 





