294 HISTORICAL INTRODUCTION TO CHEMISTRY CHAP. 



oxygen, and the relative weights of the two elementary 

 atoms are as i : 7, nearly. 



(2) That ammonia is a binary compound of hydrogen 

 and azote, and the relative weights of the two atoms are 

 as i : 5, nearly. 



(3) That nitrous gas is a binary compound of azote and 

 oxygen, the atoms of which weigh 5 and 7 respectively ; 

 that [nitrogen peroxide] l is a binary or ternary compound 

 according as it is derived, and consists of one atom of azote 

 and two of oxygen, together weighing 19 ; that nitrous oxide 

 is a compound similar to [nitrogen peroxide], and consists of 

 one atom of oxygen and two of azote, weighing 17. .. 



(4) That carbonic oxide is a binary compound, consisting 

 of one atom of charcoal, and one of oxygen, together 

 weighing nearly 12 ; that carbonic acid is a ternary compound 

 (but sometimes binary) consisting of one atom of charcoal, 

 and two of oxygen, weighing 19; etc., etc. In all these 

 cases the weights are expressed in atoms of hydrogen, each 

 of which is denoted by unity" (A.C.R. II. 30-31). 



Dalton's atomic symbols. Much of the success of 

 Dalton's atomic theory was due to the system of symbols 

 which he introduced (A.C.R. 11.32), to represent the atoms 

 of elements, and the molecules of compounds. Typical 

 examples were : 



Dalton's Berzelius's 



Atoms. Symbol. Symbol. 



Hydrogen .... Q H 



Azote (J) N 



Carbon .... @ C 



Oxygen .... Q O 



Sulphur . . . S 



Dalton's Berzelius's 



Molecules. Symbol. Symbol. 



Water OO II + O 



Ammonia .... ^^CD H + N 



1 "Nitric acid" in the original. 



