376 HISTORICAL INTRODUCTION TO CHEMISTRY CHAP. 



By the analysis of barium sulphite (Klassiker, XXXV, 18), the 

 composition of sulphurous anhydride was found to be 



Sulphur = 50'55% 

 Oxygen = 49 '45% 



i.e. sulphur : oxygen = I : i nearly. The weights of oxygen in 

 the two oxides were thus in the ratio 3 : 2 as deduced from Gay- 

 Lussac's volumetric analysis (p. 169). Berzelius found that when 

 barium sulphite was oxidised to barium sulphate, no excess of 

 baryta or of sulphuric acid was produced. The ratio of barium 

 to sulphur was therefore the same in the two compounds. The 

 ratio of oxygen in the acid to oxygen in the base was 2 : i for the 

 sulphites, as contrasted with 3:1 for the sulphates (Chemical 

 Proportions, p. 122). 



Taking the modern values for the atomic weights, the 

 empirical formulae of these compounds can be deduced 



at once. 



LITHARGE 



Formula PbO. 

 LEAD SULPHIDE = 



Formula PbS. 

 SULPHURIC ANHYDRIDE 



Formula SO 3 . 



Sulphur 

 I- 349 

 r 349 

 32-1 

 0*0420 

 i 



Oxygen 



i -9 7 5 grams 



1221 atoms 



16 



0-12 34 atom 

 3 atoms 



