270 Mr. Exley's Application of 



number of atoms in equal volumes, and oxygen is as much 

 entitled to the character of a simple gas as any of them : 

 hence, it is reasonable to conclude it is not an exception to 

 the rule, but this would require 16 for its atomic weight. 

 The following arguments appear to me decisive. 



1. Sulphurous acid is the sole gaseous product, when 

 sulphur is burnt in dry oxygen gas, and the resulting 

 volume is the same as that of the oxygen consumed. 



2. Carbonic acid is the sole gaseous product when carbon 

 is burnt in oxygen gas, and the resulting volume is the 

 same as that of the oxygen consumed. 



3. Steam is the sole gaseous product when oxygen is 

 burnt in hydrogen gas, and the resulting volume is the 

 same as that of the hydrogen consumed. 



4. Sulphuretted hydrogen is the sole gaseous product 

 when sulphur is burnt in hydrogen gas, and the resulting 

 volume is the same as that of the hydrogen consumed. 



Besides, these substances have all been obtained in the 

 form of gases and limpid liquids ; now the striking analo- 

 gies before us prove, that they are formed after the same 

 manner : but, in the opinion of all parties, the first two 

 contain three atoms each ; hence, the others contain three 

 atoms each, and 16 is the atomic weight of oxygen. 



Again, take sulphurous and hypo-sulphurous acids on the 

 one hand, and water and deutoxide of hydrogen on the 

 other; then, 1st. Sulphurous acid is formed by burning 

 sulphur in oxygen gas, and the volume of oxygen is not 

 changed ; and the new gas may be passed through red hot 

 tubes without decomposition : but, several substances 

 which have a strong affinity for oxygen, as potassium, 

 carbon, &c., decompose it: also by a slight pressure it 

 becomes a limpid liquid. 2nd. Hypo-sulphurous acid con- 

 tains twice as much sulphur as the sulphurous acid ; it is 

 easily decomposed, and cannot remain permanent at com- 

 mon temperatures. 



Now the same sentence, with scarcely any variation, may 

 be read for the analogous substances, water and the deut- 

 oxide of hydrogen, by merely substituting the names of 

 these compounds and their elements. But sulphurous 

 acid consists of two atoms oxygen and one sulphur, and 

 hypo-sulphurous acid of one of each, which ever view of the 

 subject be taken ; hence, water must be allowed to be two 



