58 THEORY OF VOLUMES. 



just double that of oxygen : therefore it is evi- 

 dent, that 100 cubic inches of sulphur vapour, 

 as it exists in sulphurous acid, are of the same 

 weight as 100 cubic inches of oxygen. Such 

 facts led to a new mode of ascertaining the 

 atomic weights of bodies, and threw much addi- 

 tional light on the ultimate constitution of matter. 

 For example, if sulphurous acid be composed of 

 2 atoms of oxygen to 1 of sulphur, it follows, that 

 the atom of sulphur must be just 16 times that of 

 hydrogen, and double that of oxygen. 



By pursuing this method of investigation, Dr. 

 Thomson arrived at the conclusion, that carbon, 

 oxygen, and sulphur, are even multiples of hy- 

 drogen without fractions (Records of Science, 

 March, 1836) ; whereas Berzelius makes the 

 atomic weight of carbon 0-76438 ; that of sul- 

 phur 2-01165; and sulphurous acid 4-01165, 

 compared with oxygen 100. 



ought to be deduced from analogy for example, if carbonic acid 

 consisted of equal volumes of carbon vapour and oxygen, he 

 maintains that they ought to combine without any condensation, 

 because in all other cases, when equal volumes of gaseous bodies 

 unite chemically, there is no contraction, as in binoxide of nitro- 

 gen, hydrochloric acid, hydriodic acid, &c. He thinks that con- 

 densation never takes place, unless the combining volumes are un- 

 equal ; therefore, that carbonic acid is composed of one volume of 

 oxygen to half a volume of carbon vapour, (the specific gravity of 

 which would be -832, instead of -416, or 12 times that of hydro- 

 gen.) But it is not very material whether we regard the specific 

 gravity of carbon vapour as 6 or 12 times that of hydrogen, as 

 either number is in accordance with the law of multiple ratios. 



