268 Dr. Thomson on the [Oct. 



.jp^^^th part of the whole, and the whole perplexity vanishes, 

 and the numbers resume that simplicity and accordance with 

 each other which marks a law of nature. 



If there be any person who has a reluctance to yield his 

 assent to the above conclusions, and to admit that the specific 

 gravity of sulphur vapour and of oxygen gas are precisely equal, 

 1 flatter myself that the following observations will remove his 

 remaining doubts. 



In the year 1803, I demonstrated by a set of conclusive expe- 

 riments that the oxygen in sulphurous acid is precisely two- 

 thirds of the oxygen in sulphuric acid.* This conclusion is 

 now universally admitted by every chemist without exception. 

 Let us now observe the gradual progress of the attempts made 

 by chemists to determine the exact composition of sulphuric 

 acid. Sulphuric acid is composed, according to 



Sulphur. Oxygen. 



Lavoisier, of 100 + 40-845 



Chenevix, of 100 + 62-601 



Bucholz, of 100 + 135-300 



Klaproth, of 100 + 136-190 



Richter, of 100 + 138-100 



Berzelius, of 100 + 146-85 



Ditto, by later experiment, 100 + 148-44 

 Thomson, from the specific 



gravityof sulphurous acid, 100 + 149-9925 



In these results it is obvious that there is a constant approach 

 towards 150 as the quantity of oxygen united to 100 of sulphur. 

 Indeed in the last result deduced from the specific gravity of 

 sulphurous acid gas, as stated in this essay, the oxygen is only 

 ■To-oo-oth less than 150. Is it possible for any one that considers 

 the above series of results with attention not to conclude that 

 the true composition of sulphuric acid is 



Sulphur 100 



Oxygen 150 



Even Berzelius has advanced considerably towards this pro- 

 portion. His first experiments gave him sulphuric acid 

 composed of 



Sulphur 100-00 



Oxygen 146-85 



His last experiments, made on purpose to correct the former 

 ones, gave him the acid composed of 



Sulphur 100-00 



Oxygen 148-44 



• Nicholson's Jounial, yi. 98. 



