252 



Dr. Thomas Thomsons Observations 



In all these gases the calculated specific gravity comes 

 within less than f^^th part of the experimental, except 

 in the case of calomel, which, being a vapour, and requiring 

 a high temperature to keep it in the gaseous state, cannot 

 be expected to be determined with minute accuracy. 



II. Gases whose specific gravity = their atomic weight 

 x - 5555 or h the specific gravity of oxygen gas. 



Hydrogen, 



Azote, 



Carbon vapour, .... 



Chlorine, 



Bromine, 



Iodine, 



Mercury, 



Carbu retted hydrogen, 



defiant gas, 



Carbonic acid, .... 

 Carbonic oxide, .... 

 Chloro-carbonic acid, . 

 Protoxide of azote, . . . 



Cyanogen, 



Sulphurous acid, 

 Sulphuric acid (dry), . . 

 Selenious acid, .... 

 Iodide of mercury . . . 

 Corrosive sublimate, 

 Sesquiodide of arsenic, . 

 Proto-chloride of Antimony, 



In all the gaseous compounds of carbon, hydrogen, oxy- 

 gen and azote, anc 1 also in chlorine and bromine, and iodine 

 vapour, the specific gravities determined by multiplying 

 the atomic weight by 0-5555 almost coincide with the ex- 



* These specific gravities have been given in a preceding part of this paper. 

 f These specific gravities were determined by me in 1820. — See Annals of 

 Philosophy, xvi. 161 and 241. 



J Dumas Ann. de Chim. et de Phys., xxxiii. 346. 

 § Mitscherlich. — Poggendorff's Annalen, xxix. 217. 



