248 GASEOUS BODIES. 



volumes represent an atom, while 1 volume of 

 the second set of gases represents an atom. Thus, 

 when we wish to combine 1 atom of sulphurous 

 or carbonic acid with 1 atom of ammonia, we 

 must mix 1 volame of the acid gas with 2 vo- 

 lumes of the ammoniacal gas. 



Protoxide 4. The constitution of protoxide of chlorine 

 ofchiorme. is Different from that of both the preceding sets 

 of gases. It is composed (if Davy's experiments 

 be accurate) of 4 volumes of chlorine, and 2 vo- 

 lumes of oxygen gas, condensed into 5 volumes. 

 We obtain its specific gravity by adding together 

 four times the specific gravity of chlorine gas, 

 and twice the specific gravity of oxygen gas, and 

 dividing the sum by five ; this gives us 2'4444 

 for the specific gravity of this gas. As it is a 

 compound of 1 atom chlorine and 1 atom oxy- 

 gen, its atomic weight is obviously 5*5. Now, 

 the specific gravity of this gas is obtained by 

 multiplying its atomic weight by 0*4444, which 

 is fths of the specific gravity of oxygen gas ; for 

 5-5 x 0-4444 == 2-4444. The reason of this is 

 obvious from the peculiar condensation which 

 the constituents of this gas undergo when they 

 combine. 



5. Olefiant gas has not been inserted in the pre- 

 ceding tables ; it has been reserved for separate 

 notice, on account of the peculiarity of its na- 

 ture. Its specific gravity is 0'9722 ; and it is 

 obvious, from the phenomena of its combustion, 



