GASEOUS BODIES. 247 



(3.) The constitution of ammoniacal gas is 

 analagous to that of the four gases just mention- 

 ed. It is composed of 1 volume of azotic gas, 

 and 3 volumes of hydrogen gas, condensed into 

 two volumes ; so that its specific gravity, instead 

 of being equal to the specific gravity of azotic 

 gas, added to thrice the specific gravity of hy- 

 drogen gas, is only half that quantity, or O59027- 

 Therefore, with respect to its atomic weight, its 

 bulk is also doubled. 



From what has been just stated, it must be 

 obvious, that in these five gases the specific gra- 

 vity will be obtained by multiplying the atomic 

 weight of each by O2777, or ith of the specific 

 gravity of oxygen gas. 



The following table exhibits the atomic weights 

 and specific gravities of these gases : 



ATOMIC WEIGHT. SPECIFIC GRAVITY. 



Ammoniacal gas . 2-125 0-59027 



Hydrocyanic acid vapour 3-375 0-9375 



Deutoxide of azote . 3-75 1-04166 



35 Muriatic acid . . 4-625 1 -28472 



Hydriodic acid . . 15-625 4-34027 



It is obvious that a volume of oxygen gas con- 

 tains four times as many atoms as a volume of 

 any of these five gases. When we compare these 

 five gases with each other, an atom may be sub- 

 stituted for a volume ; but when we compare 

 them with the gases in the preceding table, two 



Q4 



