54 AIR AND FIRE 



phosphorus, the volume of water that enters the jar, and, therefore, 

 the volume of the oxygen, will be about one fifth of the volume of air in 

 the jar at first. 



Nitrogen made in this way contains argon, a gas even more inactive 

 than nitrogen itself. Argon makes up almost one per cent, by volume, 

 of air. 



Perhaps the most convenient way to get a 250 c.c. bottle 

 of nitrogen is to heat carefully a solution of 5 g. of sodium 

 nitrite and 5 g. of ammonium chloride in 100 c.c. of water. 

 The nitrogen escapes, and is collected over water. 



55. Properties of Nitrogen. Unlike oxygen, nitrogen 

 does not unite readily with other substances, and does 

 not support burning and life. It dilutes the active oxygen 

 of the air. Nitrogen is somewhat lighter than the air, 

 and is very slightly dissolved by water. Like oxygen, it is 

 colorless, tasteless, and odorless. 



Nitrogen finds it hard not only to unite with other 

 substances, but also to hold its place in many substances 

 that contain it. As a result of this property it is made a 

 part of all our common explosives, such as gunpowder, 

 nitroglycerine, guncotton, etc. These are all substances 

 that hold nitrogen loosely. When the explosive is set on 

 fire, or is given a " shock" (cf. 24), the nitrogen is set 

 free as a gas under great pressure, and in expanding does 

 the work required of the explosive. 



56. Nitrogen and Life. The properties and uses of 

 nitrogen described in preceding sections are due to the 

 fact that it has little activity, or little power of uniting 

 with other substances. But nitrogen is important also 

 because of certain positive qualities : it forms a necessary 



