NITROGEN. 87 



Experiment 5. Mix about equal weights (10 grammes of each) of ammonium 

 chloride and calcium hydroxide (slaked lime) in a flask of about 200 c.c. capa- 

 city, and arranged as in Fig. 8 ; cover the mixture with water and apply heat. 

 As long as any atmospheric air remains in the apparatus, bubbles of it will 

 pass through the water contained in the cylinder; afterward all gas will be 

 readily and completely absorbed by the water. Notice the odor and alkaline 

 reaction on litmus of the ammonia water thus obtained. When the gas is 

 being freely liberated, move the tube upward, as shown in B, and collect the 

 gas by upward displacement in a cylinder or tube, which when filled with gas 

 is held mouth downward into water, which will rapidly rise in the tube by 

 absorption of the gas. Notice that ammonia is not readily combustible, by 

 applying a flame to the gas escaping from the delivery tube. 



Ammonia is a colorless gas, of a very pungent odor, an alkaline 

 taste, and a strong alkaline reaction. In pure oxygen it burns, form- 

 ing water and free nitrogen. 



By the mere application of a pressure of seven atmospheres or by 

 intense cold ( 40 C., 40 F.), ammonia may be converted into a 

 liquid, which at 80 C. ( 112 F.) forms a solid crystalline mass. 

 Water dissolves about 700 times its volume of ammonia gas, forming 

 ammonium hydroxide : 



NH 3 + H 2 O = NH 4 OH. 



For analytical reactions of ammonia, see Ammonium compounds. 



"Water of ammonia, Aqua ammonise (Spirit of hartshorn). This 

 is a solution of ammonia gas in water or ammonium hydroxide in 

 water. The common water of ammonia contains 10 per cent, by 

 weight of ammonia, and has a specific gravity of 0.96 ; the stronger 

 water of ammonia, aqua ammonice fortior, contains 28 per cent., and 

 has a specific gravity of 0.901. Ammonia water has the odor, taste, 

 and reaction which characterize the gas. 



Compounds of nitrogen and oxygen. Five distinct compounds 

 of nitrogen and oxygen are known. They are named and constituted 

 as follows : 



Composition. 



By weight. By volume. 



NO NO 



Nitrogen monoxide, N 2 O ... 28 16 2 1 



Nitrogen dioxide, N 2 O 2 = 2(NO) . . 28 32 2 2 



. Nitrogen trioxide, N 2 O 3 ... 28 48 2 3 



Nitrogen tetroxide, N 2 O 4 = 2(NO 2 ) . 28 64 24 



Nitrogen pentoxide, N 2 O 5 ... 28 80 2 5 



The first, third, and fifth of these compounds are capable of com- 

 bining with water to form acids, known as hyponitrous, nitrous, and 

 nitric acid, respectively. 



