168 



NON-METALS AND THEIR COMBINATIONS. 



cium. Usually ammonium chloride is mixed with calcium hydroxide 



and heated, when calcium chloride, water, and ammonia are formed : 



2(NH 4 C1) + Ca(OH) 2 = CaCl 2 + 2H 2 O + 21s T H 3 . 



Experiment 6. Mix about equal weights (10 grammes of each) of ammonium 

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

 ity, and arranged as in Fig. 39; cover the mixture with water and apply heat. 



FIG. 39. 





Apparatus for generating amuioiiia. 



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, at its freezing-point, dissolves as much as 1050 volumes of 

 ammonia gas, and at 15 C. (59 F.) still retains 727 volumes of the 

 gas in solution. This solution contains ammonium hydroxide : 

 NH 3 + H 2 = NH 4 OH. 



Certain experimental evidence indicates that only a small propor- 

 tion of the gas is combined with water to form hydroxide, most of it 



