1 8 PRACTICAL AGRICULTURAL CHEMISTRY [43-44 



chalk will deposit as a white incrustation on the sides and 

 bottom of the beaker. Carbonate of lime exists in this 

 form in natural waters, and is called ' temporary hard- 

 ness ' (60 d). 



T — if 



Preparation and Properties of Ammonia 



43. Ammonia is generally prepared by heating together 

 slaked lime and ammonium chloride. Grind together in a- 

 mortar equal parts of ammonium chloride and slaked lime, 

 place a little of the mixture in a test-tube and heat it. 

 Notice the strong smell of the ammonia which is formed. 



44. To obtain larger quantities of the gas it is much 

 more convenient to prepare it from its solution in water. 

 If strong ammonia solution is warmed the gas comes off 



in a rapid stream. 



Set up the apparatus 

 shown in fig. 20, placing 

 a small quantity of the 

 strongest ammonia solu- 

 tion in the flask. Since 

 ammonia is lighter than 

 air it may be collected 

 by upward displacement. 

 To do this place a jar 

 over the evolution-tube 

 and warm the flask cau- 

 tiously. The gas will 

 ascend into the jar. Now 

 dip a glass rod into 

 FlG - 20 strong hydrochloric acid 



and hold it near the mouth of the jar. When the jar is full 

 the ammonia gas coming in contact with the hydrochloric 

 acid will form dense white fumes around the moist part of 

 the rod. Discontinue heating and remove the jar. 



