24 PRACTICAL AGRICULTURAL CHEMISTRY [60 



b. Sulphates in Water.— It is very seldom that a 

 natural water contains sulphuric acid in the free state, but 

 most spring waters contain it in combination with lime or 

 magnesia. Add to portions of the different kinds of water 

 in three test-tubes a drop of hydrochloric acid and ten drops 

 of barium chloride. A cloudiness, which may require a few 

 minutes to form, shows presence of sulphuric acid. The dis- 

 tilled water contains no sulphate, whilst the other two con- 

 tain it in varying quantities, as shown by the milkiness. 



c. Carbonates in Water.— Half fill three small 

 beakers with specimens of the different waters and boil 

 each for twenty minutes. Pour out the water and notice the 

 deposit (if any) in each case. The deposit is due to car- 

 bonate of lime, which deposits when the carbon dioxide is 

 driven out of the water (42). If a few drops of a dilute 

 hydrochloric acid are added, the precipitated carbonate will 

 effervesce (195). 



d. Salt in Water.— Half fill three test-tubes with the 

 samples of waters as directed in the last experiment and 

 add a drop of dilute nitric acid and ten drops of silver nitrate 

 to each. The distilled water will not change in appearance. 

 That water which gives most cloudiness contains most 

 salt. 



e. Hardness of Water.— The presence of dissolved 

 salts of lime and magnesia in water causes the precipitation 

 of soap. Water which produces this result is termed ' hard/ 

 Salt (sodium chloride) if present in large amount will also 

 produce this result. 



Dissolve a shaving of soap in a little distilled water and 

 shake up a little of the solution with the three samples of 

 water previously placed in test-tubes. The distilled water 

 will immediately produce a lather and remain clear, whereas 

 the other samples will become turbid and produce no 

 lather until a larger quantity of soap solution is added. 

 The amount of soap solution necessary to form a lather is 



