CHAPTER CXL. 



WATER ANALYSIS. 



'T^HE farmer should be careful about the quality of the 

 water he uses for irrigation or drinking purposes. The 

 presence of nitrates is helpful for vegetation, but that of 

 nitrites and of chlorine indicates sewage contamination, and 

 nitrites are also injurious to crops. 



1.436. Distillation is the only means of getting chemically 

 pure water. Even rain water, which is the purest of all 

 natural waters, contains traces of chlorides, ammonia, nitrates 

 and particles of arsenic and other solid bodies, such as baci- 

 lli, meteoric dust &c. For obtaining 8 gallons of distilled 

 water 10 gallons of ordinary water should be used. This 

 should be distilled from a copper still connected with a 

 block tin worm. The first half gallon of distilled water is 

 to be rejected and the next 8 gallons kept. 



1.437. l n testing the purity or adaptability of water, the 

 following points should be noted: (i) Total Hardness; (2) 

 Permanent Hardness ; (3) Chlorine (4) Nitrates and Nitrites ; 

 (5) Free Ammonia; (6) Albuminoid ammonia and (7) Total 

 Residue after distillation. The points which a farmer 

 should specially note are Chlorine, Nitrates' and Nitrites. 



(i) Total hardness represents the whole amount of lime 

 and other salts which render water hard. Clarke's soap 

 test is applied for determining total hardness. 50 c. c. of 

 water are taken in a stoppered bottle of about 200 c. c. 

 capacity. A burette is filled with the standard soap solution, 

 and, i c. c. added each time and the bottle shaken. When 

 the lather remains permanently for 5 minutes further addition 

 of the solution should be stopped and the number of c. c. of 

 the solution used read off. Then from the " Table of Hard- 

 ness " the proportion of CaCOs in 100,000 parts of water^ 



