2i8 ANALYSIS OF WATER 



have a capacity of 1-5 to 2 litres. Rubber stoppers 

 should not be used for closing the flask or for connec- 

 tions. If corks are used it is advisable to cover them 

 with clean tinfoil, and the side-tube from the flask 

 should reach down to the water-cooled portion of the 



'0 ^mmsBmm g^ 



Fig. 30. — Distillation apparatus for water analysis. 



inner condenser tube. The distillate is received in 

 Nessler glasses (Fig. 31), uniform cylinders 6 ins. in 

 height and ij ins. in diameter, made of perfectly 

 colourless glass, and having a graduation mark at 50 c.c. 

 capacity. Before commencing the estimation the whole 

 apparatus should be thoroughly cleaned by distilling 

 pure water through it, until no trace of any ammonia 

 can be detected in the distillate. 



Free or Saline Ammonia. — Five hundred c.c. of the 

 water to be examined are measured out and poured 



