WATER ANALYSIS 41 



(2) Standard solution of ammonium chloride, such that 

 1 c.c. = o-oi mgr. NH 3 . Ammonium chloride, NH 4 C1, 

 has a molecular weight of 53-5, of which 17 parts are due 

 to ammonia NH 3 . Since the standard solution is 1 c.c. = 

 o-oi mgr. of ammonia, 1 litre will contain o-oi grm. of 

 ammonia. 



17 : o-oi : : 53-5 : x = 0-03147 grm. of NH 4 C1 will yield 

 o-oi grm. of ammonia. Hence, dissolve 0-03147 grm. of 

 ammonium chloride in 1 litre of ammonia-free distilled 

 water, and 1 c.c. will contain o-oi mgr. of ammonia. 



Process. Take a retort or boiling-flask of about 700 c.c. 

 capacity, cleanse it well and rinse it out with ammonia- 

 free distilled water. Now put into it 200 c.c. of ammonia- 

 free distilled water, connect to a condenser, start the water 

 flow in latter, and distil over 100 c.c. to rid the apparatus 

 of any traces of ammonia. Test the distillate with Nessler's 

 solution, and if ammonia is found in the last portions, 

 repeat the distillation. If not, cool flask, wash out with 

 ammonia-free water, and proceed. 



Introduce into flask 500 c.c. of sample water and render 

 this alkaline by the addition of some recently-heated 

 sodium carbonate. Connect to a condenser, start the water 

 supply for the latter, and place a clean 50 c.c. Nessler glass 

 at the end of the condenser to catch the distillate. Make 

 sure that all parts of the apparatus are properly connected 

 and adjusted. Now apply the flame of a Bunsen burner 

 to the flask, which may be protected by a piece of gauze. 

 Heat gently at first, but once the parts have got heated, 

 increase the flame. Try to distil over at the rate of 50 c.c. 

 every fifteen minutes. When the first Nessler glass is 

 filled to the 50 c.c. mark, remove it and put another clean 

 one in its place, and so on. Have a stock of six ready for 

 the purpose. 



The first 50 c.c. of distillate is then tested by adding to 

 it 2 c.c. of Nessler solution and mixing. Place the glass 

 on a white slab, or on the glass shelf of a Nessler stand, 

 and on looking down through the liquid, the amount of 

 coloration produced, or its absence, is easily made out. 

 With experience the depth of colour will suggest how 

 much standard solution will be required to match it. 

 The next step is to put up three trial glasses for comparison. 



