112 IOWA ACADEMY OF SCIENCES. 



THE PREPARATION OF AMMONIA FREE WATER 

 FOR WATER ANALYSIS. 



BY J. B. WEEMS, C. E. GRAY AND E. C. MYERS. 



[Contribution from (he Department of A(jricuUural Chemistry, Iowa State College, No. J.] 



The preparation of water which will not give the yellow 

 coloration with Nessler's reagent is an important problem 

 in the analysis of water. Where the laboratory water sup- 

 ply contains a small quantity of ammonia, suitable water 

 for use in water analysis can no doubt be obtained by ordi- 

 nary distillation and collecting that part of the distillate 

 which is free from ammonia. The w^ater supply of many 

 laboratories will not permit of this ready method of pre- 

 paring ammonia free water. The distilled water must be 

 redistilled with sulphuric acid and potassium permanga- 

 nate to obtain a satisfactory water which will remain col- 

 orless when the Nessler reagent is added to it. This 

 method requires distillation in a glass flask and is sub- 

 jected to the usual degree of breakage and loss. 



Recently a method has been proposed for the prepara- 

 tion of water for water analysis which has the advantage 

 that redistillation is not necessary. The method is as fol- 

 lows: 



(1). "One or two liters of ordinary distilled water is 

 placed in a stoppered bottle and a little bromine vapor is 

 then poured into it. After shaking, the water should be 

 just perceptibly tinted and should give a blue coloration 

 when dropped on iodide and starch water. One drop of a 

 strong solution of caustic soda is now added and the bottle 

 again shaken and p aced aside for ten minutes. Finally, 

 one or two drops of a solution of potassium iodide are 



(1). Journal Society of Chemical Industry, 1890, p. 255. 



