Lysimeter Experiments 89 



and filtered. The filtrate was neutralized with ammonium hydroxide and 

 then acidified with hydrochloric acid. Neutral ferric chloride was then 

 added in excess and the resulting precipitate was removed by filtration. 

 The excess of iron in the filtrate was then removed by precipitation with 

 ammonium hydroxide solution. This procedure for the removal of 

 phosphorus was found to be much shorter than the official method, in which 

 sodium acetate is recommended. 



The filtrate and washings from the ferric hydroxide precipitate were 

 concentrated to about 75 cubic centimeters and used for the determination 

 of calcium, according to the official method described in Bulletin 107 

 (revised) of the United States Bureau of Chemistry, page 15. The filtrate 

 and washings from the calcium precipitate were made up to 200 cubic 

 centimeters, one-half of which was used for the determination of mag- 

 nesium according to the official method described on page 16 of the 

 bulletin cited above, and the other half for the determination of 

 potassium and sodium bj'' the official method described on page 17 of 

 the same publication. 



methods for the chemical analysis of drainage water and 



rain water 



Total solids. — To determine the total solids in the drainage water and 

 the rain water, 100 cubic centimeters was evaporated to dryness in a 

 platinum dish on the water bath and the residue was dried to constant 

 weight at the temperature of boiling water. 



Ammonia. — Ammonia was determined by distilling 250 cubic centi- 

 meters of the water after it had been rendered alkaline with a saturated 

 solution of sodium carbonate. The distillate was examined by the well- 

 known Nessler method, described in Bulletin 31 of the United States 

 Bureau of Soils, page 30. 



Nitrates. — The nitrates were determined by the method described in 

 Bulletin 31 of the United States Bureau of Soils, page 39. 



Sulfates. — The sulfates were determined by the method described on 

 page 49 of the bulletin cited above. 



Bicarhonates. — The bicarbonates were determined by the method 

 described on page 58 of the same publication. 



Silica. — For the determination of silica, two liters of the water was 

 acidified with nitric acid and evaporated to diyness. To the residue 



89 



