448 AGRICULTURAL ANALYSIS 



and nitrites, is determined directly and alone. The error of the 

 determination is as small as nesslerizing admits of, since it is 

 possible, if necessary, to distil until the full amount of ammonia 

 is obtained. 



The determination of nitric nitrogen, in a given sample, by 

 the above method gave a mean quantity of product of 0.162 part 

 per million, while the determination, in the same sample, by the 

 modified schloesing method, gave 0.125 part per million. This 

 result confirms the supposition that in the complete evaporation 

 necessary to the manipulation of the schloesing method there is 

 a loss of nitrogen. 



387. Nitrogen in Rain Water. The amount of nitrogen as 

 nitrates and nitrites in the rain water at Rothamstead, for the 

 12 months ending April i, 1888, was found, by the schloesing 

 method, to be 0.614 pound per acre, the total rainfall being 21.96 

 inches. For the year ending April i, 1889, by the copper-zinc 

 method, it amounted to 0.917 pound per acre, the total rainfall 

 being 29.27 inches. The amounts found in other localities are 

 quite different from the above, as, for instance, the mean of 

 seven stations in Germany for 13 years, beginning in 1864, shows 

 10.18 pounds of nitrogen per acre. The average amount for 10- 

 years at the observatory of Mont Sauris, near Paris, shows 

 12.36 pounds of nitrogen per acre. The average for three years 

 at Lincoln, as determined by Professor G. Gray, shows 1.6 pounds 

 of nitrogen per acre per annum. At Tokio, in Japan, Kellner 

 found, for one year, 1.02 pounds per acre. 



388. Determination of the Ammonia. The method used at 

 Rothamstead is to make one determination of ammonia in the 

 whole of the distillate obtained, the strength of which is regu- 

 lated by varying the amount introduced into the retort, so that 

 it shall be equal to about two cubic centimeters of the standard 

 ammonia solution. A 150 cubic centimeter cylinder is first filled 

 with the rain water, and 50 cubic centimeters of nessler reagent 

 added. The depth of tint indicates what quantity of rain water 

 will be required for distillation. This having been determined, 

 the appropriate volume of the rain water, provided it does not 

 exceed 600 cubic centimeters, is placed in the retort described' 



