74 THE KEACTIONS OCCURRING IN SOILS. IV. 



The average amount of chlorine in rain-water at Eothamsted 

 is about 2-0 parts per million. In drainage water from 

 60 inches of bare soil (equal, as is shown in the table just 

 given, to not quite half the rainfall) the average amount is 

 3 - 9 parts per million and is very constant. Nitrogen as ni- 

 trates in drainage water from the same soil varied from about 

 10 in winter to about 14 parts per million in summer, the 

 yearly average being 10' 7, or a loss of about 40K>. per acre per 

 annum. From unmanured wheat land the drainage water 

 contained as the average for the whole year 6'0 parts per 

 million of chlorine and 3'4 parts per million of nitrogen as 

 nitrates, the latter varying from 4'3 in winter to O'l in 

 summer. 



In manured (farm-yard) wheat land the average numbers 

 were 7' 3 for chlorine and 5'8 for nitrogen. 



From these numbers it appears that at Rothamsted the 

 amount of chlorine in the drainage water is almost exactly 

 equal to that supplied in the rain. From the results of a large 

 number of analyses of drainage water and well waters, War- 

 ington concludes that 4-4 parts of nitrogen as nitrates per 

 million is the average proportion in the drainage from culti- 

 vated land in the Rothamsted district. 



Deherain's experiments were commenced in 1892, His 

 method of observation was to use 20 large water-tight cases 

 2 metres square and 1 metre deep, each holding 4 cubic 

 metres, or about 5 tons of soil. These were filled with soil 

 and subsoil. Access was provided to one side by means of a 

 sunk path, so that the drainage water could be collected from 

 the bottom of the cases. The results obtained during the first 

 year were probably untrustworthy because of the increased 

 nitrification due to the trituration and aeration of the soil in 

 filling the cases. Reports as to the results are published 

 annually in the " Annales Agronomiques." The Grignon soil 

 is rich in organic matter and capable, if moist, of yielding 

 large quantities of nitrates. 



In the year March, 1896 March, 1897, the following re- 

 sults were obtained" : 



* Jour. Chem. Soc. 1897, abst. ii., 591. 



