42 THE SCIENTIFIC PRINCIPLES 



nitrogen as nitric acid, and the chlorine, have been 

 determined. Some experiments have also been made 

 on the comparative absorptive capacity (for water 

 and ammonia) of different soils and subsoils. The 

 systematic investigation of the amount, and the 

 condition, of the nitrogen, and of some of the more 

 important mineral constituents, of the soils of the 

 different plots, and from different depths, is now in 

 progress, or contemplated. 



Almost from the commencement of the experi- 

 ments the rainfall has been measured — for more than 

 thirty years in a gauge of one-thousandth of an acre 

 area, as well as in an ordinary small funnel-gauge of 

 5 inches diameter. An 8-inch ' Board of Trade ' 

 copper-gauge is also now in use, commencing 

 January i, 1881. From time to time, the nitrogen 

 as ammonia (and sometimes as nitric acid), has been 

 determined in the rain waters. The chlorine has also 

 been determined in many samples. 



Three ' drain gauges/ also of one-thousandth of an 

 acre each, for the determination of the quantity and 

 composition of the water percolating, respectively 

 through 20 inches, 40 inches, and 60 inches depth of 

 soil (with its subsoil in natural state of consolidation), 

 have also been constructed. Each of the differently 

 manured plots of the permanent experimental wheat- 

 field having a separate pipe-drain, the drainage- 

 waters have been, and are frequently, collected and 

 analysed. 



The nitrogen existing as nitric acid, sometimes 

 that in other forms, and also some other constituents, 

 are, and for some time past have been, determined 

 periodically, in both the rain and the various drainage 

 waters. 



For several years in succession, experiments were 



