86 THE POPULAR SCIENCE MONTHLY. 



plants from this source. In some cases the chlorine has also been de- 

 termined. The absorptive capacity of soils and subsoils for water and 

 ammonia has likewise been investigated. 



The quantity and composition of drain age- waters under various 

 conditions have been the subject of elaborate and extended experi- 

 ments for many years, and the results obtained are of the greatest 

 importance. 



In 1870 three " drain-gauges " were made, each having an area of 

 one thousandth of an acre, and inclosing the soil and subsoil in a 

 natural state of consolidation to the depth of twenty, forty, and sixty 

 inches, respectively. As the surface-soil in these gauges is kept free 

 from vegetation, and no fertilizers are applied, their drainage repre- 

 sents, in effect, that of a bare, unmanured fallow. In the separate 

 drains of the permanent wheat-plots facilities were provided for col- 

 lecting samples of drain age- water from soils growing crops without 

 manure, with barn-yard manure, and with a great variety of chemical 

 manures. 



Determinations of the nitrogen in rain-water were made at Rotham- 

 sted as early as 1846. The ammonia in the rain-fall for fifteen months, 

 in 1853-'54, was determined in the laboratory at Rothamsted, and 

 again in 1855-'56 by Professor Way. Dr. Frankland made analyses 

 of the rain-fall, and also of dew and hoar-frost in 1869-'70, since which 

 time a series of systematic investigations have been conducted in the 

 Rothamsted laboratory. 



A large number of samples of the drainage-waters from the experi- 

 mental wheat-field were analyzed by Dr. Voelcker, the able chemist 

 of the Royal Agricultural Society, and by Dr. Frankland, previous to 

 1875, while over thirteen hundred samples have been analyzed since 

 that time at Rothamsted. The drainage of the " drain-gauges," from 

 1870 to 1874, was analyzed by Dr. Frankland, and since that date it 

 has been systematically investigated at Rothamsted. 



A full report of these drainage experiments is given in an elaborate 

 paper "On the Amount and Composition of the Rain and Drainage- 

 Waters collected at Rothamsted," published in the last three numbers 

 of the "Journal of the Royal Agricultural Society" (1881-'82), which, 

 from its direct applications to questions of farm-j:>ractice, and the light 

 it throws upon the obscure subject of soil-exhaustion and on the econ- 

 omy of manures, is undoubtedly the most valuable contribution to 

 agricultural science that has appeared for many years. 



Experiments were made for several years with plants representing 

 the gramineous, the leguminous and other families, and also with ever- 

 green and deciduous trees, to ascertain the amount of water given off 

 during their growth. 



Observations on the character and range of the roots of different 

 plants, the relative development of leaf and stem, and their compo- 

 sition at various stages of growth, have been made in connection with 



