ioo RELATIONS OF SOIL TO WATER 



contained in the soils at different heights in the columns was 

 determined with the following results : 



Water per joo of Soil at different heights 



1 in. 6 in. 12 in. 24 in. 36 in. 47 in. 



1. Sandy Soil ... 24-3 ... 14-2 ... 3-9 



2. Alluvial Soil ... 36-6 ... 35-0 ... 32-5 ... 21-4 ... 12-0 ... 4-3 



Thus the greater the height in the column, the smaller 

 is the quantity of water found. As we ascend, the wider 

 interspaces would be found unfilled, and at last the particles 

 will be merely coated with a thin film of water. The supply 

 of water at extreme heights is thus very feeble, and it may 

 well be doubted whether the gain of water at these elevations 

 is not due rather to the condensation of vapour rather than 

 to an actual ascent of liquid water. 



In all experiments made with dry soils the upward move- 

 ment of the water is retarded by the fact that air has to be 

 expelled from all the passages. Some dry soils are also 

 difficult to wet, the particles remaining obstinately coated 

 with a film of air ; this is frequently observed in the case of 

 dried marsh soils. 



The question whether the quantity of water raised by 

 capillary action in ordinary soils is sufficient to furnish 

 a substantial supply to field crops has been greatly elucidated 

 by the experiments made by King at Wisconsin. 



In the first experiment (Wisconsin 6th Rep., 203) the con- 

 ditions were made especially favourable to capillary action. 

 A cylinder 4 ft. in height and i ft. in diameter, which could 

 be supplied with water from below, was first partly filled 

 with water, and the fine sand from the Wisconsin subsoil 

 was then dropped in, each addition of sand being well 

 stirred in the water. A column of sand 4 ft. high was 



