CAPILLARY ACTION 99 



The first thing to note is the extremely rapid rise of water 

 in the two coarser soils, a height of 8-9 inches being reached 

 during the first hour, while the water in the two stiffer soils 

 had only reached ii-2 inches. The first soil,has a very simple 

 constitution, very little clay or silt being mixed with the sand ; 

 the rise here is nearly completed in the first day, and is 

 quite finished in six days. The second soil contains hardly 

 any more clay than the first, but there is a good deal of silt, 

 which, occupying the interspaces between the sand, entirely 

 alters the behaviour of the soil to water. At the end of 

 the first day the water has risen to nearly double the height 

 reached in the first soil. After six days the rise becomes 

 very slow, and getting slower and slower, a height of 

 47 inches is finally reached in 125 days, 42 days having 

 been consumed in accomplishing the last inch. The rise 

 of water in the silty soil is at first much slower than in the 

 two previously mentioned, but the rate of progress is well 

 maintained, and 50 inches is finally reached in 195 days. 

 The heavy adobe soil is for a long time far behind the 

 others, but like No. 3, it goes on when the others have 

 stopped, and the water at last reaches 46 inches in 195 days. 

 The rise of water in clay soils is thus very slow, and the 

 considerable height finally reached is no proof of energetic 

 capillary action. The colloid ingredient of the clay is doubt- 

 less a hindrance to the rapid passage of water, though perhaps 

 helping finally to carry the water to a greater height. 

 Capillary action is most active in the case of the alluvial 

 soil, made up of fine sand and silt ; in soils of this class, more 

 than in any other, will this action be of substantial benefit 

 to a crop. 



At the close of the experiment the percentage of water 



H 2 



