PRACTICAL AGRICULTURE. 208 



absorbs from the atmosphere. Peats and clays possess 

 this power ia the highest degree. The absorbing 

 power of other soils — those neither peaty nor clayey 

 — forms an important means of estimating their value. 

 Sir Humphrey Davy found that 1,000 lbs. of soils of 

 various qualities absorb in an hour as follows : 



A very fertile soil from East Lothian, - 18 lbs. 



A fertile soil in Somersetshire, - - - 16 " 



A soil worth 453., - - - - - 13 " 



A sandy soil worth 28s., - - - - 11 " 



Coarse sand worth los., - - - - 8 " 



Heath soil worth Httle or nothing, - - 3 ** 



By means of this absorption of water during the 

 night, a portion of the moisture, which plants lose by 

 perspiration in the day-time, is restored to them 

 through their roots. 



POWER OP CONTAINING "WATER. 



386. If we put different soils upon a fine strainer, 

 previously saturated with water, and then let water 

 fall upon them, drop by drop, till it begins to run 

 through and fall below, we shall find that some will 

 contain a much larger amount of water than others. 

 According to Prof Johnson, 106 lbs. 



Of dry quartz sand will hold - - - 25 lbs. 



Of calcareous (limy) sand, - - - - 29 " 



Of loamy soil, 40 " 



Of English chalk, 45 « 



Of clay loam, 50 " 



Of pure clay, ------ 7o " 



Of a peaty soil, ------ still more. 



