CH. II.] 



THE ROOT. 



63 



Siliceous sand 

 Calcareous sand 

 Fine lime 

 Gypsum powder 

 Humus 

 Magnesia 

 Sandy clay 

 Loamy clay 

 Brick earth 

 Grey pure clay 

 Garden mould 

 Arable soil . 

 Slaty marl . 



Firmness 

 when dry. 











5.0 



7.3 



8.7 

 11.5 

 57.3 

 68.8 

 83.3 

 100.0 



7.6 

 33.0 

 23.0 



Adhesion to a square 

 foot of iron when wet, 



3.8 lbs. 



4.1 

 14.3 

 10.7 



8.8 



5.8 



7.9 

 10.6 

 17.3 

 27.0 



6.4 



5.8 



4.9 



The preceding observations and facts are appli- 

 cable to Jweing, an operation beneficial in conse- 

 quence of its loosening the soil, as much, or more, as 

 by its destroying weeds. Moisture abounds in the 

 atmosphere during the hottest months, and it is 

 absorbed and retained most abundantly by a soil 

 which is in the most friable state. Professor 

 Schluber found, that 1000 grains of stiff clay ab- 

 sorbed in twenty-four hours only thirty-six grains of 

 moisture from the air ; whilst garden mould ab- 

 sorbed in the same time forty-five grains ; and fine 

 magnesia seventy-six grains. Then, again, pulver- 

 izing the soil enables it better to retain the 



