1C2 lIO-\V CKOPS FEED. 



Fine carbonate of lime 35 



Heavy clay soil, (80 per cent clay) 41 



Garden mold, (7 per cent liuraus) 53 



Pure clay 49 



Carbonate of mai::ncsi;i (fine jiowder) 83 



Humus 130 



Davy found that one tliousnnd parts of the soils named 

 below, after having been dried at 212°, absorbed during 

 one hour of exposure to the air, quantities of moisture as 

 follows : 



Sterile soil of Bagshot h^ath 3 



Coarse sand 8 



Fine sand 11 



Soil from Mersey, E.-sex 13 



Very fertile alluvium, Somersetshire 16 



Extremely fertile soil of Ormiston, East Lothian 18 



An obvious practical result follows from the ficts ex- 

 pressed in the above tables, viz.: that sandy soils which 

 have little attractive force for watery vapor, and are there- 

 fore dry and arid, may bo meliorated in this respect by 

 admixture with clay, or better with humus, as is done by 

 dressing with vegetable composts and by green manuring. 

 The first table gives us proof that gypsum docs not exert 

 any beneficial action in consequence of directly attracting 

 moisture. Humus, or decaying vegetable matter, it will 

 be seen, surpasses every other ingredient of the soil in 

 absorbing vapor of water. This is doubtless in some de- 

 gree connected with its extraordinary porosity or amount 

 of surface. How the extent of surface alone may act is 

 made evident by comparing the absorbent power of car- 

 bonate of lime in the two states of sand and of an im- 

 palpable powder. The latter, it is seen, absorbed twelve 

 times as much vapor of water as the former. Carbonate 

 of magnesia stands next to humus, and it is worthy of 

 note that it is a very light and fine powder. 



Finally, it is a matter of observation that " silica and 

 lime in the form of coarse sand make the soil in which 

 they predominate so dry and hot that vegetation perishes 



