250 PHYSICAL PROPERTIES OF SOIL. 



soil be wet enough to freeze. It is well known, that if, by 

 frost, the nature of the soil is thus changed, that if it is 

 ploughed while wet after freezing, the labor of the fall 

 ploughing is lost. A lasting injury is done by ploughing 

 land too wet. 



297. In reference to the electrical relations of soil, the dry 

 sands are non-conductors, the clays weak imperfect conduct- 

 ors, they are in the negative state. Geine is always positive 

 towards the elements of soil. 



298. In whatever view we regard geine, it is the basis on 

 which rests the whole art of agriculture. It is this which 

 causes the great difference of soil. It is a difference of phys- 

 ical characters. The chemical characters are uniform. If, 

 then, geine is the soul of fertility, if it makes soil hot, cold, 

 wet, dry, heavy or light, the proportion and state in which it 

 exists in soil, becomes an agricultural problem of the highest 

 value. This would lead to chemical analysis. The lectures 

 in which the principles set forth in this book were explained, 

 terminated with a practical exhibition of the process of 

 analysis of soil. Having already greatly exceeded the limits 

 to which it was intended to confine these pages, the subject 

 of analysis, and several other topics, may be resumed at 

 some other time. 



