EXPERIMENT STATION BULLETINS. 



495 



by gravel, olay, loam and i>c'at. The spet-ific heat of the latter soil as 

 detenuined in this invesligalion, is very interesting because it is jus{ 

 about half as great as that given to it by some other investigators. 



In the above table is also shown the amount of heat generated by 

 the different soils when wetted. It will be seen that this quantity of 

 heat is considerable and becomes greater as the organic matter of the 

 soil increases. In this respect it follows the same law as the specific 

 heat. 



The slight difference in the specific heat of the different soils, as 

 shown above, points to the important conclusion that this property 

 plays an insignificant part in the heat relationships of these soils. 



TABLE 2.— SPECIFIC HEAT OF SOILS BY EQUAL WEIGHTS. 



SPECIFIC HEAT OF SOILS BY EQUAL VOLUMES. 



The next question that arises is what is the specific heat of these 

 same soils when considered from the standpoint of equal volumes. 

 Practically speaking it is the specific heat by equal volume that is im- 

 portant from the agricultural standpoint and not the specific heat by 

 equal weight. In the field it is the depth or volume and not the weight 

 that is heated that is important to the plant. 



The specific heat of a soil by equal volume can be obtained by multi- 

 plying its specific gravity by its specific heat by weight. The results 

 obtained by this process are shown in the following table: 



