74 THE PHYSICAL PROPERTIES OF SOILS 



FIFTEENTH EXERCISE 



THE SPECIFIC HEAT OF SOILS 



The specific heat of a body is the ratio between the 

 amount of heat necessary to raise a given weight of 

 the substance one degree, and the amount necessary 

 to raise the temperature of the same weight of water 

 one degree. The specific heat of dry soil is usually be- 

 tween 0.20 and 0.30, but this is greatly modified by 

 the presence of moisture, the wetter the soil the larger 

 the quantity of heat required to raise the temperature 

 a given number of degrees. 



APPARATUS FOR THE DETERMINATION OF THE 

 SPECIFIC HEAT OF SOILS 



The apparatus consists of a double-walled cylin- 

 drical heater (AJ made of heavy copper, and connected 

 to a steam-system. Extending through the heater 

 is a hollow core (C), open at both ends, but provided 

 with movable covering at either end. The calori- 

 meter consists of a polished brass cup (E) of about 

 500CC. capacity, supported on corks and insulated from 

 outside influences by means of an air space (F) and 

 an outer jacket (G) of wood and felt. The lid to the 

 outer jacket is also covered with heavy felt and carries 

 a thermometer graduated to tenths of degrees. 



The calorimeter is mounted on a sliding base, which 

 permits it to be brought under the heater at the proper 

 moment to receive the heated sample. 



METHOD OF DETERMINATION 



Determine the specific heat of a sand and of a 

 clay soil, first in the dry state and then in a moist 



