PRACTICE XIX 



DETERMINATION OF SPECIFIC HEAT OF SOILS 



Two students may work together ; a special soil may be 

 assigned to each group. 



Place about 100 g. of soil in each of the two large weighing 

 bottles (50 mm. in diameter and 45 mm. in height). 



This soil need not be weighed. 



Dry in oven for at least 24 hours with stopper out of bottle. 

 Replace stopper to prevent soil from absorbing moisture and 

 weigh when cool. 



Place in the water bath 1 or oven, which is kept at a constant 

 temperature by a regulator, for 24 hours. 



The water value of the calorimeter cup, stirrer, and thermom- 

 eter is determined. 2 



Place in the cup enough water accurately weighed, or very 

 carefully measured at about 15 C., to make the water value of 

 system and water added exactly 200 g. of distilled water. 



Close calorimeter with thermometer and stirrer in place. Stir 

 and read the temperature of water until it becomes constant. 

 Record this temperature. 



Remove the cover, quickly take the weighing bottle from the 

 oven or water bath, remove stopper, and pour soil into calorim- 

 eter cup quickly but gently, to avoid splashing of water. Close 

 calorimeter with stirrer and thermometer in position. Stir the 

 mixture and read its temperature at half or minute intervals 

 until the temperature becomes constant. Record this temperature. 



Weigh the weighing bottle with any adhering soil. The differ- 

 ence between this and the weight of bottle and soil is the exact 

 weight of soil used. 



To find the specific heat equate the gain of heat by the water 

 against the loss of heat by the soil. 



It may be well to determine specific heat of the soils with a 

 definite proportion of water added (say 15 to 25 per cent). 



1 The Dr. Lillie water bath made by the Spencer Lens Co., or any oven in which 

 the temperature may be kept constant. It should be so arranged that opening the 

 door to remove or put in soils will have a minimum effect on the temperature of the 

 soils already in the oven. 



2 Weigh the cup and calculate its water value from the specific heat of the material 

 of which it is composed. Do the same for that part of the stirrer and thermometer 

 which will be immersed in the mixture. These weights must be estimated from the 

 total weight of stirrer and thermometer. 



40 



