38 A UNIT IX AGRICULTURE 



large test tube or long bottle, cover with water, shake thoroughly and 

 set aside. Which soil is at the bottom? Which at the top? Make 

 drawing of tube. Compare with result.- of Kxeivise \'A. Dry some 

 of each kind of soil as in Exercise 1 I. Weigh very carefully about 

 the same amount of each, and put in separate beakers. (Each soil 

 should be pulverized after drying.) Pour water itfto each beaker 

 from a graduate containing a measured quantity, until the water 

 rises to the surface of the soil. Find how much water it takes in each 

 case, recording results as follows: 



Sand Clay Loam 



Volume of soil 



Volume of water added 



Per cent of air space 



The amount of water is the approximate measure of the air space. 

 Which soil contains the most air? Which least? 



Ex. 18. Temperature of Soils. 



Material: the three jars of soil set aside in Exercise 17. Into 

 each jar pour sufficient water to wet thoroughly. In each jar put a 

 thermometer so placed that the bulb is just below the surface of the 

 soil. Weigh each jar and set the jars close together in the window 

 and where the sunlight can strike fairly. Take the temperature and 

 weight of each jar at the same hour of the day on alternate days 

 for one week. Record the results as follows: 



Sand Clay Loam 



Weight first observation 



Weight second observation 



Weight third observation 



Temperature first observation 



Temperature second observation 



Temperature third observation 



Which soil shows the highest temperature? Which the lowest? 

 From which does the water evaporate most rapidly? From which 

 does it evaporate most slowly ? What is meant by a warm soil ? By a 



