SOIL AND SOIL PREPARATION 37 



24. CONTENTS OF SOILS 



Object. To prove that there is water in soil. 



Apparatus. Any kind of soil, scales, a pan or earthen dish for 

 heating. 



Method. Carefully weigh any convenient amount of 

 soil and place it in a pan or evaporating dish. Set it in a 

 slow oven and let it remain there for several hours. Weigh 

 it from time to time and continue the drying process until 

 the weight becomes constant. 



Do not overheat the sample, for it is not desired to burn 

 up any of the organic constituents. 



After the weight has become constant, find the difference 

 between the first and last weighings, and this will be the 

 amount of water contained in the sample examined. 



Investigation. Examine various soils in this way and 

 find which contain most water. How do woodland soils 

 compare with roadside soils and garden soils ? How do sandy 

 soils compare with loam and clayey soils in water content ? 



25. CONTENTS OF SOILS 



Object. To find out the amount of mineral matter 

 and organic substance in a given specimen of soil. 



Apparatus. Same as in Experiment 24. 



Method. Proceed as before until all water has been 

 driven off. Then increase the heat so that all organic sub- 

 stances may be burned. When only ash and such other sub- 

 stances as will not burn are left, again carefully weigh the 

 specimen. The final weight will indicate the amount of 

 mineral matter in the specimen. How is the organic part 

 to be determined? 



