268 SOILS AND FERTILIZERS 



poses of comparison and no calcium hydroxide is added. After 24 

 hours examine the three beakers and note the influence of the cal- 

 cium hydroxid in precipitating the clay and clarifying the liquid. 



Experiment No. n. 



Properties of Rocks from which many Soils are Derived. 

 Study the laboratory samples of rocks and fill out the following 

 table : 



Comparative General vSoluble 



Rocks. Hardness. Color. Form. in HC1 



Feldspar .... 



Mica 



Quartz 



Granite 



Hornblende. . . 

 limestone . . . 



Experiment No. 12. 

 Form and Size of Soil Particles. 



(Note. Special directions for manipulating the microscope, 

 placing the material on the microscopical slide, and focusing will 

 be given by the instructor). 



Place on a microscopical object slide a small amount of soil, dis- 

 tribute it in a thin layer, as directed by the instructor, and examine 

 with a low power microscope. Observe the form and size of the 

 soil particles, distinguish the various grades of sand, silt and 

 clay, and make drawings of some of the particles. 



Experiment No. 13. 

 Pulverized Rock Particles. 



Examine with a low power microscope samples of pulverized 

 mica, feldspar, granite, and limestone. Note any similarity to the 

 soil particles examined in Experiment No. 12. 



Experiment No. 14. 



Reaction of Soils. 



For this experiment use peaty, mildly alkaline and clay soils. 

 Bring in contact with each soil, moistened with distilled water, 

 pieces of sensitive red and blue litmus paper. Note any changes 

 in color of the litmus paper and state what the results show. In 

 a similar way test the soil from your own farm . 



