PRACTICE VII 



DETERMINATION OF THE REACTION OF A SOIL 



Each group of students will work upon one of a group of soils 

 selected by the instructor, using surface and subsoil samples. 



Place about 10 g. of soil in a Jena-glass flask with 100 cc. of 

 ammonia-free water, shake thoroughly several times, and allow to 

 stand over night. Draw off 50 cc. of the supernatant liquid, add 

 a few drops of phenolphthalein, and concentrate in a Jena-glass 

 beaker to about 10 cc., if a pink color does not develop before this 

 point is reached. 



To what is the development of a pink color in the solution due ? 



What is the condition of the soil when no color appears ? 



If no pink color develops, determine acidity as directed in Prac- 

 tice IX. 



If a pink color develops, determine the limestone present accord- 

 ing to directions given in Practice X. 



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