252 



SOIL ACIDITY AND LIMING 



again with blue litmus paper. Into the other tumbler pour the teaspoonful 

 of the fine material, stir for a few seconds, and test with blue litmus paper. 

 Explain results. 



B. Repeat the test but use pure gypsum (calcium sulfate) instead of the 

 finely pulverized limestone. 



Laboratory Exercises. Material Needed. Several small strips each of 

 blue and red litmus paper; 8 tumblers; about a cupful each of 3 soils to test 

 for acidity; a half cupful each of a common salt solution, soapy water, vinegar 

 solution sweetened with sugar, and sour milk or whey; four or five saucers; 

 a piece of window glass; a small amount of pure gypsum (calcium sulfate); 

 4-quart samples of agricultural limes; a bottle Of muriatic acid; and a quart 

 of coal ashes. 



To Determine the Reaction of Different Solutions by the Use of Litmus 

 Paper. Procedure. A. Dip a small piece of blue litmus paper into an acid 

 solution provided. What happened? Try a piece of red litmus paper. Any 

 reaction? Acid turns blue litmus paper red. 



B. Dip a piece of blue litmus paper into an alkaline solution. Any reac- 

 tion? Test with a piece of red litmus paper. What change takes place? 



An alkaline solution turns red litmus paper blue. An alkaline solution 

 has an opposite reaction to that of an acid solution. 



C. Test pure water with blue and red litmus paper. 

 Water is a neutral material, neither acid nor alkaline. 



D. By the use of blue and red litmus paper determine the reaction of the 

 following solutions: 



A common salt solution; soapy water; vinegar solution sweetened with 

 sugar; and sour milk or whey. 



Question. -What is litmus? 



To Test for Soil Acidity by the Use of Blue Litmus Paper Procedure. 

 A. Place about 3 tablespoonfuls of soil in a clean saucer and moisten to a thick 

 mud with clean, soft water, previously boiled. With a clean stick separate 

 the mud into two portions and lay on one portion a piece of blue litmus paper. 

 Press the other portion of wet soil firmly down on the paper; leave for about 

 3 to 5 minutes, then carefully remove the upper portion of the soil and examine 

 the paper. Note results, and interpret. 



B. Test another soil, but this tune place the piece of blue litmus paper 

 between the two halves of a mud ball. 



C. Test a third soil. This time lay litmus paper on a piece of window 

 glass, and cover with one-half of a mud ball. 



To Show that Lime Will Correct Soil Acidity. Procedure. A. Place 

 about three tablespoonfuls of acid soil in a clean saucer and thoroughly mix 

 with it about a quarter of a teaspoonful, or less, of air-slaked lime. Moisten 

 the mixture and test with blue litmus paper as before. (Select either one of 

 the three methods.) 



B. Repeat and use pure gypsum (calcium sulfate) instead. 



Question. What effect did the lime have on the acid soil? 



To Study Different Forms of Agricultural Lime. Procedure. Examine 

 carefully the samples of different agricultural limes provided and record facts 

 and observations in tabular form as follows: 



