LABORATORY EXERCISES 251 



Whenever liming alone increases general crop production, 

 fertilizer needs become more urgent, since the increases make a 

 heavier draft on the soil reserve of the plant-food elements. 



Though there are many crops that can tolerate acidity, yet 

 most of them will respond to liming because of the favorable con- 

 ditions created within the soil by the added lime. It is, indeed, a 

 deplorable fact, that in some sections farming without the use of 

 agricultural lime represents much waste of time, money and effort. 



Illustration Material for Lessons. — Show 3 forms of agricultural lime — 

 burnt lime, hydrated lime and air-slaked lime (carbonate of lime). 



Show 2 or 3 other lime carbonates. 



Show a good grade of pulverized limestone, or other forms of agricul- 

 tural* Hme. 



Demonstrations. — Material Needed. — Several strips of blue htmus paper; 

 a little vinegar; an orange; an apple; a httle ammonia water; a pint each of 

 strongly acid upland soil and undramed acid peat; a Truog soil-acidity testing 

 outfit; a small baking-powder can; a bottle of muriatic acid; several materials 

 containing lime carbonate; 12 tumblers; a 20-mesh screen; a 100-mesh screen; 

 2 tablespoonfuls of coarsely crushed limestone; and a teaspoonful of very finely 

 pulverized limestone. 



To Demonstrate the Reaction of Acid Substaxices, Including an Acid 

 Soil, on Blue Litmus Paper. — Procedure. — ^With blue htmus paper test the 

 reaction of vmegar, of water, ammoma water, apple juice, orange jmce, and 

 of strongly acid soil. 



Question. — ^When is a soil said to be acid or som-'i* 



To Demonstrate the Truog Acidity Test. — Procedure. — ^FoUow directions 

 aceompanymg testing outfit. 



A. Demonstrate the reaction of a strongly acid soil. 



B. Test the same soil, only use hard water instead of distilled water. Ex- 

 plain results. 



To Demonstrate the Nature of Soil Acidity. — Procedure. — A. Fill a small 

 baking-powder can with an acid sandy soil. (Perforate the bottom and place 

 a piece of cheese cloth over the bottom.) Allow about 4 quarts of hot soft 

 water to percolate through the sand. Dry a sample and retest for acidity. 

 Compare the results with first test. 



Question. — ^Why is it not possible to wash out the "acidity" in the 

 sandy soU? 



B. Kepeat the experiment and use an undrained acid peat soil. Ex- 

 plain results. 



To Show How to Test for a Carbonate. — Procedure. — ^Put a teaspoonful of 

 lump lime into a tmnbler and pour on it about a tablespoonful of dilute muri- 

 atic acid. Repeat test and use air-slaked lune, limestone, shells, coral, etc. 



To Demonstrate that the Fine Material in Pulverized Limestone is the 

 Quick-actuig Material. — Procedure, — A. Ob tarn about 2 teaspoonfuls of 

 crushed limestone (from a sample of pulverized limestone) that will not pass 

 through a 20-mesh screen. Wash this coarse material thoroughly several 

 times with acidulated water to remove all adhering fine particles. Obtain a 

 teaspoonful of fine material that will pass through a 100- or 200-mesh screen. 

 Fin a tmnbler half full of water and add a few drops of muriatic acid to make 

 distmctly acid to blue htmus paper. Mix thoroughly. Pour one-half of the 

 acid solution into a second tumbler. Into one put the two teaspoonfuls of 

 coarse particles of limestone, stir, and let stand 30 or 45 miautes, then test 



