CLOVERS AND OTHER LEGUMES 253 



tests of this kind and learn if there is any acid soil in the 

 fields near by. 



EXERCISE 49 



Object. — To ascertain if the soils in our fields at home 

 or in other fields near the schoolhouse are acid. 



Procedure. — Bring to the schoolhouse, wrapped in a 

 clean paper, about a pint of soil from a field at home. 

 If it is taken from one in which clover has frequently 

 failed, so much the better. This soil should not be taken 

 up or handled with the hands, but with a small paddle 

 or shovel instead. Since other members of the class 

 will also bring samples, there will be a number to be 

 tested for acidity, and they should be marked or numbered 

 to prevent their becoming confused. 



Procure, if possible, as many -clean cups, glasses or 

 cans as you have samples of soil. Put a sample into 

 each cup, fiUing it about three-fourths full. Then add 

 soft water while you stir it with a small stick until a stiff 

 mud has been formed. 



Now open a slit in this mud with a knife blade, insert 

 a slip of blue litmus paper, and close the wet soil against 

 the paper tightly with the fingers. Insert the litmus 

 slips in the other samples in the same way. Allow them 

 to remain in the wet soil for about an hour ; then remove 

 the slips, dip them in soft water to rinse off the dirt, 

 and note the color of each one. 



If any given slip is still blue, the soil is not acid; if 

 it is very faintly pink, you will know that the soil is 

 sUghtly acid ; and if it is distinctly pink, the soil is strongly 

 acid. 



Conclusion. — Write in your notebook the results of 

 the test of each sample, stating first the field from which 

 it came and then its condition as shown by the litmus 

 paper. 



