62 COMPANION TO TROPICAL READERS 



KINDS OF SOIL 



(See Tropical Readers, Book II, pp. 83-86.) 



Expt. 101. Sand, Clay, and Vegetable Matter in 

 Soils. Put a handful of soil in water, stir with a stick, 

 and notice that 



(a) The sand it contains settles at the bottom. 



(b) The clay remains in suspension. 



(c) The vegetable matter rises and floats. 



Expt. 102. Lime in Soils. Add muriatic acid to 

 samples of different soils, and those containing lime 

 will effervesce. 



Expt. 103. Proportion of Organic Matter in Soils. 

 Weigh 1 lb. of soil; place it on a tin sheet; heat it over 

 a strong fire for two hours, and when cool weigh it 

 again. The loss of weight is due to the organic matter 

 burnt, and to the water driven off in the form of vapour. 



Expt. 104. Leaves become Decomposed and form 

 Humus. Collect fresh leaves and leaves in various 

 states of decay, showing stages in the formation of 

 leaf mould and humus. 



Expt. 105. Humus becomes Darker in Colour when 

 Wet. Dry some leaf mould in the sun; wet it, and 

 observe that it becomes darker in colour. 



Expt. 106. Pure Sand contains no Plant Food. 

 Prepare sufficient pure sand to fill a medium-sized pot 

 by repeatedly washing ordinary sand with water until 

 no discoloration of the water used is noticed; spread the 

 clean sand out on an old shovel and heat it on a fire 

 for half an hour. When cool, plant some bean seeds 

 in the sand; observe that they grow readily at first, 

 having sufficient nourishment in the seed, but soon die, 

 owing to lack of food in the sand. 



Expt. 107. Different Kinds of Soil. By mixing the 



