TYPES OF SOILS 



37 



greater amount? What per cent of water did each absorb? What 

 filled the space before the water entered ? 



9. Fill a two-quart jar about two thirds full of soil from the school 

 garden. Add water until the jar is full and let stand for a day. Then 

 shake thoroughly and let the mixture settle. How do the various mate- 

 rials arrange themselves in settling? Determine from the experiment 

 the kind of loam your soil is most like. Try the same experiment with 

 the subsoil. Is the result the same ? 



10. Put about a pint each of soil and subsoil from the school garden 

 into air-tight receptacles and bring into the laboratory. Test for mois- 

 ture and organic content as follows : Procure two small pans and weigh 

 them. Place 100 g. of soil in one and a like amount of subsoil in the 

 other, weighing quickly to avoid loss by evaporation. Expose the soil 

 to the air of the room for three days and weigh pan and soil again. 

 The difference between this and the former weight will give the amount 

 of capillary water each specimen contained. Now get two crucibles and 

 place 10 or 15 g. of the dry soil and subsoil in them. Heat in an oven 

 for five hours and weigh again. The difference in weight gives the 

 amount of the hygroscopic moisture present. Next heat each sample 

 to red heat over a Bunsen burner for half an hour and weigh again. 

 The difference now represents roughly the amount of organic material 

 in the soil. Fill out the following table : 



11. Breathe upon a glass slide, throw some sand upon it, shake off all 

 loose grains, and examine those that remain with the microscope. The 

 pink or black particles are hornblende ; the thin, clear, or dusky flakes 

 are mica ; and the gray particles are feldspar or granite. Mix up some clay 

 in water and examine a drop of the turbid fluid in the same way. How 

 do the two mounts compare as to size and composition of the particles ? 



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