periment, using clay instead of silt. (b) Observe any effect of sand upon the tenacity of 

 clay, (c) Infer what relation exists between the size of particles and the tenacity of soils 

 when wet. 



9. (a) Dip a stone into water in a basin and then remove it. Observe the surface of 

 the stone, (b) Pour a little water on the stone while you hold it over the basin. Observe 

 whether or not much more water can be made to cling to the stone, (c) Break the stone 

 in two. Compare the total surface area of the stone before and after breaking, (d) Dip 

 the broken parts into water. Compare the amount of water held on the surface of the 

 stone before and after breaking, (e) Imagine this breaking of the stone to be continued. 

 What relation do you observe to exist between surface area and water-holding capacity? 



10. Fill an evaporating dish }£ full of sand. In another evaporating dish, place an equal 

 amount of silt. In another, clay. Now, fill three test tubes with equal volumes of water. 

 Number the tubes 1, 2 and 3. Use the water from tube No. 1 to moisten the sand suf- 

 ficiently to allow it to pack, but not enough to allow drainage from the dish. In like man- 

 ner, moisten the silt with water from tube No. 2. Moisten the clay with water from tube 

 No. 3. In each case, the soil should be thoroughly moist, but not sufficient to allow drain- 

 age from the evaporating dishes, (a) Observe which soil requires the most water to moisten 

 it. (b) Infer the cause of any difference in the amounts required. 



11. Dip a glass tube into water. (a) Observe the height of water within the tube as 

 compared with the water level outside. Dip the end of a strip of blotting paper or a piece 

 of crayon into the water, (b) Does the action appear to be related to that just observed? 

 Such phenomenon is called capillarity. 



12. On the supply table you will find three Argar.d chimneys, standing in a basin of 

 water. Chimney No. 1 is filled with sand; No. 2 with silt; No. 3 with clay, (a) *Observe 

 the rate at which the water rises in the different soils, (b) What name is applied to such 

 phenomena. 



13. At the next laboratory period, the apparatus used in Exp. 12 will be fitted in such 

 a way that water can be drained through the soils under similar conditions. Leave six or 

 eight lines on your note paper that you may fill in the answers to the following observations 

 and inferences which you will make at the next laboratory period, (a) Observe any dif- 

 ference in the rate at which water drains through the soils, (b) Infer any reason for the 

 differences observed. 



14. From your study of preceding experiments answer as best you can the following 

 questions. State brief reasons for each answer. 



(a) Soil of what texture will allow the least surface runoff? 



(b) Which soil will best stand stirring immediately after a rain? 



(c) Which one requires the greatest draught to stir, i. e., in the language of the farmer, 

 which is the "heaviest" soil? 



(d) A cubic foot of which soil will hold the least water? 



(e) Soil of what texture will loose through surface evaporation the least per cent of 

 water from deeply penetrating rains? 



15. Place a little olive oil on the back of the hand, (a) Observe the feeling — cool or 

 warm, (b) Repeat, using water, then alcohol. Observe which of the three liquids evaporates 

 most rapidly, (c) Do you observe any relation to exist between the sensation produced 



• Note. The results of this experiment are true only for a short distance above the level of the water 

 in the basin. It will be found interesting to repeat this experiment using glass tubes three or four feet in 

 length. 



15 



