4. Place some lime which has not been slacked (calcium oxide) in some water in a test 

 tube, (a) Is it at all soluble? (b) Does it have acid, neutral, or alkaline properties? (c) 

 How may acid soils be made neutral or slightly alkaline? Reference: "Soils and Fertility," 

 Whitson & Walster, page 90. 



Part C. Phosphorus. 



5. (Classroom experiment.) Since the element phosphorus has a great affinity for oxy- 

 gen and other elements it is never found free in nature. In combination with other elements 

 it is quite abundant and widely distributed. All fei tile soils contain phosphorus. 



In order to keep the element phosphorus from uniting with the oxygen of the air it must 

 be kept beneath water. Caution: Remember that phosphorus when not under water may 

 burst into flame at any moment. It should never be allowed to come in contact with the 

 hands or other parts of the body. 



Place a small piece of phosphorus in a dry evaporating dish. Tench it with a glass rod 

 which has been slightly heated. Cover the dish with a 500 cc beaker, (a) Describe the action 

 which takes place, (b) Describe the product left in the beaker, (c) The product left in the 

 beaker is the result of the union of what two elements? 



6. Primary calcium phosphate is one cf the important commercial fertilizer compounds 

 containing phosphorus. Examine a sample of the compound, (a) Describe its appearance, 

 (b) Test its solubility, (c) Is its action acid, neutral, or alkaline? 



Part D. Nitrogen. 



7. (a) What per cent of the air consists of the element nitrogen? (b) Does it appear 

 that there is an abundant supply of nitrogen in the air above the soil and also in the soil? (c) 

 What evidence can you give to show that the element nitrogen is not as active as potassium, 

 phosphorus, or calcium, (d) Since the element nitrogen is not as active as most other ele- 

 ments, what may you infer as to the relative abundance of its compounds? (e) What might 

 you infer concerning the cost of nitrogen compounds as compared with the cost of potas- 

 sium, phosphorous, or calcium compounds when purchased as artificial fertilizers? 



8. Sodium nitrate is a nitrogen compound common in commercial fertilizers. Examine 

 a sample of sodium nitrate, (a) Describe its appearance, (b) Test its solubility, (c) Is it 

 acid, neutral, or alkaline in its action? 



