EXPERIMENTS 263 



26. Volatilizing Ammonium Salts. — In separate test-tubes place 

 about 100 milligrams each of ammonium carbonate and ammonium 

 sulphate. Apply heat gently and observe the results. Place a cold 

 glass rod in the test-tube when the white fumes are being given off. 



27. Testing for Phosphoric Acid. — Dissolve a small piece of bone 

 (5 grams) in 20 cc. nitric acid (10 cc. strong nitric acid and 10 cc. 

 water). Filter. To the filtrate add 3 cc. of ammonium molybdate, 

 warm, and shake. In a second test-tube dissolve 100 milligrams of 

 sodium phosphate in 10 cc. water and add 3 cc. ammonium mo- 

 lybdate. Compare the result with that obtained with the bone. 



28. Testing for Water-soluble and Acid-soluble Phosphates. — 

 Place 1 gram of tricalcium phosphate in a test-tube with 10 cc. 

 water. Boil. Filter through a close filter. To the filtrate add 3 cc. 

 of ammonium molybdate. Repeat the experiment, using dilute 

 nitric acid in place of water. Repeat the experiment, using mono- 

 calcium phosphate and water. 



2g. Preparation of Acid Phosphate. — Place 100 grams of pow- 

 dered tricalcium phosphate in a large lead dish. Add slowly and 

 with constant stirring 100 grams of commercial sulphuric acid, 

 using an iron spatula for the purpose. Transfer the mixture to a 

 wooden box and allow it to act for about three days. Then pul- 

 verize and examine. The material is saved for Experiment 34. 

 The mixing of the acid and phosphate should be Hone in a place 

 where there is a good draft. 



30. Testing Ashes. — Test samples of leached and of unleached 

 ashes in the way described in Section 240. 



31. Flocculation of Clay. — Ten grams of clay soil are placed in 

 a tall beaker or cylinder, 1000 cc. of water added, and the material 

 triturated. The water containing the suspended clay is divided 

 into two portions. To one portion 1 gram of calcium carbonate is 

 added and the mixture stirred. After two or three hours compare 

 the two portions. 



32. Action of Lime on Acid Soil. — In a flask place 100 grams 

 of acid peaty soil, add 5 grams of recently slaked lime and 200 cc. 

 water ; connect the flask by means of a delivery-tube with a wash- 

 bottle containing lime-water and observe the results. 



