330 APPENDIX 



adhere. Hold the specimen tube in a wire support, and heat the 

 solid mixture gently; ammonia will be given off, as can be recognized 

 by the litmus paper. When the test-tube appears to be well filled 

 with the gas, remove it from the generating apparatus and hold its 

 open end under the surface of some water contained in a beaker. 



EXP. 27. Place a few cubic centimeters of ammonium chloride 

 solution in an evaporating dish, add 4 to 5 drops of potassium hy- 

 droxide. Test the mixture with litmus paper. Now warm, holding 

 pieces of moistened red litmus paper above the surface of the liquid 

 until no more alkaline gas is given off. Test the solution with red 

 litmus paper. 



EXP. 28. Place a little dry ammonium chloride in the bottom of 

 a dry test-tube and warm until the salt has volatilized. It will be 

 observed to condense into crystals upon the cold walls of the test- 

 tube. This is called "sublimation." 



CALCIUM GROUP 



EXP. 29. Weigh a clean porcelain crucible; add about one gram 

 of calcium carbonate, weigh again. Heat on pipe-stem triangle 

 gradually, using chimney on burner, for about fifteen minutes. Cool, 

 weigh. The loss represents carbon dioxide. Pour some water on the 

 residue, and note behavior. Test with litmus paper. 



EXP. 30. Hah* fill a test-tube with calcium hydroxide solution. 

 Pass in carbon dioxide by means of a clean glass tube until the 

 precipitate which has first formed re-dissolves. Write two equations 

 to express what has taken place. The solution that you obtained is 

 to be divided into three parts and used in the three succeeding 

 experiments. 



EXP. 31. To one-third of the above solution add calcium hy- 

 droxide solution. 



EXP. 32. Dilute"another portion to ten times its volume with 

 distilled water, in a flask. Add twenty drops of soap solution and 

 shake vigorously. 



EXP. 33. The last portion is to be boiled, filtered into a per- 

 fectly clean flask, diluted to ten times its volume with distilled 

 water. Add twenty drops of soap solution, and shake vigorously. 



