332 APPENDIX 



with distilled water. Perforate the filter with a sharpened match- 

 stick, rinse its contents into a test-tube with the aid of a wash 

 bottle. Allow the solid to settle and pour off as much as possible 

 of the water. Add 5 cc. of hydrochloric acid. Warm until the 

 precipitate has dissolved. Boil for 4 or 5 minutes. Nearly neutral- 

 ize with ammonium hydroxide and add ammonium carbonate. 



The concentrated filtrate is poured from the evaporating dish into 

 a test-tube, diluted, rendered alkaline with ammonia and treated 

 with hydrogen sulphide. 



EXP. 40. To a solution of magnesium sulphate add ammonium 

 hydroxide solution. 



EXP. 41. To 5 cc. of magnesium sulphate solution add 5 cc. 

 of ammonium chloride solution, then add ammonium hydroxide 

 solution. 



EXP. 42. To the solution obtained in the last experiment, add 

 hydrogen sodium phosphate solution. 



ALUMINUM 



EXP. 43. Dilute a little aluminum sulphate solution and add 

 an excess of ammonium hydroxide solution. 



EXP. 44. Prepare, in separate test-tubes, very dilute solutions 

 of potassium hydroxide and of sulphuric acid, and study their ac- 

 tion upon aluminum sulphate, as follows : 



Dilute 10 cc. of the aluminum sulphate solution with an equal 

 bulk of water and add potassium hydroxide, drop by drop, until a 

 precipitate, which forms at first, disappears upon shaking the test- 

 tube. Divide the solution into equal halves (a) and (b). Acidify 

 portion (a) with dilute sulphuric acid, drop by drop, until the pre- 

 cipitate, which forms at first, again disappears. Reunite portions 

 (a) and (b) . Write five equations expressing the various reactions 

 that have taken place. 



EXP. 45. Mix, upon a watch-glass, concentrated aluminum sul- 

 phate solution with concentrated potassium sulphate solution. 



EXP. 46. Throw a little aluminum foil into a test-tube con- 

 taining some strong hydrochloric acid. 



