APPENDIX. 91 



guished. Pour it from a bottle upon a lighted taper 

 (Figs. 10 and 11), proving its density to bo greater than 

 the atmosphere. Put a little bit of phosphorus into a 

 bottle of chlorine ; the phosphorus will be ignited, and 

 BO will filings of zinc, if allowed slowly to fall into a bot- 

 tle of this gas. Show its bleaching powers by its action 

 on an infusion of red cabbage, and other vegetable 

 colors. 



13. Put a piece of straw into a little sulphuric acid, 

 and show its decomposing power, as it charrs or changes 

 the straw into carbon. Explain that, although sul- 

 phuric acid exists in plaster of Paris, alum, Glauber 

 salts and Epsom salts, all of which should be exhibited 

 to the class, they are not possessed of its burning or 

 corrosive properties. Add water, very cautiously, to a 

 portion of the acid placed in a tea-cup, and show the 

 great heat produced by their combination. When very 

 largely diluted, let the solution be tasted, that acidity 

 may be recognized in contradistinction to the taste of 

 alkalies. Add a little sulphuric acid to an infusion of 

 red cabbage, showing that acids redden vegetable sub- 

 stances ; then to the reddened solution add any alkali, 

 until the acid is neutralized, and the alkali is slightly 

 in excess, and show the production of the blue color. 



Next, add an alkali to the infusion of red cabbage, 

 and show the change effected by alkalies. Then neu- 

 tralize the alkali by the addition of sulphuric acid, and 

 as soon as the acid is slightly in excess the bright red 

 coW will be again produced. 



