APPENDIX. 9 



is instantly extinguished. Now, while the wick contin- 

 ues red, plunge the candle into a bottle of oxygen, and 

 it will be again enkindled into a flame. 



16. Introduce a piece of kindled charcoal into a bot- 

 tle of oxygen gas. When the charcoal no longer burns, 

 which it will, for a short time, with great brilliancy, 

 put a lighted taper into the bottle, and the presence of 

 carbonic acid gas will be recognized by its being instantly 

 extinguished. 



17. To form humic acid, the teacher will dissolve a 

 little common soda in water, boil the solution upon 

 finely-powdered peat, or rich dark soil. Pour off the 

 solution when it has become clear. The soda has united 

 with the humic acid. Now add a little diluted muriatic 

 acid ; the muriatic acid will combine with the soda, 

 forming muriate of soda, which remains hi the solution, 

 and the humic acid, being liberated, falls down in brown 

 flakes. This humic acid consists of carbon and water 

 only, or of carbon, hydrogen and oxygen. 



18. Mix a little flour with water into a dough ; put 

 it into a large tumbler full of water, over the top of 

 which is tied a piece of fine muslin. Shake it a while, 

 then pour off the water, carrying with it the starch ; 

 add fresh water until it comes away quite clear. Let 

 the water containing the starch stand a while, so that 

 the starch may settle to the bottom and be collected. 

 Then exhibit the gluten remaining after all the starch 

 has been thus washed away. 



