APPENDIX. 89 



the phosphorus, forming phosphoric acid, and the nitro- 

 gen alone remains. After the combustion of the phos- 

 phorus, the water will have risen in the bottle so as to 

 fill it one-fifth, the quantity of oxygen the air contained ; 

 the remaining four-fifths are nitrogen. 



6. Let the teacher submit to the class specimens of 

 common pear lash, of washing-soda, of quick-lime, of cal- 

 cined magnesia, oxide (rust) of iron, silicia, as flint or 

 quartz, chlorine gas, a bottle containing sulphuric acid, 

 phosphoric acid in the form of burnt bones, etc. By 

 this mode of ocular demonstration his class will soon 

 become acquainted with the names and appearances of 

 these several articles. 



% 



7. Let the class taste a dilute solution of potash, that 

 they may recognize the alkaline taste. 



8. Exhibit a crystal of common washing-soda, and let 

 the class taste it. 



9. Let the class look at and cautiously taste a piece 

 of quick-lime. Pour upon it a little water, that it may 

 fall to pieces. Explain the word slake, as applied to 

 this process. 



10. Describe metals as bodies having more or less 

 lustre, weight and malleability. Hammer a piece of 

 lead and a piece of stone, and explain the difference in 

 the result. 



8* 



