20 CHEMISTRY, GEOLOGY 



manganese, silicia, chlorine, sulphuric acid and 

 phosphoric acid. (See Appendix, 6.) 



POTASH, as commonly found, is called a 

 salt. Its base is a metal called potassium. The 

 potash, as found in the shops, is obtained from 

 wood-ashes, by boiling them in water, straining, 

 and then boiling down to dryness. Potash is 

 thus procured by leaching wood-ashes, to which 

 any kind of fat is added, the mixture is boiled, 

 and it becomes soft-soap. Potash is an alkali ; 

 it absorbs moisture from the air, and soon turns 

 to a liquid. Its metallic base, potassium, attracts 

 oxygen from water when thrown upon it, and 

 takes fire as it floats on the surface of the water. 

 (See Appendix, 7.) 



SODA is also an alkali ; it is made from sea 

 salt. Its base is a metal called sodium. As we 

 buy it in the shops, it looks like pieces of coarse 

 glass ; these pieces are called crystals. If ex- 

 posed to the air, it soon dries and crumbles into 



Questions. What is potash ? How is potash obtained ? 

 What is its base called? Boiled with fat, what does it 

 make ? What is potash called ? How does the air act upon 

 it ? How does potassium act if thrown on water ? What is 

 soda ? What is it made from ? What is its base called ? 

 What do its crystals look like ? What does it do in the air ? 



