1 ( J2 WALL'S MANUAL 



all those called geological formations, and which form 

 the crust of the earth. 



The chemical constitution of rocks, the nature, 

 properties and relations of their elements, prove to be 

 of the highest importance to the farmer, when it is 

 known that the elements of these seven minerals are 

 also the earthy part or ashes of all plants. 



The number of elements which chemistry has 

 detected, is sixty-two. These are classed as metallic 

 or unmetallic. Of these, some are gaseous, others 

 earthy, most of them combustible, 



ELEMENTARY BODIES. 



Of the simple elementary bodies, thirteen chiefly 

 compose rocks and the mineral proportion of the soil. 

 Six of this number are unmetallic, and seven are 

 metallic substances, viz, : 



The unmetallic are: 



1. Oxygen, 



2. Hydrogen, 



3. Silicon, 



4. Carbon, 



5. Sulphur, 



G. Phosphorus. 



The metallic are : 



1. Potassium, 



2. Sodium, 



3. Calcium, 



4. Magnesium, 



5. Aluminium, 



G. Ferrum or Iron, 



7. Manganese. 



Chemistry tells us how these gaseous and metallic 

 substances combine, and the elements they form after 

 combination. Oxygen has a wide range of affinities. 

 It combines with the unmetallic substances its com- 

 pounds are called oxides thus : 



Oxygen combined with Hydrogen forms Water. 



" Silicon " Silicic Acid. 



" Carbon " Carbonic Acid. 



" Sulphur " Sulphuric Acid. 

 " Phosphorus " Phophoric Acid. 



Again, with metallic substances : 



Oxygen combined with Potassium forms Potash. 

 " Sodium - " Soda. 

 u Calcium " Lime. 



" Magnesium " Magnesia, etc. 



