6 CARBON. 



Their names are Carbon, Oxygen, Nitrogen and 

 Hydrogen. 



The whole of the organic part of vegetables and 

 plants, the whole of the atmosphere, all water, and a 

 very large part of the solid rocks which make up this 

 globe, consist of one, two, three, or all of these four 

 substances united in different proportions. These 

 names then stand for bodies of immense importance; 

 and it is very necessary that every farmer should at 

 least know something about them. The three last, 

 oxygen, hydrogen and nitrogen, we find in their pure 

 state as gases : gas is the chemical term for the dif- 

 erent kinds of air. The other substance, carbon, is 

 found in nature as a solid, and to this we will first 

 direct our attention. 



Carbon is a solid, usually of a black color, and 

 having no taste or smell. All the varieties of carbon 

 burn more or less freely in the air, and, while burning, 

 are converted into a gas called carbonic acid gas: this 

 will by-and-by be described. 



One very abundant form of carbon is common 

 charcoal; another is lampblack; others are coke and 

 blacklead: the most beautiful form is the diamond. 

 This, strange to say, though it looks so pure, clear and 

 beautiful, and bears so high a price, does not diffier at 

 all in its composition from common charcoal! A 

 diamond can easily be burned by a high heat, and the 

 product of the burning will be carbonic acid gas, just 

 as when charcoal is burned. Charcoal seems to be 

 soft; but if the fine powder in small quantity be rub- 

 bed between plates of glass, it is found that the little 

 particles are very hard, and able to scratch the glass 

 almost as easily as the diamond itself. 



Charcoal has strong disinfecting properties : liquids 

 that are quite offensive in smell, when filtered through 

 it, become pure and sweet. The color is also extracted 

 from many liquids by it. Some of these effects are 



