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The Composition of Matter 27 



other elements. At higher temperatures it combines very readily 

 with other elements, especially with oxygen. This fact we have al- 

 ready observed in the burning or oxidation of the wood splinter 

 in oxygen. 



There are three forms of carbon : diamond, graphite and char- 

 coal. These have certain characteristics in common, three of 

 which may be noted by the study of charcoal, which is nearly pure 

 carbon. 



Experiments with Carbon. Light a match. It will burn; 

 that is, the carbon in the wood will unite with the oxygen in the 

 air, and heat and light will be produced. Blow out the flame be- 

 fore the match is consumed and the black material left is char- 

 coal. By testing, it will be found tasteless and odorless. Light 

 the charcoal of the match again. Hold your hand over it. You 

 will discover that heat is given off. Charcoal, then, will burn and 

 produce heat. It is a solid and is odorless and tasteless. These 

 last three properties are characteristics of all three forms of 

 carbon. 



Nitrogen. Nitrogen is a gas found in the air, of which it 

 for.ms nearly four-fifths. It is also found in combination in a 

 large number of substances. With other elements, it forms a 

 part of animals and of plants. 



The most striking characteristic of nitrogen is its inactivity. 

 It neither burns nor supports combustion. To prove this, thrust 

 a burning match into a bottle of nitrogen and observe the result. 



Experiments with Nitrogen. 



Preparation of Nitrogen. The air is made up largely of 

 nitrogen and oxygen. To obtain nitrogen, it is necessary to re- 

 move oxygen from the air. The most convenient way is to burn 

 a small piece of phosphorus in a bell jar over water. The oxygen 

 is consumed in the burning, leaving the nitrogen. 



Another way is to place a wide-mouthed bottle over a burn- 

 ing candle that is fastened to a piece of cardboard floating on 

 lime water. When the candle ceases to burn, it shows that the 

 oxygen has been consumed. The bottle should then be turned 

 right side up, closely covered so as to retain the lime water that 

 has risen to take the place of the oxygen. By shaking the contents 



