CHAPTER XXVIII 

 CARBON AND THE OXIDES OF CARBON 



THE majority of the substances composing, or produced by, 

 living organisms, such as starch, fat, and sugar, are compounds 

 of carbon. Hence the chemistry of these compounds is known as 

 organic chemistry. It was at first supposed that the artificial 

 production of such compounds, e.g., without the intervention 

 of life, was impossible. But many natural organic products have 

 now been made from simpler ones or from the elements, and the 

 preparation of the others is delayed only in consequence of difficul- 

 ties caused by their instability and complexity. On the other 

 hand, hundreds of compounds unknown to animal or vegetable 

 life, including many valuable drugs and dyes, have now been 

 added to the catalogue of chemical compounds. Hundreds of 

 thousands of different compounds containing carbon are known, 

 and thousands more are added every year. 



The elements entering into carbon compounds are chiefly hydro- 

 gen and oxygen. After these, nitrogen, phosphorus, the halogens 

 and sulphur may be named. 



CARBON C 



Occurrence. Large quantities of carbon are found in the 

 free condition in nature. The diamond is the purest natural 

 carbon. Graphite, or plumbago, which is the next purest, is 

 found in limited amounts, and is a valuable mineral. Coal occurs 

 in numerous forms containing greatly varying proportions of 

 free carbon. Small quantities of the free element have been found 

 in meteorites. 



In combination, carbon is found in marsh-gas, or methane 

 CH$, which is the chief component of natural gas. The numerous 



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