LIFE, CARBON'S OUTSTANDING PROPERTY 63 



molecule of naphthalene, a solid substance that forms fine 

 glittering crystals. Substances containing three or more 

 compounded rings are also known. 



The six-membered rings are not the only ones known; 

 there are also three, four, and five-membered rings. More- 

 over ring systems may have attached to them one or more 

 open carbon chains of the kind first described. Any type 

 and length of chain may be attached to any ring system. 



Obviously the number of variations is enormous. It is 

 impossible to enumerate here all known carbon-hydrogen 

 compounds, since several thousands are known. If other 

 elements such as oxygen or nitrogen enter these structures 

 the number of known compounds increases to an amazing 

 degree. The discovery of all these substances was ac- 

 complished within a century, since the first organic com- 

 pound, urea, was made by Wohler in 1828. Beilstein's 

 famous handbook of organic chemistry which registers all 

 known compounds has grown from two thin volumes to 

 twenty-three thick ones, within the last century. 



In his search for new carbon compounds the chemist is 

 guided by structural formulas such as those depicted above. 

 With confidence he draws pictures of the atom-built struc- 

 tures. In these structural formulas he picks out weak 

 spots as well as strong spots. In this way he anticipates 

 where a carbonic structure can be broken up into simpler 

 groups, or how molecules can be fitted together. 



Never has any theory been so fruitful of results. Back 

 in his laboratory the chemist finds the fragments of which 

 living nature is composed. He puts them together to pro- 

 duce artificially the complicated products of nature. Clever 

 ways must be devised to make the parts unite and to unite 

 them right. Nature's own ways of making these substances 

 are shrouded with deep mystery. The chemist has to find 

 his own ways which are widely different from the natural 

 ones and quite artificial. 



