14.  Carbon  is  a  prominent  part  of  the  solid  substance  of
animals  and  plants.  After  the  gases  were  given  off  in  the
preceding  experiments  a  black  substance  was  left  in  the
pipe.  The  same  thing  occurs  when  we  burn  an  ordinary
match;  that  is,  certain  gases  burn  and  produce  the  flame
and  a  charred  mass  is  left.  This  black  material  we  know  as
charcoal;  at  the  gas-factory  a  similar  substance  from  heated
coal  is  called  coke.  The  black  color  of  coke  and  charcoal
is  due  to  the  presence  of  an  element  known  to  chemists  as
carbon.  The  easiest  way  to  get  pure  carbon  is  by  charring
white  sugar  with  intense  heat.  Chemists  know  more  than
one  hundred  thousand  compounds  of  carbon  with  other
elements.  It  is  especially  abundant  in  the  organic  com-
pounds of  which  the  bodies  of  animals  and  plants  are  com-
posed, and  consequently  must  be  also  in  the  food  from
which  the  body  substances  are  made.
