However,  such  admission  must  be  most  carefully  arranged,  as  an  excess  tends  to
mnke  the  producer  extrpmely  hot  (through  complete  combustion),  and  also  a  large
formation  of  CO2  (with  attendant  waste).  If  a  httle  air  is  admitted  the  producer
fills  up  with  soot  and  packs  as  aforesaid.  The  mean  between  these  two  extremes
should  be  observed.
It  is  possible  to  use  almost  any  fuel  possessing,  say  20%  of  combustible  matter,
in  a  producer  of  this  type.  The  writer  in  a  100-h.p.  producer  of  similar  construction
has  obtained  a  brake  h.p.  for  about  two  and  one-half  pounds  of  straw  and  about  the
same  amount  of  hay  gasified.
In  practice  he  has  found  it  advantageous  to  chop  the  hay  and  straw  coarsely
in  one  of  the  ordinary  chopping  machines  used  for  this  purpose.  After  feeding  it
into  the  producer  it  may  be  rammed  down  with  a  square-headed  tamp.
In  sugar  plantations  bagasse  is  equally  available  and  makes  an  excellent
fuel.
Smoke. — Where  bituminous  fuel  is  used  in  producers  under  the  observation  of
"smoke-nuisance  laws"  or  health  department  regulations,  smoke  may  be  obviated
during  the  run  by:  (a)  properly  regulated  combustion  (sufficient  mix  of  secondary
air);  (h)  light  and  frequent  firing;  (c)  the  maintenance  of  a  fairly  high  heat  in  the
combustion  zone;    (rf)  not  too  deep  a  distillation  zone.
