210  CONTRIBUTIONS    TO    ECONOMIC    GEOLOGY,  1905. 
GENERAL   RESULTS. 
In  addition  to  the  above  chemical  and  geologic  data  obtained  by  the  coal-testing  plai 
it  is  desirable  to  call  the  attention  of  geologists  to  a  new  and  improved  method,  develop 
during  the  course  of  this  work,  of  utilizing  coal  in  the  production  of  power.  This  meth< 
consists  of  the  conversion  of  the  coal  into  producer  gas  and  the  use  of  this  gas  in  an  explosi 
gas  engine.  A  brief  preliminary  statement  of  the  results  of  these  tests  has  been  publish 
in  Bulletin  No.  261,  and  full  and  complete  descriptions  are  contained  in  the  detailed  repc 
given  in  Professional  Paper  No.  48.  Briefly,  the  results  show  great  economy  in  the  use 
fuel  for  the  production  of  power  by  this  method.  From  the  results  so  far  obtained  it  seei 
probable  that  a  gain  in  efficiency  of  100  per  cent  may  be  expected  over  the  ordinary  practi 
with  the  steam  engine.  Although  this  gain  applies  to  all  grades  of  coal  that  were  teste 
the  most  striking  results  were  obtained  from  the  use  of  low-grade  bituminous  coals  a: 
lignites.  The  results  were  of  such  a  character  that  they  seemed  to  foretell  a  revoluti 
in  the  mode  of  generating  power  in  the  near  future,  and  if  they  are  borne  out  in  aeti 
practice  the  low  grade,  dirt}'  coals  of  Iowa  and  Missouri  may  he  made  to  yield  as  valual 
results  as  are  at  present  obtained  by  the  highest  grade  steam  coals  of  West-  Virginia.  Tl 
method  also  offers  a  great  opportunity  for  the  utilization  of  brown  lignites  of  the  nod 
wesl  and  of  Texas,  which,  up  to  the  present  time,  have  been  little  used  for  such  purposj 
Since  the  amount  of  ash  has  little  effect  in  producer  practice,  unless  clinkers  are  form* 
it  is  probable  that  this  method  will  afford  a  solution  of  the  present  great  problem  of  t 
utilization  of  slack  coals.  This  is  one  of  the  most  serious  questions  that  confront  c< 
operators  in  this  country,  and  the  experiments  so  far  conducted  at  St.  Louis  seem  to  sh< 
that  waste  products  of  this  kind  can  he  utilized  to  decided  advantage  in  a  producer  pla: 
