544 
Technical  Chemistry. 
f Am.  Jour.  Pharm. 
X  November,  1900. 
and  steel,  the  most  striking  change  is  the  practical  doubling  in 
capacity  of  most  of  the  newly-designed  blast-furnaces.  The  daily 
output  of  the  coming  furnace  must  approach  600  tons  of  pig  metal,  x 
while  the  maximum  for  most  furnaces  heretofore  has  been  a  daily 
average  of  from  200-300  tons.  When  we  consider  that  only  a  decade 
ago  an  output  of  100-150  tons  daily  was  considered  good  practice, 
we  can  appreciate  the  magnitude  of  the  change  and  wonder  where 
the  limit  of  the  future  is  to  be.  The  greater  part  of  this  increase 
has  been  caused  by  doubling,  or  more  than  doubling,  blast  pres- 
sures and  blast  quantity,  thereby  increasing  the  yield  of  existing 
furnaces  and  rendering  possible  larger  hearth  diameters. 
A  considerable  increase  of  economy  in  the  use  of  fuel  for  making 
pig  iron  seems  to  have  been  accomplished  abroad  by  the  direct  use 
of  furnace  gases  in  gas  motors  for  producing  the  air  blast,  instead 
of  burning  this  gas  to  generate  steam  and  using  steam  engines  to 
operate  the  blast  pumps.  The  solution  of  this  problem  is  cause  for 
congratulation,  because  of  the  numerous  difficulties  connected  with 
it.  The  gas  from  iron  furnaces  available  for  such  motors  contains 
only  about  25  per  cent,  of  carbonic  oxide,  as  almost  its  whole  source 
of  heat  value,  besides  carrying  large  quantities  of  fine  dust  of  coke, 
ore,  etc.,  which  greatly  increases  the  difficulty  of  use  in  any 
mechanism  where  corrosion  must  be  avoided.  Any  one  who  has 
seen  the  valves  of  a  hot-blast  stove  cut  through  and  worn  out  in  a 
few  months  by  the  action  of  this  dust  will  appreciate  its  cutting 
power. 
In  Scotland,  furnaces  using  raw  coal  have  made  as  a  by-product 
about  a  tenth  of  all  the  ammonia  produced  in  Great  Britain  during 
the  year.  Certain  localities  in  the  United  States  possessing  abund- 
ant non-coking  coal  in  proximity  to  cheap  and  good  ore  might 
profitably  adopt  this  method  of  iron  manufacture,  notably  the  new 
Michigan  coal  district  of  the  Saginaw  Valley,  which,  by  this  means, 
could  easily  supply  the  whole  of  the  iron  used  in  Michigan  districts 
and  all  of  the  ammonia  needed  in  the  newly  developing  alkali 
industries  of  that  locality. 
Another  important  factor  in  the  great  increase  of  furnace  capacity 
for  the  production  of  pig  iron  has  been  the  installation  of  automatic 
labor-saving  devices  for  handling  furnace  charges  and  removing 
furnace  products.  The  most  important  of  these  are  the  car  and 
ore-loading  machines  of  Brown,  McMyler,  Lindsey  and  Hulett,  the 
