636  Methyl  Alcohol  and  Ethyl  Alcohol     { ^?eptember^V92a 
average  of  80  per  cent,  and  is  ready  to  be  placed  in  bags  for  ship- 
ment. 
Drying  Floors. — The  drying  floors  are  over  the  tops  of  the  ovens, 
and  are  made  of  tile  brick  or  concrete.  They  are  supported  by 
I-beams  or  rails  and  are  so  designed  that  they  utilize  the  waste  heat 
above  the  tops  of  the  ovens. 
Weak  Alcohol. — Returning  to  the  lime  lee  still,  the  vapor  which 
passes  off  when  the  contents  are  heated  goes  through  a  tubular 
condenser  and  the  condensation  product,  termed  weak  alcohol, 
is  conveyed  into  steel  tanks,  the  capacity  of  which  is  sufficient  to 
supply  one  charge  for  the  alcohol  still. 
Alcohol  Still. — The  weak  alcohol  is  piped  from  the  tanks  just 
mentioned  to  a  steel  alcohol  still,  equipped  with  a  copper  steam 
heating  coil  and  with  a  copper  fractionating  column.  Its  purpose 
is  to  remove  the  water  from  the  solution  and  to  produce  82  per 
cent,  wood  alcohol  (called  crude  alcohol),  which  is  the  grade  manu- 
factured in  most  of  the  wood  distillation  plants. 
Woods  and  Yields. — The  principal  kinds  of  hard  woods  used  in 
destructive  distillation  are  beech,  birch,  maple,  oak,  hickory,-  red 
gum  and  others  which  are  comparatively  free  from  gums,  tannins, 
etc.  Any  part  of  a  tree  can  be  used  down  to  the  branches  two 
inches  in  dimater.  The  wood  is  allowed  to  season  for  several  months 
before  being  carbonized,  the  idea  being  to  allow  nature  to  remove 
as  much  as  possible  of  the  superfluous  water  in  the  wood.  Differ- 
ent kinds  of  woods  yield  different  quantities  of  by-products,  the 
average,  it  is  said,  being  about  as  follows  for  each  cord  of  wood: 
Charcoal,  50  to  60  bushels;  acetate  of  lime,  190  to  240  pounds; 
82  per  cent,  wood  alcohol,  9  to  12  gallons.  Charcoal  weighs  ap- 
proximately 20  pounds  to  the  bushel. 
The  crude  wood  alcohol  is  taken  from  the  alcohol  still  of  the 
crude  wood  plants,  and  shipped  to  wood  alcohol  refineries,  the  prin- 
cipal ones  in  the  United  States  being  located  in  Buffalo,  N.  Y., 
and  Newark,  N.  J.  Here  the  crude  alcohol  is  first  pumped  into 
storage  tanks,  and  after  careful  analysis,  showing  the  amount  of 
alcohol,  amount  of  acetone,  and  amount  of  oils  present,  it  is  drawn 
into  big  iron  stills,  where  it  is  treated  with  an  amount  of  caustic 
soda,  sufficient  to  take  care  of  oils  and  impurities  indicated  by  the 
analysis. 
After  this  reaction  has  had  an  opportunity  to  proceed  to  the 
right  point,  it  is  distilled,  the  distillate  being  water-white  and  gath- 
