AFJb™a?y,Pih9Sm'i      Fat  Decomposition  and  Glycerin.  73 
glycerin  possible  is  obtained  consistent  with  good  color.  Neither 
the  first  nor  second  class  of  goods  goes  to  the  distillation  plant. 
Third.  Very  41  off  "  cotton  oil,  house  grease,  olive  oil  foots,  and 
cotton-seed  foots  go  to  the  distillation  plant  and  are  "  robbed  "  of 
all  the  glycerin,  as  color,  in  the  Twitchell  plant,  is  of  no  importance 
— the  distilled  product  will  be  white  any  way. 
Outside  of  the  distillation  plant  the  work  is  carried  on  exclusively 
in  wooden  vats  or  tanks,  each  tank  numbered  for  convenience  and 
record,  and  are  designated  as  decomposing,  acid  boil,  Twitchell,  and 
storage.  The  decomposing  and  acid  boil  tanks  are  preferably  lead 
lined.  The  Twitchell  tanks  are  closely  covered  with  snug  fitting 
lids  with  an  "  up  take  "  for  steam.  Experience  has  taught  that  cer- 
tain precautions  must  be  taken  to  carry  out  the  process  successfully 
and  economically  and  these  will  be  referred  to  at  the  proper  time. 
Assuming  that  a  plant  has  just  been  installed,  it  is  of  prime 
importance  to  understand  that  in  a  glycerin  refinery  and  a  Twitchell 
distillation  plant  twenty-four  hours  make  one  day  and  seven  days 
make  a  week  and  there  are  fifty-two  weeks  in  one  year,  and  there 
are  no  Sundays,  holidays,  or  even  lunch  hours,  one  shift  of  em- 
ployees relieving  the  other  without  any  interruption  of  work.  The 
plant  is  ready,  a  tank  car  of  cotton-seed  foots  has  been  set  about 
5.30  p.m.,  each  tank  car  is  fitted  with  a  closed  steam  coil  with  outside 
connections,  the  coil  is  connected  with  a  steam  supply  in  the  "  pump 
house  "  before  which  the  tank  has  been  placed,  and  steam  turned  on 
to  heat  and  soften  the  "  foots "  for  pumping  in  the  morning. 
One  of  the  precautions  for  successfully  working  the  process  is  that 
the  fat  must  be  freed  from  all  dirt,  lime,  bone,  tissue,  and  other 
impurities,  which  sounds  complicated  but  is  very  simply  done. 
The  dirt  settles  '  and  is  run  off  to  the  sewer.  The  contents  of 
the  car  being  softened  the  pump  is  started.  A  "  pet  cock  "  on  the 
pressure  side  of  the  cylinder  enables  the  operator  to  obtain  a 
"  running  sample  "  of  the  contents  of  the  car.  This  amounts  to 
about  three  gallons.  This  sample  is  taken  to  the  laboratory,  thor- 
oughly mixed  and  divided  into  four  parts,  three  parts  sealed  in  pint 
jars  until  the  car  of  stock  is  run  through  and  the  fourth  part  for 
"  immediate  analysis  "  of  total  fatty  acid.  Five  to  10  grammes  are 
weighed  into  a  500  c.c.  Erlenmeyer  and  50  c.c.  of  a  5  per  cent, 
alcoholic  soda  solution  added.  Boil  to  dryness.  Add  an  excess  of 
dilute  sulphuric  acid  and  boil  until  all  soap  is  decomposed.  Transfer 
to  a  separatory  funnel  using  some  petroleum  ether  to  rinse  Erlen- 
meyer.  Draw  water  and  acid  off  the  Erlenmeyer.   Pour  the  solution 
