312 
Caffeine  from  Coffee  Soot. 
Am.  Jour.  Pharm. 
May,  1920. 
fortunately  this  cannot  be  offered,  for  the  reason  that  no  com- 
mercial roaster  equipped  with  a  soot  collector  was  met  with  in  this 
investigation.  Only  a  properly  designed  and  properly  operated 
soot  collector  will  yield  figures  for  this. 
By  coffee  soot  is  meant  the  smoke-like  vapor  which  arises  from 
the  roasting  barrel  during  the  roasting  process.  Coffee  chaff,  which 
is  also  a  by-product  of  the  roasting  of  coffee,  also  contains  caffeine, 
but  its  economic  use  for  the  production  of  caffeine  has  not  been 
rendered  possible  up  to  the  present  time.  It  contains  much  smaller 
proportions  of  caffeine  than  the  raw  materials  from  tea,  and  in  addi- 
tion contains  considerable  pyroligneous  or  tarry  matter  which 
makes  the  production  of  pure  white  caffeine  very  difficult  and  ex- 
pensive. Specimens  .of  coffee  chaff  recently  examined  in  the  Mul- 
ford  laboratories  ranged  between  0.6  and  i.i  per  cent,  in  caffein 
content, 
METHODS  01^  COIvIvECTlNG  COI^I^EE  SOOT. 
Caffeine  is  a  sublimable  substance,  that  is,  it  can  be  made  to  pass 
into  the  form  of  a  vapor  by  heat;  and  upon  cooling  this  vapor,  the 
caffeine  will  be  precipitated  as  a  crystalline  "snow."  It  is  by  the 
principle  of  sublimation  that  caffeine  is  collected ;  since  the  utilizable 
constituent  of  coffee  soot  and  flue  gases  from  the  roasting  of  coffee 
is  caffeine,  it  is  by  sublimation  that  the  caffeine  containing  coffee 
soot  is  best  collected. 
Coffee  soot  escapes  from  the  roaster  via  the  flue.  In  practice, 
a  considerable  proportion  also  escapes  into  the  room  in  which  the 
roaster  is  situated,  and  where  the  collection  of  the  soot  is  made  a 
practice  for  profit,  it  is  a  source  of  loss  of  income.  This  loss  can  be 
prevented  by  proper  regulation  of  the  draft  in  the  flue  as  described 
later  in  this  article.  Since  coffee  soot  escapes  via  the  flue,  it  is 
necessary,  therefore,  to  connect  the  collector  with  the  flue. 
Theoretically,  the  conditions  required  are  a  means  of  cooling  the 
coffee  soot  and  flue  gases  to  precipitate  the  caffeine  contained  in 
them ;  a  collector  to  retain  the  precipitated  caffeine  and  soot ;  and  a 
draught  regulator  to  control  the  rate  of  flow  of  the  soot  and  gases 
through  the  collector  so  that  it  is  not  so  fast  that  caffeine  passes 
through  the  collector  and  is  lost  in  the  outer  air,  nor  so  slow  that  the 
soot  is  lost  by  being  forced  out  into  the  air  of  the  room  in  which  the 
roaster  is  situated. 
