PREPARATION  OF  CHLOROFORM,  ETC. 
27 
they  are  filled.  When  the  distillation  subsides,  steam  is  again 
let  into  the  still  until  the  last  traces  of  chloroform  and  of  un- 
decomposecl  alcohol  are  driven  over. 
The  crude  chloroform,  after  repeated  washing  with  water,  is 
first  re-distilled  in  a  copper  still  of  150  gallons  capacity,  which 
separates  from  it  a  large  quantity  of  black  heavy  oil,  having  an 
extremely  suffocating  odor.  The  distillate  is  then  agitated  with 
sulphuric  acid  in  a  large  leaden  revolving  box,  moved  by  steam  ; 
it  is  then  drawn  off,  and  on  standing,  until  the  acid  separates, 
the  chloroform  is  decanted  into  another  vessel  and  agitated  with 
strong  liquor  potassoe,  again  decanted  after  separating,  and  dis- 
tilled a  third  time,  rejecting  about  five  per  cent,  of  the  last 
portion  which  is  reserved  for  subsequent  purification.  The 
chloroform,  thus  obtained,  will  average  in  quantity  thirty  pounds 
of  sp.  gr.  1-495,  and  possess  a  degree  of  purity  that  fully  fits 
it  for  medicinal  use. 
The  merit  of  this  still  is  its  economy  of  labor,  as  one  operative 
can  manage  it  and  work  off  five  charges  (2500  lbs.)  of  chloride 
in  ten  hours,  which  produces  150  pounds  of  purified 
chloroform,  making  the  cost  of  labor  for  this  part  of  the  pro- 
cess less  than  a  cent  per  pound. 
Still  for  oil  of  cloves. — This  is  also  constructed  of  boiler  iron, 
cylindrical,  about  five  feet  high,  and  3|  in  diameter,  and  con- 
tains over  600  gallons.  The  dome-shaped  top  is  surmounted 
by  a  leaden  neck  connected  with  ah  ordinary  worm  condenser  ; 
and  is  provided  with  a  manhole  for  introducing  the  charge  of 
cloves,  which  is  about  350  pounds  with  300  gallons  of  water. 
A  square  lateral  opening  exists  near  the  base,  which  is  closed 
by  a  clamp  and  screw  pressing  on  an  iron  plate  with  a  gum 
joint,  the  object  of  which  is  for  conveniently  removing  the  ex- 
hausted cloves,  after  the  operation  is  concluded.  The  still  is 
heated  with  pressure  steam  in  a  coil  at  the  bottom.  The  dis- 
tillate is  received  into  a  tall  tinned  vessel,  of  three  gallons  capacity, 
furnished  with  a  funnel  at  top  projecting  down  towards  its 
centre,  and  from  near  the  top,  a  lateral  tube  issues,  bent 
upwards  and  then  downwards  so  as  to  carry  off  the  distilled 
water  which  collects  above  the  oil.  As  the  distilled  water  accumu- 
lates, it  is  returned  into  the  still  from  time  to  time.  About  a  day 
and  a  half  are  required  to  exhaust  the  charge  with  steam  of  an 
