THE  AMERICAN 
JOURNAL  OF  PHARMACY 
MARCH,  1894.  f 
CRUDE  CARBOLIC  ACID. 
By  H.  W.  Jayne,  Ph.D. 
The  composition  and  methods  of  preparation  of  the  crude  carbolic 
acids  of  commerce  appear  to  be  so  little  understood  by  pharmacists 
generally  that  it  seems  as  if  a  few  remarks  about  them,  from  one 
who  has  practical  knowledge  of  their  manufacture,  might  be  of 
interest  to  those  present. 
Many  text-books  state  that  crude  carbolic  acid  is  prepared  by 
repeatedly  distilling  a  portion  of  the  coal  tar,  until  a  fraction  is 
obtained  boiling  between  170-1900  C,  which  is  then  extracted  with 
a  strong  solution  of  caustic  soda.  This  method  is  not  used  at 
present  in  large  works  either  here  or  abroad. 
While  it  is  possible  to  obtain  a  fraction  rich  in  acids  by  repeated 
distillation,  yet  the  total  yield  is  less,  for  a  certain  amount  is  lost  in 
each  distillation,  either  by  volatilization,  or  by  being  destroyed  by 
contact  with  the  heated  sides  of  the  still. 
In  this  country,  as  a  rule,  the  tar  is  distilled  in  two  fractions. 
The  first  consisting  of  all  the  lighter  portions  is  called  the  light  oil, 
and  is  collected  until  a  sample  of  the  oil  that  runs  from  the  still  sinks 
in  water.  The  whole  fraction  when  mixed  has  a  gravity  of  from 
0-94  to  0-99.  The  second  fraction  consisting  of  about  20  per  cent, 
of  the  tar,  constitutes  the  creosote — or  heavy  oil — commonly  called 
dead  oil.  The  residue  left  in  the  still  is  soft  pitch.  In  some  cases 
the  first  portions  of  the  dead  oil  are  collected  separately,  in  order  to 
obtain  a  fraction  as  rich  in  acids  as  possible,  which  is  then  known 
("3) 
