Am.  Jour.  Pharm.  ) 
Jan.,  1879.  f 
Tests  for  Carbolic  Acid3  etc. 
35 
of  the  tube  to  the  other.  With  a  mixture  of  two  volumes  of  Cal- 
vert's No.  5  acid  to  one  of  creasote,  the  precipitation  of  the  nitrocel- 
lulose was  very  marked. 
As  carbolic  acid,  cresylic  acid  and  creasote  boil  at  temperatures  toler- 
ably widely  apart,  I  thought  it  might  be  possible  to  effect  a  sufficient 
separation  by  fractional  distillation  to  enable  the  tests  for  the  coal  tar 
acids  to  be  more  readily  applied.  For  this  purpose  I  introduced  a  mix- 
ture of  No.  5  carbolic  acid  and  Morson's  creasote  into  a  small  retort 
and  distilled  the  liquid.  The  water  which  first  came  over  was  col- 
lected separately.  The  next  portion  of  the  distillate  (amounting  to 
about  one-fifth  of  the  whole  bulk  of  the  liquid)  was  boiled  to  free  it 
from  a  little  water,  and  was  then  tested  with  glycerin  and  with  collo- 
dion. It  dissolved  readily  in  the  glycerin,  and  precipitated  half  its  vol- 
ume of  the  collodion.  Hence  the  carbolic  acid  of  the  mixed  creasote 
was  fairly  detected,  and  there  seems  no  reason  why  fractional  distilla- 
tion should  not  serve  for  the  detection  of  smaller  proportions  of  car- 
bolic acid,  as  it  will  certainly  be  most  abundant  in  the  first  portions  of 
the  distillate.  The  ferric  chloride  test  was  not  found  of  service  for  test- 
ing the  distillate,  sufficient  creasote  being  present  to  produce  a  decided 
brown  coloration. 
As  the  tests  with  glycerin  and  collodion  are  the  only  reactions  of 
service  with  mixtures  of  carbolic  acid  and  creasote,  1  did  not  think  it 
necessary  to  apply  the  other  tests  to  the  distillate. 
It  will  be  seen  from  my  experiments  that  the  high  value  usually 
attached  to  the  glycerin  test  is  amply  justified.  It  has  been  stated 
that  pure  creasote  was  soluble  in  anhydrous  glycerin.  This  is  certainly 
not  my  experience,  but  if  it  be  true  that  some  varieties  of  creasote 
dissolve  in  absolute  glycerin  they  will  doubtless  be  precipitated  by  the 
least  dilution,  and  can  thus  be  distinguished  from  mixtures  containing 
considerable  proportions  of  the  coal-tar  acids. 
Mr.  J.  Williams  examined  a  sample  of  German  creasote  which  was 
supposed  to  be  pure,  and  which  dissolved  in  glycerin  j  but  the  fact 
that  40  per  cent,  of  the  sample  distilled  at  200  to  203,  together  with 
other  characters,  renders  it  very  probable  that  it  contained  an  unac- 
knowledged mixture  of  the  coar-tar  acids.  It  must  not  be  forgotten 
that  cresylic  acid  is  much  cheaper  than  carbolic,  and  is  far  more 
difficult  to  distinguish  from  creasote,  even  when  unmixed  with  it. 
I  have  thought  it  best  to  place  my  results  on  record  in  the  fullest 
