248  Purified  Cresol  {Cresylic  Acid).       i^""' %r-I.\^9^: 
PURIFIED  CRESOL  (CRESYLIC  ACID).* 
By  Herbert  C.  Hamii^ton, 
research  laboratory,  parke,  davis  &  company,  detroit,  mich. 
One  of  the  minor  problems  arising  from  the  war  because  of 
interference  with  importations  from  Europe  was  that  of  obtaining 
a  substitute  or  equivalent  for  trikresol,  a  proprietary  article  imported 
from  Germany  and  extensively  used  as  a  preservative  and  disin- 
fectant. As  has  been  shown  to  be  true  in  many  other  instances, 
it  is  equally  true  in  this  case  that  there  is  no  lack  in  America  either 
of  crude  material  or  of  ability  to  purify  it.  There  was  required  only 
the  incentive. 
Trikresol  is  so  named  because  it  is  a  mixture  of  the  three  isomeric 
cresols  naturally  occurring  in  coal  tar.  These  three  cresols  are  iden- 
tical in  composition,  but  have  different  physical  and  bactericidal 
properties.  These  differences,  however,  are  unimportant  and  noth- 
ing of  practical  value  results  from  their  separation. 
Trikresol,  while  useful  as  a  general  antiseptic  and  germicide, 
with  a  phenol  coefficient  of  2V2  to  3,  found  its  more  extensive  appli- 
cation as  a  preservative  for  serums,  vaccines  and  similar  biologic 
substances.  Careful  research  has  proved  that  for  this  purpose,  with 
one  exception,^  no  other  antiseptic  has  been  found  entirely  suitable, 
either  because  of  its  efficiency  or  the  toxic  or  irritating  action  when 
absorbed  from  a  hypodermic  injection. 
The  cresols  have  practically  the  same  toxicity  as  pure  phenol, 
as  shown  in  the  accompanying  table,  but  the  corrosive  action  is  so 
low  and  the  germicidal  value  so  high  in  comparison,  that  the  use 
of  phenol  as  a  germicide  is  no  longer  logical.  To  illustrate:  cresol 
with  a  coefficient  of  3,  when  diluted  i  to  60,  is  equal  in  every  respect 
to  a  5  per  cent,  solution  of  phenol,  while  the  toxicity  of  the  solu- 
tion is  only  one-third  as  great  because  of  the  degree  of  dilution,  and 
the  corrosive  action,  while  not  measurable  with  accuracy,  is  less  than 
one-third  as  great. 
Superficially  trikresol  is  identical  with  the  cresols  of  coal  tar, 
since  an  average  sample  of  the  latter  contains  not  over  5  per  cent, 
of  constituents  other  than  the  cresols.  But  it  was  very  promptly 
observed  that  cresol,  as  it  appears  on  the  market  under  various. 
*  /.  Ind.  Eng.  Chem.,  Jan.  9,  1920. 
^  Carl  Voegtlin,  Hygienic  Laboratory,  Bulletin  96. 
