Am'Nov.1!'l88h7frm•}      Commercial  Carbolic  Compounds.  581 
SIMPLE  SUGGESTIONS  FOR  THE  PURCHASE  AND 
ASSAY  OF  COMMERCIAL  CARBOLIC  COMPOUNDS 
USED  FOR  SANITARY  PURPOSES.1 
By  John  Muter,  F.R.S.E.,  F.I.C.,  and  L.  De  Koningh,  F.I.C. 
Owing  to  the  extensive  use  of  these  compounds  by  the  various  local 
sanitary  authorities  throughout  the  country,  and  the  occasional  de- 
mands on  the  official  analyst  for  their  valuation,  it  is  very  desirable, 
both  in  the  interests  of  the  producers  and  the  consumers,  that  there 
should  be  some  simple  and  definite  methods  agreed  upon  for  their  an- 
alysis.   Up  till  the  present  time  we  venture  to  think  that  if  the  same 
sample  were  sent  to  any  dozen  analysts,  taken  by  chance  all  over  Great 
Britain,  not  more  than  two  or  three  would  come  within  measurable 
distance  of  each  other  in  the  percentage  of  carbolic  acid  found,  while 
it  is  more  than  probable  that  the  manufacturer's  chemist  would  dis- 
agree with  all.    This  state  of  things  is  caused  : 
(1)  By  the  fact  that,  very  probably,  nearly  all  the  operators  would 
employ  a  process  of  their  own  devising,  and  that,  although  most 
would  work  upon  similar  lines,  yet  the  details  would  be  so  different 
as  to  cause  a  very  wide  divergence  in  the  finished  results. 
(2)  By  the  fact  that,  in  commercial  mixtures  of  carbolic  acid  and 
the  higher  phenols,  the  commonly  adopted  methods  come  entirely  to 
grief. 
The  process  of  KoppeSchaar  (although  we  continually  meet  with 
some  one  who  has  modified  it  so  as  to  render  it  perfect)  is  totally  un- 
reliable for  commercial  use,  because  it  is  full  of  pit-falls.  For  ex- 
ample, to  begin  with,  we  have  the  necessity  of  working  on  such  small 
quantities  that  any  experimental  error  is  multiplied  by  something  like 
1000  ;  and  then,  as  we  are  really  to  a  great  extent  precipitating  cresol 
and  calculating  it  as  phenol,  we  cannot  on  the  face  of  such  a  fact 
expect  much  truth  in  the  result.  This  is  not,  however,  all  because 
the  process  is  not  to  be  depended  upon  even  when  dealing  with  pure 
medicinal  acid.  One  may  set  to  work  to  make  a  series  of  test  experi- 
ments, and  may  theorise  that,  if  it  can  only  be  arranged  so  that  we 
work  with  the  same  excess  of  bromine  and  for  the  same  time,  we  are 
bound  to  get  concordant  results.  If  any  one  has  succeeded  in  really 
carrying  such  reasonable  theory  into  practice  without  meeting  with 
some  unaccountable  differences  in  the  very  first  long  series  of  experi- 
ments, then  he  has  been  much  more  lucky  than  we  have  ever  been, 
1  Abstract  of  a  paper  published  in  The  Analyst,  October,  1887. 
