NOTE  ON  CARBOLIC  ACID,  ETC. 
353 
NOTE  ON  THE  SO-CALLED  CARBOLIC   ACID,  OR  COAL 
TAR  CREASOTE. 
By  Edward  R.  Squibb,  M,  D. 
(Continued  from  page  270.) 
Neither  color,  consistence,  nor  odor,  however,  can  be  relied 
upon  as  any  useful  indication  of  real  value,  but  it  happens  that 
there  is  one  very  simple  and  very  easy  test  of  value  which  is 
infallible.  All  the  useful  tar  phenols  are  entirely  soluble  in 
water,  while  the  useless  substances  with  which  they  are  naturally 
associated  are  not, — -at  least  to  any  practical  extent.  But  as 
some  of  the  phenols  require  a  large  proportion  of  water  to  dis- 
solve them  the  water  in  testing  them  should  always  be  taken  in 
excess.  A  fluidounce  of  the  creasote  well  shaken  with  one  gallon 
of  water,  and  the  whole  passed  through  a  small  filter  of  two  or 
three  thicknesses  of  good  filtering  paper  well  wetted  in  the 
funnel  at  the  time  of  using,  will  decide  its  quality  at  once,  and 
the  proportion  of  insoluble  oily  matters  which  do  not  pass  through 
the  filter  may  be  roughly  estimated  when  in  sufficient  quantity, 
by  breaking  the  point  of  the  filter  over  a  graduate  measure.  The 
creasote,  when  of  good  quality,  should  contain  from  90  to  96  per 
cent,  soluble  in  this  proportion  of  water,  and  then  the  residue 
which  will  not  pass  the  wet  filter  is  too  small  to  be  roughly 
measured,  though  very  easily  seen,  estimated,  and  compared  with 
residues  from  other  samples.  Much  of  the  impure  carbolic  acid, 
or  the  badly  named  '^solution  of  carbolic  acid,"  contains  less 
than  90  percent,  of  soluble  phenols,  while  the  so-called  crude  car- 
bolic acid  of  the  market  varies  very  much,  samples  being  met  with 
of  all  values,  from  10  or  15  per  cent,  up  to  50  or  60  per  cent. 
These  are  all  proportionately  useful  for  disinfectant  purposes, 
and,  when  properly  managed,  for  medical  uses  also,  as  far  as 
they  go.  But  they  are  greasy,  tarry,  dirty  mixtures,  difficult  of 
management  by  ordinary  means,  and  should  therefore  generally 
be  rejected  for  common  uses,  and  always  when  for  medical  uses. 
In  applying  the  test  of  solubility  to  the  creasote  to  determine  jts 
value,  it  must  be  remembered  that  in  the  interest  of  profit  or 
gain,  fraud  may  be  practiced,  but  for  the  present  it  is  generally 
sufficient  to  see  that  the  creasote  to  be  tested  is  neither  acid  nor 
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