356 
NOTE  ON  CARBOLIC  ACID,  ETC. 
Two  solutions  of  this  creasote  may  be  usefully  recognized 
and  established  as  sufficient  for  all  its  general  uses,  whether 
sanitary  or  medicinal.  One  may  be  called  a  saturated  solution, 
and  the  other  a  standard  solution,  such  having  been  used  under 
these  names  to  some  extent  in  the  army  and  in  some  large  hos- 
pitals and  found  convenient,  during  some  years  past. 
The  saturated  solution  is  made  by  shaking  five  measures  of 
the  creasote  with  one  hundred  measures  of  water,  and  filtering 
the  solution  off  through  two  or  three  thicknesses  of  wet  paper. 
It  is  not  necessary  that  the  water  should  be  warm,  indeed  it  is 
better  used  at  ordinary  temperatures,  because  the  filtrate,  which 
is  apt  to  become  turbid  or  milky  at  best,  becomes  much  more 
so  in  proportion  as  it  is  cooled  down  below  the  temperature  at 
which  it  was  filtered.  This  milkiness,  though  unsightly,  is  of 
no  practical  importance,  and  may  be  disregarded  in  most  of  the 
uses  to  which  the  solution  is  applicable.  V/hen  applied  to  nicer 
uses  it  may  be  filtered  a  second  time,  after  standing.  If  the 
creasote  be  not  very  thoroughly  purified  the  solutions,  on  expo- 
sure to  light,  become  of  a  pinkish  or  reddish  tinge,  which  ren- 
ders them  inelegant,  to  say  the  least.  The  saturated  solution 
will  contain  from  2  to  5  per  cent,  of  the  creasote  in  proportion 
as  the  latter  consists  mainly  of  the  one  Phenol  or  the  other. 
As  the  creasote  commonly  occurs,  it  will  contain  about  4  per 
cent.,  while  if  made  from  the  crystallized  Phenol  or  crystal- 
lized carbolic  acid,  it  will  contain  5  per  cent.,  and  will  not 
be  strictly  a  saturated  solution,  since  water  at  summer  tem- 
peratures takes  up  about  6*6  per  cent,  of  the  crystals,  and 
makes  a  perfectly  clear  and  colorless  solution  even  without  fil- 
tration. At  low  temperatures,  however,  these  solutions  become 
milky  if  holding  more  than  5  per  cent.  Hence  5  per  cent,  was 
fixed  upon  as  the  maximum  strength  for  what  is  called  satu- 
rated solution.  In  the  management  of  the  crystallized  Phenol 
(carbolic  acid)  for  dispensing,  it  is  perhaps  the  best  practice, 
on  buying  a  pound  bottle  of  it,  to  melt  it  by  setting  it 
in  water  at  about  37°  C.  or  100°  F.,  and  then  add  water  in  the 
proportion  of  one^  fluidounce  to  the  avoirdupois  pound.  It  will 
then  remain  permanently  liquid  except  at  very  low  tempera- 
tures, and  should  be  dispensed  by  measure,  being  still  used  as 
