212  Liquor  Cresolis  Compositus,  U.S. P.     { A%iay?Sarm" 
LIQUOR  CRESOLIS  COMPOSITUS,  U.S.P. 
By  Ferdinand  Nitardy.1 
This  preparation  has  been  subject  to  considerable  criticism,  and 
various  suggestions  toward  improvement  have  been  made.  The 
chief  cause  of  criticism  is  the  fact  that  the  U.S.P.  formula  will  not 
give  a  clearly  water-soluble  product.  The  turbidity  is  due  to  un- 
saponified  linseed  oil.  If  the  preparation,  made  according  to  the 
U.S.P.  process,  is  allowed  to>  stand  long  enough,  it  will  become 
clearly  water-soluble,  the  time  required  varying  from  ten  days  to 
six  months,  according  to  the  temperature  at  which  it  is  kept,  and 
the  excess  of  alkali  present.  The  same  result  can  also  be  obtained 
by  heating  the  finished  product  for  three  hours  on  a  water  bath, 
but  this  process  is  inferior  to  the  one  of  completely  saponifying  the 
linseed  oil  before  adding  the  cresol,  as  it  involves  the  loss  of  some 
cresol  by  evaporation,  as  well  as  danger  of  fire,  since  the  cresol 
vapors  are  inflammable. 
The  soap  formed  in  the  U.S.P.  formula  for  Liquor  cresolis  com- 
positus contains  but  14  per  cent,  of  water,  which  is  much  less  than 
the  amount  present  in  ordinary  soft  soap.  The  U.S.P.  soft  soap, 
containing  from  40  to  50  per  cent,  of  water,  for  this  reason  can  not 
be  substituted  for  this  soap.  On  account  of  the  small  quantity  of 
water  present,  saponification  does  not  readily  take  place  in  the  cold. 
The  use  of  water-bath  heat,  and  the  addition  of  a  small  quantity  of 
alcohol,  to  aid  rapid  saponification,  are  advisable.  Under  these  con- 
ditions saponification  is  complete  in  from  five  to  ten  minutes. 
If  the  potassium  hydroxide,  used  in  making  the  soap,  is  of  85 
per  cent,  strength,  the  resulting  soap  is  exactly  neutral  or  but  very 
slightly  alkaline  (the  saponification  number  of  linseed  oil  varies  from 
I92  to  195,  equivalent  to  79  06  to  80-30  grammes  of  potassium  hy- 
droxide required  for  complete  saponification  of  350  grammes  of 
linseed  oil),  but  if  the  potassium  hydroxide  is  of  90  percent,  strength, 
which  may  happen,  since  the  potash  on  the  market  runs  in  strength 
from  85  to  88  and  occasionally  up  to  90  per  cent,  of  KOH,  the 
resulting  soap  will  contain  about  0  5  per  cent,  of  free  KOH. 
A  neutral  soap  is  preferable  for  this  preparation,  but  the  small 
amount  of  free  alkali  that  would  be  introduced  into  the  preparation 
1  Read  before  the  Chicago  Branch  of  the  American  Pharmaceutical  Asso- 
ciation. 
