5oo  Dakin  or  Carrel-Dakin  Solution.    { ^o/ember^?1" 
tion  is  complete.  The  number  of  mils  used  multiplied  by  0.03725 
will  be  the  weight  of  sodium  hypochlorite  in  100  mils  of  the  solu- 
tion; in  other  words  the  percentage,  weight  in  volume,  of  sodium 
hypochlorite. 
To  determine  absence  of  free  caustic  alkali  in  the  finished  solu- 
tion sprinkle  on  the  surface  of  20  mils  of  the  solution  about  0.2 
Gm.  of  phenolphthalein.   No  red  coloration  should  appear. 
In  the  preparation  of  the  solution  only  the  highest  grade  of 
chemicals  should  be  used.  It  is  a  matter  of  record  that  nearly  all 
of  the  unfavorable  reports  concerning  the  value  of  this  method  of 
wound  sterilization  were  undoubtedly  due  to  the  use  of  impure 
chemicals  or  else  negligence  in  the  preparation  of  the  solution.  It 
has  been  the  writer's  experience  that  it  more  than  pays  to  use  the 
purest  procurable  ingredients  in  the  manufacture  of  this  exceedingly 
useful  addition  to  the  surgeon's  armamentaria. 
Concerning  the  stability  or  permanence  of  this  solution  it  has 
been  proven  that  when  kept  in  a  cool,  dark  place  it  deteriorates  very 
slowly.  A  solution,  assaying  0.49  per  cent,  sodium  hypochlorite  on 
the  day  of  its  preparation,  at  the  end  of  three  months'  storage  in 
a  well-stoppered  bottle  kept  in  a  cool,  dark  place,  showed  a  content 
of  0.47  per  cent,  sodium  hypochlorite.  The  same  solution,  kept  two 
months  longer  under  the  same  conditions,  assayed  slightly  less  than 
0.44  per  cent.,  or  one  degree  under  its  specified  strength. 
Despite  this  fact  it  is  always  policy  to  dispense  only  a  recently 
prepared  solution  and  this  is  customary  in  the  larger  institutions, 
where  the  preparation  and  standardization  of  this  solution  has  be- 
come part  of  the  day's  routine  work. 
AX  IMPROVED  APPARATUS  FOR  APPLYING  CARREL- 
DAKIN  SOLUTION  OR  HYPERTONIC  SALT  SOLU- 
TION ACCORDING  TO  THE  METHOD  OF 
WRIGHT,  TANNER  AND  MATSON.1 
By  Paul  S.  Pittenger,  Phar.D. 
In  order  to  make  proper  use  of  the  Carrel-Dakin  solution  or 
hypertonic  salt  solution  for  the  disinfection  of  wounds,  it  is  neces- 
sary to  have  a  suitable  form  of  apparatus  for  holding  the  solution 
1  The  Lancet,  November  11,  1916. 
