498  Dakin  or  Carrel-Dakin  Solution.    {  Ang Jember  ^g™' 
acid  in  its  preparation.  This  preparation  was  found  objectionable 
however,  due  to  its  irritating  qualities  which  were  later  attributed 
to  the  boric  acid.  It  was  Daufresne,  a  French  scientist,  who  sug- 
gested the  modification  whereby  the  boric  acid  was  advantageously 
replaced  by  sodium  bicarbonate.  It  is  the  Daufresne  modification  of 
the  original  Dakin  formula  that  is  used  now  in  the  preparation  of 
Dakin  or  Carrel-Dakin  solution. 
While  much  has  been  printed  in  the  various  journals  concerning 
the  history,  preparation  and  standardization  of  this  solution,  it  is 
to  be  regretted  that,  in  several  instances,  the  matter  has  been  pre- 
sented in  a  complicated  form,  much  important  data  being  left  to  the 
imagination  of  the  reader  and  in  other  instances  errors  seem  to  have 
crept  into  the  text.  It  is,  therefore,  with  the  intention  of  simplify- 
ing the  text  and  explaining  certain  obscure  points  that  this  article 
is  presented.  It  is  an  attempt  to  outline  the  proposition  in  straight 
lines  instead  of  hyperbolas. 
The  Carrel-Dakin  solution  is  essentially  a  solution  of  sodium 
hypochlorite  which  must  be  free  from  caustic  alkali.  It  must  con- 
tain between  0.45  per  cent,  and  0.50  per  cent,  of  sodium  hypochlorite 
(not  available  chlorine  as  stated  in  some  of  the  published  papers  on 
the  subject,  and  upon  which  the  assay  process  of  the  U.  S.  P.  IX 
for  Liquor  Sodse  Chlorinatae  is  based). 
Another  error  noticed  is  the  assumption  that  the  chlorinated 
lime  on  the  market  contains  25  per  cent,  chlorine,  while  as  a  matter 
of  fact  the  Pharmacopoeia  specifies  that  chlorinated  lime  shall  con- 
tain "  not  less  than  30  per  cent,  of  available  chlorine."  In  the  writ- 
er's judgment  it  would  seem  more  logical  to  write  the  general  for- 
mula assuming  that  the  lime  is  nearer  to  30  per  cent,  strength  than 
to  25  per  cent.  A  grocery  store  sample  recently  examined  showed 
over  35  per  cent. 
Reverting  to  the  content  of  hypochlorite  in  this  solution  it  might 
be  well  to  state  here  that  under  0.45  per  cent,  the  solution  is  not 
active  enough  and  above  0.50  per  cent,  it  is  irritant. 
Using  chlorinated  lime  of  30  per  cent,  chlorine  content  the  fol- 
lowing formula  is  used  to  prepare  ten  liters  of  solution, — 
Chlorinated  lime    154  Gm. 
*  Sodium  carbonate  dried    77  Gm. 
Sodium  bicarbonate    64  Gm. 
*  If  the  monohydrated  sodium  carbonate  is  used  take  90.5  Gm.  or  if  the 
crystal  sodium  carbonate  is  used  take  200  Gm. 
