A%i0ruch^892ym-}       Action  of  Hydrogen  Peroxide,  125 
for  this  purpose  it  was  not  convenient  to  measure  the  evolved  gas 
but  the  more  convenient  plan  was  followed  of  allowing  the  gas  to 
displace  water  and,  after  the  cessation  of  the  reaction,  to  measure 
the  water  displaced.  Two  wide-mouth  bottles  were  arranged  for 
this ;  one,  a  four-ounce  bottle  used  as  a  generator  was  fitted  with  a 
singly  perforated  cork,  through  which  passed  a  piece  of  glass 
tubing ;  the  other,  an  eight-ounce  bottle  filled  with  the  water  to  be 
displaced,  was  fitted  with  a  doubly  perforated  cork  containing  two 
pieces  of  glass  tubing  (one  of  which  by  a  short  section  of  rubber  tubing 
was  connected  with  the  generator;  to  the  other  was  connected  a 
piece  of  rubber  tubing  so  that  this  reached  to  the  bottom  of  an 
eight-ounce  beaker).  24  cc. -hydrogen  peroxide  were  placed  in  the 
generator;  one  cc.  solution  of  ferric  chloride  (U.  S.  P.)  was  measured 
into  a  one  drachm  homoeopathic  vial  and  this  placed  upright  in  the 
generator  so  that  the  two  solutions  could  not  mix ;  before  corking 
the  generator  a  little  of  the  water  from  the  8  oz.  bottle  was  allowed 
to  run  out  through  the  rubber  tubing  so  that  the  latter  was  com- 
pletely filled  with  water ;  after  corking  and  ascertaining  that  the  con- 
nections were  tight,  the  rubber  tubing  from  the  eight-ounce  bottle  was 
introduced  into  the  dry  beaker  and  then  the  ferric  chloride  solution 
and  hydrogen  peroxide  allowed  to  mix  by  tilting  the  generator. 
The  deepening  in  color  is  also  noticeable  in  this  case;  after  a  few 
minutes  gas  bubbles  are  seen  to  escape  and  the  mixture  becomes 
warm  (the  heat  developed  in  this  reaction  is,  however,  not  so  great 
as  in  the  presence  of  alcohol) ;  agitation  favors  the  evolution  of  the 
gas  and  the  reaction  is  then  complete  in  from  one  to  one  and  a  half 
hours;  after  allowing  to  cool  the  displaced  water  measured  182  cc. 
The  examination  of  the  solution  for  iron  salts  gave  the  same  results 
as  in  the  case  of  the  prescription.  The  changes  taking  place  in  the 
prescription  are,  therefore,  as  follows :  The  deepening  of  the  color 
is  due  at  least  in  part  to  the  elevation  of  temperature  (if  the  mixture 
after  cooling  be  warmed  again  there  will  be  produced  a  distinct 
deepening  of  the  color),  and  the  latter  is  due  in  part  to  the  libera- 
tion of  oxygen  from  the  hydrogen  peroxide  caused  by  the 
decomposing  action  of  ferric  chloride  (this  salt,  however,  is  not  in 
any  way  changed),  and  in  part  to  the  oxidation  of  the  alcohol  to 
aldehyde  and  acetic  acid  by  the  nascent  oxygen.  The  presence  of 
alcohol  in  the  tincture  of  iron,  therefore,  accounts  for  the  difference 
in  action  between  the  tincture  of  iron  and  solution  of  iron  upon 
hydrogen  peroxide. 
