64         PREPARATION  AND  USE  OF  PERCHLORIDE  OF  IRON. 
Under  the  influence  of  this  liquid  all  the  blood  within  a  distance 
of  three  or  four  centimetres  is  converted  in  a  few  minutes  into  a 
solid  clot.  This  new  mode  of  treatment,  however,  is  only  now 
being  tested. 
It  has  not  jet  been  determined  what  is  the  real  mode  of  ac- 
tion of  perchloride  of  iron  in  the  blood.  According  to  some,  it 
coagulates  the  whole  of  the  blood  and  all  its  elements.  Accord- 
ing to  others,  it  acts  only  on  the  fibrine,  and  others  again  con- 
tend that  its  action  is  confined  to  the  albumen.* 
It  still  remains  to  be  shown  what  is  the  nature  of  the  clot, 
whether  the  perchloride  is  a  simple  hemostatic  or  a  hemospasic, 
whether  it  acts  as  an  irritant  caustic  or  as  a  toxic  agent,  and, 
moreover,  what  is  the  maximum  dose  that  can  be*  safely  applied. 
It  will  be  seen  from  these  questions,  which  have  been  recently 
discussed  in  the  Academy  of  Medicine,  that  some  importance 
attaches  to  the  preparation  of  perchloride  of  iron.  M.  Burin 
de  Buisson,  who  made,  with  M.  Pravaz,  the  first  experiments 
with  the  new  mode  of  treatment  to  which  reference  has  been 
made,  prepared  in  the  following  manner  the  chloride  which  they 
used.  Peroxide  of  iron,  previously  heated  to  redness,  was  di- 
gested without  heat  for  five  or  six  hours  with  colorless  and  pure 
hydrochloric  acid ;  the  mixture  was  then  heated  over  a  water- 
bath,  until  about  two  hundred  parts  of  the  oxide  were  dissolved 
in  1000  parts  of  acid.  The  process  should  be  conducted  with  a 
porcelain  capsule  the  weight  of  which  is  known.  The  liquid 
having  been  decanted  from  the  undissolved  oxide  was  carefully 
evaporated  over  a  water-bath,  stirring  it  continually  until  it  ac- 
quired the  consistence  of  a  thick  syrup,  the  weight  of  which  was 
determined.  This  was  mixed  with  half  its  weight  of  distilled 
water,  heated  for  a  short  time,  and  then  filtered.  The  capsule 
and  filter  were  washed  with  a  quantity  of  water  equal  to  that 
previously  used,  and  the  whole  subsequently  brought  to  the  den- 
sity of  43.5°  or  44°. 
The  chloride  prepared  in  this  way  is  subject  to  the  objection 
*  M.  Burin  du  Buisson  has  ascertained  that  ten  drops  of  solution  of 
perchloride  of  iron,  of  45°,  added  to  the  white  of  an  egg  diluted  with 
thirty  grammes  of  water  causes  the  whole  to  become,  in  fifteen  seconds,  a 
mass  which,  on  inverting  the  vessel  in  which  it  is  contained,  remains  ad- 
hering to  the  sides,  and  will  not  fall  out  for  some  time. 
