32 
LIQUOR  FERRI  TERSULPHATIS. 
mixture  of  two  salts  already  known ;  and  secondly,  whether  it 
possesses  any  advantages  over  the  normal  salt  as  a  remedial 
agent. 
With  regard  to  the  first  question,  the  writer  believes  this  to 
be  a  new  and  distinct  combination  of  the  acid  and  base,  for  the 
two  following  principal  reasons :  Where  the  dilute  solution  is 
precipitated  by  ammonia,  the  ammonia  being  kept  always  iu  ex- 
cess to  avoid,  as  far  as  possible,  the  formation  of  sub-salts,  an 
ochrey,  heavy  precipitate  is  obtained,  which  is  almost  absolutely 
insoluble  in  hydrochloric  acid.  Again,  the  reaction  with  con- 
centrated sulphuric  acid,  pointed  out  by  M.  Monsel,  is  very 
characteristic,  and,  as  far  as  the  writer  knows,  does  not  belong 
to  either  of  the  salts  already  known. 
Whether  its  remedial  agency  is  peculiar  to  it  as  a  sub-salt  in 
contradistinction  to  the  normal,  or  so-called  neutral  salt,  the 
writer  cannot  state  from  either  experiment  or  observation,  but 
he  is  decidedly  of  the  opinion  that  to  its  minus  proportion  of 
acid  belongs  that  peculiar  property  or  quality  which  renders  it 
so  very  nearly  innoxious  and  unirritating  to  the  living  tissues. 
He  has  seen  it  repeatedly  applied,  of  full  strength,  to  grave 
wounds  without  any  irritant  effect,  and  it  has  been  repeatedly 
injected  into  varicose  veins,  and  been  quietly  absorbed  with  the 
clot,  without  either  local  or  general  irritation. 
Within  the  observation  of  the  writer,  in  the  hands  of  his  pro- 
fessional friends,  it  has  been  instrumental  in  arresting  the  most 
difficult  and  troublesome  hemorrhages  ;  and  has  been  freely  used 
internally,  as  well  as  externally,  with  good  results. 
Dentists  also  find  it  a  valuable  agent  in  the  practice  of  their 
art;  and  in  the  treatment  of  spongy  gums,  hemorrhages,  &c,  it 
appears  to  have  taken  a  place  hitherto  vacant ;  and  yet  in  the 
absence  of  direct  comparative  experiment,  it  would  be  impossible 
to  assert  that  a  solution  of  the  normal  salt  would  be  less  effec- 
tive. 
As  the  formula  of  the  writer  differs  a  little  from  those  of  M. 
Monsel  and  Prof.  Procter,  in  being  more  simple  and  easy,  it 
may  be  worth  while  to  offer  it  for  trial,  adopting  for  this  prepa- 
ration the  name  of  persulphate,  in  contradistinction  to  the  nor- 
mal tersulphate. 
