LIQUOR  FERRI  TERSULPHATIS.  81 
color,  odorless,  but  with  an  acid  astringent  taste.  It  has  a 
s.  g.  of  1*66,  and  in  composition  is  as  follows  : 
Fe2  Os  =  80  X  1  -  80  =  20  per  cent.  |^e'  X|  Pertc4ent- 
3S03  =   40  X  3  =120  =  30  " 
22-22HO  =  9x22-22=  200  =  50  "  
Fe2  03  3S03  4-22-22HQ  g  400  =100  
Its  known  and  accurate  composition  when  thus  made,  and  the 
decimal  quality  of  the  figures  which  express  its  strength,  render 
it  very  convenient  in  practice. 
Each  part  of  the  solution  is  equivalent  to  0-695  parts  of  crys- 
tallized sulphate  of  protoxide — or  one  part  of  crystallized  sul- 
phate of  protoxide  is  equivalent  to  143885  parts  of  the  solu- 
tion. 
Each  part  of  the  solution  is  saturated  by  1*275  parts  of  offici- 
nal liquor  ammoniae,  or  by  -85  part  of  a  solution  containing  15 
per  cent,  of  ammoniae,  the  commercial  ammonia  being  about  this 
strength,  or  s.  g.  -940. 
Thus  when  the  hydrated  oxide  is  to  be  prepared  from  it, 
whether  for  antidote  or  other  purposes,  eight  parts  of  the  solu- 
tion— say  eight  ounces,  as  about  the  proper  quantity  for  the 
antidote,  ten  and  a  quarter  ounces  of  liquor  ammonite,  or  six 
and  eight-tenth  ounces  of  commercial  ammonia  will  precipitate 
it  perfectly.  When  to  be  used  instead  of  the  sulphate  of  pro- 
toxide, in  such  a  formula  as  the  Ferri  et  Potassae  Tartras,  for  in- 
stance, 11-51079  ounces  is  to  be  taken— or  more  practically,  as 
there  is  an  excess  of  sesquioxide  provided  by  the  formula — eleven 
and  a  half  ounces,  as  the  equivalent  of  the  eight  ounces  of  crys- 
tallized sulphate  of  protoxide,  directed  in  the  formula. 
Another  solution  of  sulphate  of  sesquioxide  of  iron,  of  different 
composition,  has  lately  been  employed  in  medicine  and  surgery 
with  effects  so  well  marked,  and  now  so  well  established  here, 
that  there  appears  to  be  no  doubt  of  the  propriety  of  introducing 
it  among  the  officinal  preparations.  It  is  the  styptic  and  haemos- 
tatic solution  of  M.  Monsel,  of  Bordeaux.  In  a  paper  upon 
this  preparation,  by  Prof.  Procter,  in  the  September  number  of 
this  Journal,  the  questions  are  raised :  first,  as  to  whether  the 
salt  of  Monsel's  solution  is  a  definite  chemical  compound,  or  a 
