NEW  PROCESS  FOR  LIQUOR  FERRI  NITRATIS.  307 
formed,  and  when  its  color  is  blackish  brown  it  is  due  to  the  pre- 
sence of  a  portion  of  proto-nitrate  in  addition.  In  the  following 
process,  which  is  based  on  that  for  making  the  officinal  solution  of 
sesquisulphate  of  iron,  (used  in  preparing  hydrated  sesqui-oxide,) 
a  nitrate  of  the  protoxide  of  iron  is  first  made,  and  then  as  much 
nitric  acid  added  to  the  solution  as  will  convert  the  protoxide 
into  sesqui-oxide  of  iron,  and  this  into  ter-nitrate.  It  is  as 
follows : 
Take  of  Iron  wire,  (card  teeth  or  small 
"         nails,)  three  ounces,  Troy. 
"      Nitric  Acid,  (sp.  gr.  1.42,)         five  fluid  ounces. 
tf     Water,  a  sufficient  quantity. 
Mix  three  fluid  ounces  of  the  nitric  acid  with  half  a  pint  of 
water,  and  add  it  gradually  in  small  portions  at  a  time  to  the 
iron  previously  mixed  with  a  pint  of  water,  observing  to  moderate 
the  reaction  by  setting  the  vessel  in  cold  water.  In  this  way 
the  iron  is  protoxidized  at  the  expense  of  the  water,  and  hydro- 
gen is  evolved  without  the  development  of  red  fumes,  which, 
when  they  occur,  indicate  a  decomposition  of  a  part  of  the  nitric 
acid.  When  all  the  acid  has  been  added,  the  solution  should  be 
repeatedly  agitated  with  the  excess  of  iron,  until  on  filtering  a 
portion  it  has  a  light  green  color,  and  with  ammonia  affords  a 
greenish  white  precipitate.  It  is  now  filtered  into  a  half  gallon 
flask,  and  the  remainder  (f.^ij.)  of  the  nitric  acid  added,  which 
converts  it,  with  violent  effervescence  and  the  escape  of  red 
nitrous  vapors,  into  ter-nitrate  of  sesqui-oxide  of  iron.  The 
liquid  should  now  be  gently  heated  to  deprive  it  of  the  absorbed 
gas,  diluted  until  it  measures  three  pints,  and  filtered  through 
paper. 
Thus  prepared,  »  solution  of  nitrate  of  iron"  has  a  pale  straw 
color,  a  density  of  1.098,  strong  astringent  acid  taste,  affords 
pure  sesqui-oxide  on  the  addition  of  ammonia,  and  will  keep 
without  any  tendency  to  change.  Its  appearance  is  uniform, 
and  in  all  respects  it  is  a  more  reliable  preparation  than  the 
variable  one  made  by  the  formula  of  Kerr.  It  has  been  used 
satisfactorily  at  the  Pennsylvania  Hospital  during  the  last  two 
months,  and  possesses  the  valuable  properties  appropriate  to 
the  officinal  solution  when  well  made. 
June,  1857. 
