ON  HYDKATED  SESQUI- OXIDE  OF  IRON. 
105 
Take  of  (proto)  sulphate  of  iron,  (well  crystallized,)  sixty-four 
ounces  Troy. 
Sulphuric  acid,  seven  fluid  ounces. 
Nitric  acid,  sp,  gr.  138,  twelve  fluid  ounces. 
Water,  a  sufficient  quantity. 
Reduce  the  sulphate  of  iron  to  moderately  fine  power  in  an  iron 
mortar,  mix  together  the  acids  and  five  fluid  ounces  of  water, 
put  the  mixture  in  a  large  porcelain  capsule  on  the  sand  bath  or 
other  regular  source  of  heat,  and  add  the  powdered  sulphate,  about 
two  ounces  at  a  time,  stirring  after  each  addition,  till  the  effer- 
vescence ceases,  until  all  has  been  added,  and  the  elimination  of 
nitrous  fumes  has  ceased.  In  the  absence  of  a  porcelain  capsule 
and  sand-bath,  the  operator  may  use  a  gallon  glass  jar  supported  in 
a  vessel  of  boiling  water  ;  in  either  case,  the  vessel  should  be  large 
enough  to  allow  for  active  effervescence,  and  it  is  hardly  necessary 
to  say  that  the  operation  should  be  performed  under  a  chimney- 
hood,  or  in  the  open  air,  to  avoid  the  noxious  fumes  of  nitrous 
acid.  The  dense  solution  thus  obtained  should  then  be  diluted 
with  water  until  it  measures  four  and  a  half  pints,  (wine  measure,) 
and  then  filtered  through  thick  muslin. 
Solution  of  ter-sulphate  of  iron  thus  prepared,  has  a  dark,  red- 
dish-brown color  in  quantity,  the  specific  gravity  of  1.587  at60°F., 
but  little  if  any  odor,  a  powerful  styptic  taste,  and  mixes  readily 
with  water,  so  as  to  form  a  solution  with  more  color  in  proportion 
to  its  dilution  than  the  strong  liquid.  Each  fluid  ounce  of  this  solu- 
tion contains  a  fraction  more  than  120  grains  of  sesqui-oxide  ;  each 
fluid  drachm  15  grains,  and  each  minim  a  quarter  of  a  grain  ;  and 
as  it  is  equally  applicable  for  preparing  the  oxide  for  chemical  as 
for  antidotal  purposes,  this  correspondence  of  weights  with 
measures  gives  great  facility  in  calculating  any  precise  quantity 
desired. 
It  is  this  solution  which  I  have  proposed  should  be  kept  by 
every  apothecary  as  the  source  of  hydrated  sesqui  oxide  of  iron. 
Its  strength  is  such  that  it  requires  about  an  equal  measure  of 
commercial  solution  of  ammonia  (sp.  gr.  .940,)  to  decompose  it. 
The  apothecary  who  is  suddenly  called  upon  for  the  antidote  will 
proceed  in  the  following  manner  : 
Take  of  Solution  of  ter-sulphate  of  iron,  half  a  pint. 
Solution  of  ammonia,  half  pint,  (or  a  sufficient  quantity. 
"       Water,  a  sufficient  quantity. 
