MANUFACTURE  OF  NEUTRAL  PER-SULPHATE  OF  IRON.  501 
either  the  Cream  or  Orgeat  Syrups,  especially  as  to  the  last. 
Many  complain  that  the  syrups  separate,  and  I  have  found  it 
true,  both  as  to  some  I  purchase  and  as  to  the  others  I  prepare, 
This  may  be  prevented  by  simply  keeping  it  in  a  bottle  having  a 
good  cork  or  glass  stopper,  and  not  in  one  of  those  mineral  water 
syrup  bottles  having  a  metallic  cover. 
Yours,  respectfully, 
Bradford  Ritter. 
Oct  4th,  1855. 
ON  THE  ECONOMICAL   MANUFACTURE  OF    NEUTRAL  PER- 
SULPHTAE  OF  IRON  ;  AND  OF  DISINFECTING  POWDER. 
By  Campbell  Morfit,  M.  D. 
As  neutral  per-sulphate  of  iron,  when  associated  with  plaster 
and  charcoal,  constitutes  a  most  efficient  deodorizing  and  disin- 
fecting agent ;  and  its  general  use  being,  therefore,  desirable,  the 
following  method,  believed  to  be  new,  is  proposed  for  the  econo- 
mical manufacture  of  it  upon  a  large  scale. 
Dissolve  100  pounds  of  copperas  in  a  sufficient  quantity  of  hot 
water,  and  while  the  solution  is  kept  boiling,  add,  portionwise, 
25  pounds  of  aqua  fortis  ; — taking  care  that  the  intervals  between 
the  portions  shall  be  long  enough  to  allow  the  escape  of  the  red 
fumes  arising  from  the  de-oxidation  of  the  aqua  fortis,  by  the 
iron  salt.  An  acid  mixture  of  per-sulphate  and  nitrate  of  iron 
is  thus  formed. 
To  get  rid  of  the  nitrate  and  the  excess  of  acid,  powdered 
chalk  must  be  stirred  in  until  effervescence  entirely  ceases,  and 
the  whole  left  to  repose  for  some  hours,  when  peroxide  of  iron, 
free  from  manganese,  will  have  precipitated  with  any  redundance 
of  chalk  that  may  have  been  added.  The  latter,  however,  is 
not  in  the  way  for  our  purpose ;  and  it  is,  therefore,  only  neces- 
sary to  draw  off  the  supernatant  liquid  and  wash  once  with  fresh 
water.  The  precipitate  is  then  to  be  diffused  in  boiling  water, 
barety  neutralized  with  oil  of  vitriol,  evaporated,  and  brought  to 
pulverulent  form  by  stirring  in  500  pounds  of  charcoal  dust  and 
2000  pounds  of  ground  plaster,  and  drying  in  air  chambers  or 
by  exposure  to  air. 
If  it  should  be  required  to  make  pure  per-sulphate  of  iron  for 
