ON  THE  HYPOPHOSPHITES  OF  IRON. 
313 
of  substituting  the  hypophosphite  of  protoxide  of  iron  for  the 
sesquisalt,  and,  as  will  be  seen  by  reference  to  his  paper,  gives  a 
process  for  making  it  either  by  double  decomposition  between 
sulphate  of  iron  and  hypophosphite  of  lime,  or  by  saturating  the 
aqueous  solution  of  hypophosphorous  acid  by  means  of  recently 
precipitated  protocarbonate  of  iron.  It  may,  also,  be  prepared 
by  saturating  the  solution  of  hypophosphorous  acid  with  iron 
filings,  which  dissolve  in  this  acid  with  the  evolution  of  hydro- 
gen, just  as  in  diluted  SO3,  producing  a  light  greenish  solution, 
which,  by  evaporation  in  vacuo  yields  a  light  green  crystalline 
salt,  easily  effected  by  atmospheric  oxygen. 
The  relative  advantage  of  the  ferrous  and  ferric  hypophos- 
phites  in  medicine  has  not  been  determined,  so  far  as  I  am  aware. 
Nor  am  I  acquainted  with  the  effects  of  time  and  exposure  on 
the  compound  syrup  of  hypophosphites  made  with  the  proto  salt. 
It  is  well  known,  however,  that  the  syrup  prepared  with  the  ses- 
qui  salt  of  iron  slowly  deposits  a  pulverulent  substance  which  is 
partially  attached  to  the  sides  of  the  vessel,  and  which  appears 
to  be  the  result  of  atmospheric  oxidation,  as  when  the  syrup  is 
kept  hermetically  sealed  it  remains  clear.  It  is  probable  that  in 
this  change,  hypophosphite  of  sesquioxide  becomes,  by  the 
absorption  of  oxygen,  phosphate  of  sesquioxide,  which  precipi- 
tates— because  it  is  insoluble  in  hypophosphorous  acid. 
In  a  note  on  this  subject,  in  the  May  number  of  this  Journal, 
I  proposed  a  reduction  in  the  amount  of  sugar,  on  the  ground  of 
its  causing  the  precipitation  of  a  portion  of  what  I  then  supposed 
was  hypophosphite  of  lime.  Subsequently  I  became  convinced, 
by  experiment,  that  this  precipitate  was  at  least  partially  ferru- 
ginous. My  friend  J.  M.  Maisch,  who  also  met  with  a  like  diffi- 
culty, made  an  analysis  of  the  precipitate,  as  the  following  note 
will  show. 
Philadelphia,  May  17,  1858. 
Dear  Sir,-~In  the  last  number  of  the  Amer.  Journ.  of  Pharmacy,  page 
226,  you  state  that  when,  in  preparing  the  syrup  of  hypophosphites,  "  so 
much  as  twelve  ounces  of  sugar  is  used  to  the  pint,  it  is  found  to  cause  a 
precipitation  of  a  portion  of  the  calcareous  hypophosphite"  and  in  accord- 
ance with  this  observation  you  give  another  formula,  by  which  the  employ- 
ment of  heat  in  dissolving  a  much  smaller  quantity  of  sugar  is  obviated. 
In  strict  conformity  with  these  latter  directions,  I  have  lately  made  this 
preparation,  taking  care  to  have  the  water  boiling  hot  for  washing  the 
