ON  THE  MEDICINAL  HYPOPHOSPHITES. 
121 
Take  of  Hypophosphite  of  lime    .       .       .       6  oz. 
Sesqui-carbonate  of  ammonia  (translucent)  7«23  oz. 
Water,  a  sufficient  quantity. 
Dissolve  the  lime  salt  in  four  pints  of  water,  and  the  ammonia 
salt  in  two  pints  of  water,  mix  the  solutions,  drain  the  resulting 
carbonate  of  lime,  and  wash  out  the  retained  solution  with  water. 
The  filtrate  should  then  be  evaporated  carefully  to  dryness, 
then  dissolved  in  alcohol,  filtered,  evaporated  and  crystallized. 
This  salt  is  deliquescent  in  the  air,  very  soluble  in  alcohol  and 
water,  and  when  carefully  heated  evolves  ammonia,  and  leaves 
hydrated  hypophosphorus  acid.  The  composition  of  this  salt  is 
NH3+2HO,PO. 
Hypophosphite  of  Sesquioxide  of  Iron  This  salt  may  be 
obtained  in  the  form  of  a  white  gelatinous  hydrate,  by  pre- 
cipitating a  solution  of  hypophosphite  of  soda  or  ammonia 
with  one  of  sesqui-sulphate  of  iron.  The  precipitate  should  be 
well  washed  with  water  and  dried  at  a  moderate  temperature. 
It  is  necessary  to  avoid  using  a  hypophosphite  containing  any  al- 
kaline carbonate  or  the  precipitate  will  be  contaminated  with 
free  sesquioxide.  Thus  prepared,  this  salt  is  a  white,  amor- 
phous, tasteless  powder,  like  the  pyrophosphate,  soluble  in  hy- 
drochloric acid,  and  in  free  hypophosphorous  acid. 
Eypophosphorous  Acid. — So  far  as  we  are  aware,  this  acid  has 
not  been  employed,  in  a  free  state,  by  Dr.  Churchill,  but  it  is 
highly  probable  that  it  may  come  into  use,  should  the  favorable 
results  claimed  for  its  salts  be  substantiated  by  new  observations. 
Any  claims  which  phosphoric  acid  may  possess  as  an  agent  to 
supply  the  waste  of  phosphorus  and  phosphates  in  the  human 
economy,  will  be  more  than  equalled  by  this  acid.  Hypo- 
phosphate  of  baryta  is  the  salt  which  is  most  eligible  for  the 
preparation  of  this  acid,  but  it  is  more  convenient  to  prepare  it 
from  the  lime  salt,  viz  : — 
Take  of  Hypophosphite  of  lime       .       .       480  grains. 
Crystallized  Oxalic  acid      .       .       350  grains. 
Distilled  water    ....  9  fluid  oz. 
Dissolve  the  hypophosphite  of  lime  in  six  ounces  of  the  water 
and  the  acid  in  the  remainder,  with  the  aid  of  heat,  mix  the 
solutions,  pour  the  mixture  on  a  white  paper  filter,  and  when  the 
