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RESEARCHES  OF  HYPOPHOSPHITE  OP  LIME. 
EESEARCHES  ON  HYPOPHOSPHITE  OF  LIME, 
By  M.  Gerard  Janssen. 
1.  Preparation. 
The  hypophosphites  are  seldom  met  with  chemically  pure  ;  this 
is  due  to  those  terrible  explosions  to  which  the  most  skilful  op- 
erator exposes  himself  in  their  preparation  ;  prompted  by  a  well- 
grounded  fear,  he  dares  not  conduct  the  process  to  the  end,  and 
the  product  obtained  is  more  or  less  altered  by  foreign  sub- 
stances. 
The  properties  attributed  to  such  preparations  cannot  be  those 
of  the  hypophosphites  chemically  pure.  The  author  of  these  re- 
searches sought  a  new  method  of  preparation,  which  would  per- 
mit of  obtaining  these  salts  perfectly  pure  and  without  danger. 
He  first  investigated  the  causes  of  explosion  ;  these  he  found 
to  be  due  to — 1st,  the  action  of  heat,  and  the  oxygen  of  the  air 
on  the  phosphuretted  hydrogen  (P  H3) ;  2nd,  the  production  of 
biphosphuretted  hydrogen  (P2  H) ;  3rd,  the  formation  of  a  pecu- 
liar and  very  explosive  compound,  to  which  he  gives  the  name  of 
triphosphuretted  bi-hydride  (P3H2).  This  substance  crystallizes 
in  hexagonal  prisms.  As  long  as  the  temperature  of  the  mix- 
ture remains  constant,  there  is  no  fear  of  explosion,  but  if  after 
the  heat  has  decreased  it  be  then  raised,  the  triphosphuretted 
bi-hydride  is  instantly  decomposed  into  phosphorous  and  phos- 
phuretted bi-hydride  (P  H2),  which  takes  fire  spontaneously. 
Alcohol  is  the  only  compound  which  prevents  these  explosions, 
because  it  not  only  arrests  ?the  action  of  the  oxygen  of  the  air 
on  the  phosphuretted  hydrogen  and  the  production  of  biphos- 
phuretted hydrogen,  but  also,  what  is  more  important,  the  for- 
mation of  phosphuretted  bi-hydride. 
To  prepare  the  hypophosphite  of  lime,  which  may  be  taken 
as  a  type  of  these  salts,  a  sufficient  quantity  of  hydrate  of  lime 
is  mixed  with  three  times  its  weight  of  distilled  water,  to  which 
a  third  of  pure  alcohol  has  been  added.  The  mixture  is  intro- 
duced into  a  long-necked  flask  heated  gently  in  a  sand-bath* 
When  the  mixture  has  attained  a  temperature  of  50°  to  60° 
Cent.,  small  pieces  of  phosphorous  are  gradually  added,  until 
the  action  has  entirely  ceased.  The  apparatus  is  allowed  to  cool, 
and  the  solution  filtered  through  asbestos.    The  filtered  liquid  is 
