246 
Commercial  Hypophosphorous  Acid. 
Am.  Jour.  Pharm* 
May,  1887. 
at  60°  F.  The  neutralizing  power,  not  a  very  reliable  test  with  a 
readily  oxidized  acid  like  hypophosphorous  acid,  was  determined  by  a 
quarter  normal  solution  of  NaHO,  using  methyl  orange  as  an  indi- 
cator. 
Ten  cc.  of  the  samples  were  diluted  to  500  cc.  with  distilled  water. 
Ten  cc.  of  the  Jth  NaHO  standard  solution,  which  would  contain  *10 
gram  of  NaHO  equal  to  neutralizing  -165  gram  of  hypophosphorous 
acid,  were  taken,  so  that  the  quantity  of  the  diluted  sample  required 
to  neutralize  this  contained  *1 65  gram  of  the  acid.  In  the  case  of 
sample  A  25  cc.  of  the  1  in  50  solution  were  required,  which  would 
be  equal  to  *5  cc.  of  the  original  sample,  the  specific  gravity  of  which 
was  1*332,  so  that  it  would  weigh  *5666  gram,  and  if  that  contained 
'165  gram  of  acid  a  rule  of  three  sum  decided  that  the  percentage  was 
29*12.  In  making  these  volumetric  estimations  the  ordinary  method,, 
that  of  running  the  standard  solution  into  the  sample,  was  not  fol- 
lowed, it  being  thought  that  having  the  more  dilute  solution  in  the 
burette  would  give  more  exact  results.  Also  that  the  indicator  would 
be  altered  by  remaining  for  any  length  of  time  with  an  excess  of  so 
powerful  a  reducing  acid  as  hypophosphorous. 
Practically,  however,  both  methods  yielded  similar  or  very  nearly 
similar  results. 
As  it  was  thought  that  the  determination  of  the  reducing  power 
of  the  samples  would  be  a  truer  criterion,  a  process  easily  applied 
was  looked  for. 
A  standardized  solution  of  KMn04  would,  it  was  thought,  admi- 
rably suit  the  purpose. 
Various  experiments  were  then  made  in  the  acid  solution  and  neu- 
tralized, but  after  a  series  of  heart-burnings  it  was  found  that  the 
process  would  not  work  practically. 
Though  there  can  be  no  doubt  that  the  official  hypophosphites  can 
be  readily  and  easily  determined  by  this  method  it  must  be  borne  in 
mind  that  in  these  cases  known  quantities  are  operated  upon,  and  the 
end  of  the  reaction  can  be  ascertained  only  by  filtration.  The  idea  of 
using  KMn04  was  therefore  abandoned,  and  fortunately  for  me  the 
resources  of  chemistry  were  not  exhausted.  In  "  Watts'  Dictionary 
of  Chemistry"  a  process  founded  on  the  power  of  hypophosphorous 
acid  of  reducing  HgCl2  to  HgCl  was  unearthed.  It  consists  in  add- 
ing a  known  quantity  of  the  sample  to  an  excess  of  mercuric  chloride,, 
acidifying  with  a  small  quantity  of  HC1,  keeping  the  solution  at  a 
