244 
Commercial  Hypophosphorous  Add. 
Am.  Jour.  Pharm. 
May,  1887. 
In  Parrish's  "  Pharmacy  "  this  formula  is  reproduced  in  detail,  350 
grains  or  a  sufficiency  of  crystallized  oxalic  acid  being  specified. 
Attfield,  in  his  latest  edition,  says  "  it  may  be  prepared  by  decompos- 
ing the  calcium  salt  by  oxalic  acid,  or,  better,  the  pure  barium  salt 
with  sulphuric  acid." 
Watts'  "Inorganic  Chemistry"  recommends  the  decomposition  of 
the  baric  or  calcic  salts  with  sulphuric  acid,  and  Watts'  "  Dictionary 
of  Chemistry,"  the  baric  salt  with  sulphuric  acid,  or  the  plumbic  salt 
with  sulphydric  acid. 
It  will  thus  be  seen  that  there  is  a  variety  of  methods  for  the  pre- 
paration of  hypophosphorous  acid.  Commercially,  however,  the 
method  recommended  originally  by  Procter  is  the  one,  I  think,  in 
general  use.  At  least,  if  any  reliance  can  be  placed  on  the  result  of 
the  experiments  about  to  be  summarized,  this  would  seem  to  be  a 
logical  conclusion,  as  both  calcium  and  the  oxalic  radicle  were  proved 
to  be  present  in  every  sample  examined. 
As  the  solution  that  suggested  this  note  was  evidently  much 
stronger  in  acid  than  would  result  from  its  preparation  by  Procter's 
formula,  I  resolved  to  obtain  supplies  from  different  sources,  merely 
asking  for  hypophosphorous  acid,  without  demanding  a  certain  per- 
centage, and  in  that  way  making  comparisons,  with  regard  to  their 
strength  and  impurities,  of  which  something  had  been  foreshadowed 
by  the  original  solution.  In  attempting  to  deal  with  these  samples 
as  types  of  the  acid  of  commerce,  I  wish  to  preface  the  communication 
of  the  results  by  stating  that  I  am  well  aware  that  there  is  such  a 
thing  as  medicinal  purity  comparable  to  chemical.  To  be  more  ex- 
plicit, that  economic  considerations  are  as  worthy  of  practical  applica- 
tion by  manufacturing  chemists  as  by  others,  and  that  it  is  unneces- 
sary to  free  a  commercial  drug  from  a  non-injurious  impurity  contained 
only  in  small  quantity  at  the  cost  of  doubling  the  price  of  manufacture. 
Samples  A  and  B  were  obtained  from  wholesale  drug  houses  of 
first-class  repute. 
C  was  prepared  by  myself,  using  12*6  grams  of  pure  recrystallized 
oxalic  acid,  and  instead  of  17  grams  of  pure  calcic  hypophosphite  as 
the  molecular  weight  would  require  *5  gram  more  (so,as  to  insure,  if 
possible,  the  absence  of  oxalic  acid  in  the  resulting  solution),  dissolv- 
ing separately,  mixing,  filtering,  washing  and  evaporatiwg  the  fluid 
until  it  weighed  132  grams,  when  it  should  have  contained  10  per 
cent,  of  the  acid. 
