ACIDUM  PHOSPHORICUM  DILUTUM. 
359 
But  red  phosphorus  had  been  proved  to  be  destitute  of  poison- 
ous action,  and  this  innocuity  had  been  ascribed  to  its  non-oxy- 
dation. 
This  latter  assumption  being  now  proved  to  be  incorrect,  "  it 
is  important  to  solve  the  question  by  direct  experiments,  that 
can  leave  not  the  least  doubt  of  the  poisonous  action  or  innocuity 
of  phosphorous  acid.  For  this  purpose  I  have  given  to  dogs 
quantities  of  phosphorous  acid,  varying  from  0.6  grm.  to  1.45 
grm.  of  the  supposed  anhydrous  acid.  Six  dogs  have  been  em- 
ployed in  these  trials ;  in  all  the  dogs,  the  oesophagus  has  been 
tied  after  the  injection  of  the  diluted  acid  into  the  stomach,  and, 
to  my  great  astonishment,  these  animals  have  all  of  them  lived 
six,  eight,  or  even  nine  days  after  the  injection  of  the  pretended 
poison.  I  will  add,  that  for  each  of  these  six  experiments,  I 
have  employed  a  phosphorous  acid  proceeding  from  a  special 
operation,  and  the  quantities  of  acid  have  been,  for  greater- 
exactitude,  tested  by  means  of  the  transformation  of  the  per- 
chloride  of  mercury  into  protochloride,  according  to  the  following 
aequation : 
PCX  +  4  Hg  CI  +  2  HO  =  P05  +  2  (Hg20l)  +  2  H  CI. 
"  The  acid  that  has  served  for  these  experiments  has  always 
been  obtained  by  the  decomposition  of  protochloride  of  phospho- 
rus by  water,  and  the  evaporation  of  the  acid  liquor  over  lime  in 
an  exhausted  receiver." 
The  eventual  death  of  the  dogs  is  accounted  for  by  «  then- 
prolonged  abstinence,"  and  »  the  results  of  the  injuries  conse- 
quent on  tying  their  oesophagus." 
The  point  I  mainly  wish  to  insist  on,  is  the  great  advantage 
of  adopting  M.  Personne's  suggestion,  that  red  phosphorus,  in 
fine  division,  is,  from  the  readiness  with  which  it  is  attacked  by 
dilute  nitric  acid,  exceedingly  well  adapted  for  the  preparation 
of  tribasic  phosphoric  acid. 
I  have  always  been  annoyed  by  the  tediousness  of  the  P.  L. 
process,  and  have  sometimes  been  unfortunate  in  either  breaking 
apparatus  or  burning  my  fingers ;  and  not  having  been  able 
hitherto  to  devise  a  better  process,  I  gladly  adopted  the  idea  of 
M.  Personne,  and  attempted  its  preparation,  using  the  exact 
quantities  prescribed  in  the  London  Pharmacopoeia. 
