DETECTION  OP  PHOSPHORUS  IN  CASES  OF  POISONING.  127 
remained  long  enough  in  the  body  before  death  occurred,  to  become 
oxidized  into  phosphorous  acid ;  this  may  even  be  possible  in  a 
corpse  which  has  been  interred  for  some  time. 
The  substance  is,  if  necessary,  rendered  sufficiently  liquid  with 
water,  and  without  the  addition  of  an  acid  is  distilled  from  a  flask 
connected  with  Mitscherlich's  apparatus.  The  most  minute 
quantity  of  free  phosphorus  will  evidence  itself  by  the  peculiar 
vapors  and  the  characteristic  luraination  in  the  dark.  If  this  is  not 
observed,  and  there  exists  the  suspicion  of  poisoning  by  phos- 
phorus, the  reaction  of  the  liquid  to  litmus  is  observed.  In  case 
of  an  alkaline,  neutral  or  very  slight  acid  reaction,  no  further 
investigation  for  phosphorus  is  advisable. 
In  case  of  a  strong  acid  reaction,  the  substance  is  mixed  with 
an  equal  volume  of  alcohol,  which  coagulates  albuminous  bodies 
and  dissolves  but  little  fat.  After  a  short  time  it  is  filtered,  the 
residue  washed  with  weak  alcohol,  and  the  filtrate  evaporated  to 
a  syrupy  consistence^,  when  it  is  to  be  mixed  with  at  least  three 
times  its  volume  of  absolute  alcohol.  The  filtrate  is  evaporated 
and  the  operation  repeated  twice. 
The  residue  when  dissolved  in  water  is  neither  precipitated  by 
ammonia  nor  oxalate  of  potassa,  even  though  phosphate  of  lime 
had  been  intentionally  added  at  the  beginning  ;  it  is  well  to  be- 
come satisfied  of  the  absence  of  these  reactions.  To  one  half  of 
the  solution,  some  zinc  and  dilute  sulphuric  acid  is  added,  and  the 
gas  conducted  into  a  solution  of  silver,  from  which  a  reduction  of 
silver  by  phosphuretted  hydrogen  will  take  place,  if  phosphor- 
ous acid  had  been  present.  The  gas  will  burn  with  a  greenish 
flame,  as  was  observed  by  Duflos,  without  producing  a  deposit 
upon  porcelain. 
The  other  half  is  mixed  with  a  few  drops  of  nitric  acid,  neu- 
tralized with  pure  carbonate  of  soda,  evaporated  and  heated  to 
redness  to  destroy  fatty  acids,  then  dissolved  in  water,  neutral- 
ized and  tested  for  phosphoric  acid,  when  it  must  not  be  left  out 
of  view  that  possibly  only  pyrophosphoric  acid  may  be  present. 
It  is  not  advisable  to  test  before  the  evaporation  for  phosphor- 
ous acid,  because  similar  reactions  may  occur  with  the  fatty 
acids. 
The  above  experiments  control  one  another  ;  if  all  the  reac- 
tions take  place,  we  may  conclude  on  the  poisoning  by  phosphorus. 
{Arch,  d.  Pharm.  cli.  138 — 141.)  J.  M.  M. 
