414  The  Adminiftration  of  Phosphorus.  {^"^•^llT^ln''^' 
taining  oxygen  products  of  arsenic  and  phosphorus.  This  preparation 
is,  in  his  opinion,  unworthy  of  any  attention. 
Phosphide  of  zinc,  Dr.  Mehu  thinks,  cannot  be  considered  as  a  me- 
dicament presenting  free  phosphorus  to  the  system. 
Dr.  Mehu  shares  the  opinion  of"  Mr.  Martindale,J  that  the  previous 
heating  of  oil  of  almonds  to  300°  F.  is  not  a  precaution  absolutely 
necessary  in  the  preparation  of  phosphorated  oil  of  good  quality  ;  but 
he  adds  that  his  recommendation  of  this  preliminary  heating  had  for  its 
object  the  rendering  of  the  preparation  unalterable  by  light.  That  it 
has  this  effect  he  has  proved  by  the  preservation  of  flasks  of  oil  con- 
taining I  per  cent,  of  phosphorus,  exposed  to  the  light  during  seven 
years,  without  manifesting  the  slightest  turbidity  or  depositing  a  trace 
of  red  phosphorus.  At  the  Pharmaceutical  Congress  in  St.  Petersburg 
he  exhibited,  for  comparison,  phosphorated  oil  unaltered  which  had 
been  prepared  six  years  with  previously-heated  oil  of  almonds,  and 
some  prepared  with  the  same  kind  of  oil  not  previously  heated.  The 
phosphorus  in  the  latter  was  almost  entirely  precipitated  in  the  state  of 
red  phosphorus,  although  the  solution,  like  the  former,  had  been  kept 
in  a  vessel  sealed  at  the  lamp. 
Mr.  Ashburton  Thompson  stated*  that  the  phosphorated  oil  is  an 
unsatisfactory  preparation,  because  when  exposed  to  the  air  the  phos- 
phorus which  it  contains  readily  oxidizes.  Dr.  Mehu  points  out  that 
this  oxidation,  which  is  common  to  all  preparations  containing  free 
phosphorus,  may  be  prevented  by  the  addition  of  a  few  drops  of  ether. 
The  same  result  may  be  attained  by  the  use  of  a  small  quantity  of  oil 
of  turpentine,  but  such  an  addition  may  be  objectionable,  since  oil  of 
turpentine  acts  as  an  antidote  to  phosphorus.  Dr.  Mehu  states  that  he 
has  kept  phosphorated  oil  to  which  a  very  small  quantity  of  ether  has 
been  added,  for  months,  in  bottles  opened  every  day,  without  the  oil 
undergoing  any  sensible  alteration. 
Dr.  Mehu  supplements  his  criticisms  by  some  details  as  to  what  he 
has  found  to  be  the  best  mode  of  preparing  phosphorated  oil.  Pure 
oil  of  sweet  almonds,  slightly  colored,  limpid,  free  from  admixture 
with  oil  from  plum  and  peach  kernels,  sometimes  present  in  commer- 
cial oil,  is  the  oil  he  prefers  to  use.  This  oil  is  heated  in  a  porcelain 
capsule.  At  a  temperature  near  150°  C.  it  is  very  perceptibly  decolor- 
ized, and  this  decoloration  is  more  marked  as  the  temperature  rises,  but 
X  "  Pharm.  Journ."  [3],  vol.  iv,  p.  902. 
*"Pharm.  Journ."  [3],  vol.  iv,  p.  965. 
