598       Antimonii  Oxidum  and  Pidvis  Antimonialis.  {^Vembef.'iiSI11* 
Pulvis  antimonialis,  however,  is  a  preparation  requiring  very  little 
time  or  trouble  to  make,  and  should  be  made  in  every  well-con- 
ducted establishment.  According  to  the  present  United  States  and 
British  Pharmacopoeias,  it  consists  of  33  per  cent,  of  antimonous 
oxide  and  67  per  cent,  of  calcium  phosphate.  The  original  formula, 
which  was  used  by  a  Dr.  James,  of  England,  in  the  early  part  of  the 
last  century,  was  very  crude,  and  yielded  a  preparation  of  varying 
composition  and  correspondingly  uncertain  physiological  action. 
This  method  was  adopted  by  several  of  the  earlier  European  Phar- 
macopoeias, and  consisted  in  calcining  a  mixture  of  certain  propor- 
tions of  horn  shavings  and  black  sulphide  of  antimony.  The  uncer- 
tainty of  the  composition  of  Calcaria  phosphorico-stibiata,  as  it  was 
sometimes  called,  led  to  the  adoption  of  various  processes  ensuring 
a  more  uniform  product.  One  of  these  processes  was  that  of  the 
Dublin  Pharmacopoeia  of  1850.  This  directed  that  a  solution  of 
tartar  emetic  should  be  mixed  with  a  solution  of  sodium  phosphate, 
after  which  a  solution  of  calcium  chloride  and  ammonia  water  were 
to  be  added ;  this  caused  the  precipitation  of  antimonous  oxide 
and  calcium  phosphate  intimately  mixed.  The  same  object  is 
attained  by  the  present  process,  which  consists  in  thoroughly  mix- 
ing the  precipitated  calcium  phosphate  and  antimonous  oxide. 
Several  compounds  resembling  antimonial  powder,  from  the  fact 
that  their  medicinal  efficacy  depends  upon  the  presence  of  antimo- 
nous oxide,  have  been  in  use  in  various  countries  ;  one  of  these  is 
Pulvis  resolvens,  which  is  composed  of  2  parts  of  potassium  sul- 
phate, 1  part  of  potassium  nitrate  and  1  part  of  antimonous  oxide ; 
another,  called  Tyson's  antimonial  powder,  is  a  much  milder  form. 
It  contains  2  parts  of  antimonous  oxide  and  18  parts  of  calcium 
phosphate. 
Several  oxides  of  antimony  are  known.  The  trioxide  or  anti- 
monous oxide,  Sb2Os,  exists  in  nature  principally  as  valentinite  and 
senarmontite.  It  is  prepared  artificially  by  several  methods,  which 
are  given  in  the  leading  chemical  text-books.  Its  presence  is 
established  in  a  mixture  of  the  different  oxides  by  the  black  precipi- 
tate of  argentous  oxide  which  is  produced  when  solution  of  silver 
nitrate  is  added  to  a  solution  of  the  oxide  in  potassium  hydrate ; 
the  addition  of  ammonia  water  dissolves  the  precipitate  caused  by 
the  higher  oxides  or  the  antimonates,  but  does  not  dissolve  the 
argentous  oxide. 
