6co       Antimonii  Oxidum  and  Pulvis  Antimonialis.  {^ovembe^fsge1' 
The  third  method  consisted  in  igniting  Sb205to  form  Sb204,  which 
is  then  weighed  and  the  per  cent,  of  Sb  calculated.  To  a  weighed 
portion  of  the  oxide  in  a  porcelain  crucible  fuming  nitric  acid  is 
added  and  carefully  driven  off  by  applying  gentle  heat ;  this  oxidizes 
the  slightly  volatile  antimonous  oxide.  The  crucible  is  then  heated 
to  redness  until  a  constant  weight  is  reached,  ioo  parts  of  Sb204 
represent  78  94  parts  of  Sb,  or  9473  parts  of  Sb203. 
Six  samples  were  examined,  using  all  three  of  the  methods  of 
estimation  upon  each  specimen.  The  first  and  third  samples  were 
made  from  a  solution  of  antimony  terchloride,  which  had  been  pre- 
pared by  the  action  of  nitro-hydrochloric  acid  upon  metallic  anti- 
mony. This  solution,  which  was  not  made  by  the  writer,  contained 
antimonic  chloride,  indicated  by  appropriate  tests ;  it  had  a  specific 
gravity  of  1-515;  the  percentage  of  antimony,  determined  by 
method  No.  1,  was  5-92,  corresponding  to  11-13  Per  cent.  SbCl3;  the 
percentage  by  method  No.  2  was  6-28,  corresponding  to  15-00  per 
cent.  SbCl5.  The  samples  of  oxide  obtained  by  the  decomposition 
of  this  solution  consisted  of  a  mixture  of  the  two  oxides,  the  varia- 
tion in  proportion  being,  doubtless,  in  the  hydration  of  the  higher 
oxide. 
The  second  sample  was  obtained  in  the  market;  but,  after  finding 
that  it  consisted  entirely  of  the  higher  oxide,  inquiry  was  made, 
which  developed  the  fact  that  it  was  stibic  acid  and  not  the  official 
oxide. 
Sample  No.  4  was  made  by  the  writer,  using  the  process  of  the 
1870  Pharmacopoeia.  It  shows  the  reliability  of  that  process  for 
manufacturing  a  U.S.P.  product. 
Sample  No.  5  was  obtained  in  the  market,  in  an  original  package 
bearing  the  label  of  a  well-known  chemical  manufacturing  firm. 
This  sample  was  also  of  good  quality. 
Sample  No.  6  was  a  commercial  article  from  another  large  manu- 
facturing house,  and  was  of  fair  quality  except  in  appearance,  which 
was  very  unfavorable. 
Samples  Nos.  4  and  5,  being  the  only  specimens  which  answered 
the  requirements  for  appearance  and  solubility,  were  further  exam- 
ined for  chlorides,  sulphates  and  metallic  impurities.  They  com- 
plied with  the  U.S.P.  requirements  in  every  particular. 
The  results  of  the  examinations  are  appended  in  tabular  form  for 
the  purpose  of  ready  comparison. 
