A.m.  Jour.  Pharrr. 
April,  1880. 
Tests  for  Arsenic. 
195 
iublimate  differs  widely  from  that  produced  from  arsenic.  We  quote 
from  Prof.  Wormley's  paper  as  follows  : 
The  statements  in  regard  to  the  behavior  of  the  antimony  deposit,  however,  have 
been  somewhat  discordant.  Thus,  by  some  writers,  it  is  stated  that  this  metal  fails 
to  yield  any  sublimate  whatever 5  by  others,  that  it  yields  an  amorphous  sublimate; 
and  by  others  still,  that  the  deposit  is  either  amorphous  or  granular.  According  to 
Professor  W.  A.  Miller,  however,  the  antimony  deposit,  when  heated,  "gradually 
'becomes  oxidized,  and  at  a  higher  temperature  the  oxide  is  volatilized,  condensing 
in  needles  ;  not,  like  arsenic,  in  octahedra."    "  Elements  of  Chemistry,'"  ii,  p.  602. 
This  statement  of  Professor  Miller  was  strongly  urged  a  few  years  since  in  a 
•somewhat  noted  trial  as  evidence  of  the  absence  of  antimony,  since  on  the  application 
of  the  copper  test  there  was  a  failure  to  obtain  crystalline  needles.  Immediately 
after  this  trial,  in  1872,  we  very  carefully  examined  this  test  in  regard  to  the  character 
of  the  sublimate  produced  by  antimony.  In  over  fifty  consecutive  experiments  of 
this  kind,  in  which  copper,  pretty  heavily  coated  with  antimony,  but  used  in  small 
portions  at  a  time,  was  employed,  we  failed  to  obtain  well-defined  crystalline 
needles,  except  in  some  three  or  four  instances  in  which  a  few  needles  were  observed, 
and  in  one  in  which  the  sublimate  consisted  largely  of  large  groups  of  prismatic 
needles  with  single  prisms. 
But,  what  is  of  more  importance  in  a  forensic  point  of  view,  we  found  that  the 
sublimate  produced  from  antimony  might  contain  octahedral  crystals  of  antimonic 
oxide,  and  that  under  certain  conditions  it  was  almost  sure  to  contain  such  crystals. 
In  a  number  of  instances  sublimates  were  obtained,  which,  when  examined  under 
ihe  microscope,  presented  fields  which,  taken  alone,  could  not  be  distinguished  from 
an  arsenical  sublimate  by  the  most  experienced  eye. 
These  octahedral  crystals  are  more  likely  to  form  when  the  heat  is  applied  very 
gradually,  and  especially  when  the  reduction-tube  is  relatively  large  to  the  quantity 
of  deposit  submitted  to  sublimation.  In  no  instances  were  octahedral  crystals  obtained 
when  a  very  narrow  or  contracted  tube  was  employed.  It  would  thus  appear  that 
for  the  production  of  crystals,  antimony  required  a  more  free  supply  of  air  than 
arsenic,  although  the  absolute  quantity  of  oxygen  required  is  less. 
Although  it  is  thus  possible  to  obtain  from  antimony  sublimates,  certain  portions 
of  which,  under  the  microscope,  are  not  to  be  distinguished  from  the  results  obtained 
from  arsenic,  yet  there  is  considerable  difference  in  the  general  behavior  of  these 
metals  under  the  action  of  this  test. 
1.  The  antimony  deposit  requires  a  much  higher  temperature  to  volatilize  it, 
vaporizing  at  little,  if  any,  below  a  dull  red  heat ;  whereas,  according  to  recent 
investigations,  metallic  arsenic  volatilizes  at  about  356°F.,  or,  according  to  Professor 
•Guy,  even  so  low,  when  in  small  quantity,  as  23o°F. 
2.  The  position  of  the  sublimate  in  the  reduction-tube,  as  usually  obtained,  may 
serve  at  once  to  distinguish  the  antimonial  from  the  arsenical  deposit.  In  the  case 
of  antimony,  on  account  of  its  less  volatility,  the  lower  margin  of  the  sublimate  (in 
which  the  crystals,  when  present,  are  found)  is  only  slightly  in  advance  of  the  slip 
of  copper,  or  the  sublimate  may  even  form  on  the  sides  of  the  tube  surrounding  the 
copper,  especially  when  the  heat  is  restricted  to  the  lower  end  of  the  tube;  whilst, 
as  is  well  known,  in  the  case  of  arsenic  the  sublimate  usually  forms  half  an  inch  or 
more  in  advance  of  the  copper  foil. 
