.96 
Chemical  Notes, 
{Am. Jour.  Pharm. 
April,  1880. 
3.  The  general  appearance  of  the  sublimate  under  the  microscope,  even  when 
octahedral  crystals  are  present,  usually  differs  very  greatly  from  that  obtained  from 
arsenic,  the  octahedra  being  confined  to  the  lower  margin  of  the  sublimate,  and 
many  more  appearing  opaque  than  in  the  case  of  that  metal,  and  there  being  many 
granular  and  opaque  points  interspersed  among  the  crystals.  Moreover,  only  a 
single  field,  or  at  most  a  very  small  portion  of  the  sublimate  will  present  crystals,  the 
other  portions  being  either  wholly  amorphous,  or  at  most  granular. 
A-s  is  well  known,  the  arsenical  sublimate,  as  usually  obtained,  consists  wholly  of 
octahedral  crystals,  which  gradually  diminish  in  size  from  the  lower  portion  of  the 
sublimate  to  the  upper  margin,  where,  under  a  low  power  of  the  microscope,  they 
may  appear  as  mere  points  5  which,  however,  under  a  higher  power  of  the  instrument,, 
will  be  found  to  be  perfect  octahedra. 
In  a  large  series  of  experiments,  after  the  manner  in  which  this  test  is  ordinarily- 
applied  for  the  detection  of  arsenic,  we  in  no  instance  obtained  from  antimony  a 
sublimate  that  could  not  readily  be  distinguished  from  a  pure  arsenical  deposit;  yet 
it  must  be  borne  in  mind  that,  under  certain  conditions,  it  is  possible  to  obtain  from 
antimony  a  sublimate  consisting  largely,  if  not  wholly,  of  octahedral  crystals,  and 
presenting  to  the  naked  eye  the  sparkling  appearance  usually  presented  by  the 
arsenical  sublimate.  In  the  instance  already  mentioned,  in  which  large  groups  of 
prismatic  needles  were  obtained,  very  many  octahedra  were  interspersed  among  the 
prisms. 
From  the  foregoing  statements  it  is  obvious  that  the  mere  production  of  octahedral 
crystals  by  this  test  is  not,  in  itself,  conclusive  proof  of  the  presence  of  arsenic. 
When  examining  this  test  in  the  preparation  of  the  Micro-Chemistry  of  Poisons,  we 
in  a  few  instances  observed  minute  octahedra,  which  at  the  time  were  attributed  to 
the  presence  of  a  trace  of  arsenic  in  the  antimony  compound  employed.  The  entire 
absence  of  that  metal  in  the-  present  experiments  was  fully  established. 
We  also  find  that  the  deposit  of  metallic  antimony  formed  in  the  exit  tube  of  a 
Marsh  apparatus  by  decomposing  antimonuretted  hydrogen  by  heat,  may,  when, 
the  tube  is  detached  and  the  deposit  again  heated,  be  in  part  at  least  converted  into 
octahedral  crystals  of  the  oxide. 
If  pure  antimonic  oxide  be  vaporized  in  a  small  tube,  the  sublimate  usually  con- 
tains octahedral  crystals,  but  sometimes  crystalline  needles.  According  to  our 
experiments,  octahedra  are  much  more  likely  to  be  present  than  needles  ;  the  oppo- 
site result,  however,  is  stated  by  several  writers. 
Our  experience  has  confirmed  the  observation  first  made  by  Mitcherlich,  that  when, 
a  solution  of  tartar  emetic  is  decomposed  by  excess  of  ammonia,  the  precipitated 
antimonic  oxide  is  after  a  time  converted,  in  part  at  least,  into  minute  octahedra. 
CHEMICAL  NOTES. 
By  Prof.  Samuel  P.  Sadtler. 
Inorganic  Chemistry. —  On  Veshium^  a  New  Element, — A.  Scacchi 
has  communicated  to  the  Academy  of  Sciences,  of  Naples,  the  result 
of  an  investigation  of  the  green  and  yellow  incrustations  which  coat 
the  Vesuvian  lava  of  1631  in  numerous  fissures.   These  coatings  con- 
