ON  A  NEW  COBALT  COLOR. 
157 
of  amyloxide  is  dissolved  in  6  or  8  parts  of  alcohol. — Annals  of 
Pharmacy ,  for  Feb.  8f  Dec.  1852. 
ON  A  NEW  COBALT  COLOR. 
By  M.  St.  Evie, 
Lecturer  at  the  Faculty  of  Sciences,  Besancon. 
When  a  cold  concentrated  solution  of  nitrite  of  potash  is  added 
to  a  cold  concentrated  solution  of  nitrate  of  cobalt,  a  disengage- 
ment of  binoxide  of  nitrogen  takes  place,  accompanied  by  the  de- 
position of  an  insoluble  precipitate,  of  a  peculiar  yellow  color. 
A  considerable  quantity  of  nitrate  of  potash  is  found  in  the  super- 
natant liquor. 
This  new  substance  may  also  be  produced  by  the  following 
method  :  To  the  blue  subsalt  of  cobalt,  obtained  as  a  precipitate 
by  the  addition  of  potash  to  a  solution  of  nitrate  of  cobalt,  add  a 
slight  excess  of  nitrite  of  potash,  and  allow  a  small  stream  of  ni- 
tric acid  to  flow  in  by  means  of  a  pipette;  in  this  case,  also,  a  dis- 
engagement of  binoxide  of  nitrogen  ensues,  with  the  formation  ot 
nitre,  and  the  production  of  a  yellow  precipitate. 
The  other  method  is,  first,  to  add  potash  in  slight  excess  to  a  so- 
lution of  nitrate  of  cobalt  until  the  rose  colored  protoxide  of  co- 
balt appears,  and  then  to  pass  through  the  resulting  magma  a 
current  of  binoxide  of  nitrogen. 
The  following  are  some  of  the  characteristics  and  properties  of 
this  new  body: — It  is  of  a  light  yellow  color,  answering  to  the 
yellow  in  the  chromatic  arrangement  of  M.  Chevreul.  Its  form  is 
that  of  four-sided  prisms  terminated  by  triangular  facets  ;  it  is  in- 
soluble in  water,  alcohol,  and  ether  ;  partially  soluble  in  sulphuret 
of  carbon;  neutral  to  litmus  paper.  Boiling  water  decomposes  it  out 
of  contact  of  the  air,  with  disengagement  of  binoxide  of  nitrogen; 
in  contact  of  the  air,  vapors  of  nitric  acid  are  formed  at  the  same 
time  the  solution  becomes  alkaline  and  acquires  a  rose  color,  and 
the  ordinary  nitrate  of  cobalt  and  nitrate  of  potash  are  found  in  it. 
Suspended  in  wTater,  it  resists  for  a  long  time  the  action  of  a  cur- 
rent of  chlorine,  and  it  is  only  in  heating  the  mixture  that  decom- 
position takes  place.  Under  the  same  circumstances,  it  resists 
equally  well  the  action  of  the  sulphuretted  hydrogen,  but  hydro- 
