POWDER  OE  THE  TURBIT-NITROUS  MINERAL. 
395 
after  a  series  of  experiments,  in  determining  that  it  was  a 
preparation  of  mercury.  He  then  proceeded  to  ascertain  its 
true  composition,  passing  an  analytical  and  synthetical  exami- 
nation, by  which  means  more  light  was  thrown  on  the  subject. 
According  to  his  experiments,  100  grains  of  the  powder  by 
decomposition  gave  of 
Mercury,  72 
Nitric  Acid,  21 
Oxygen,  3 
Loss,  4 
100 
A  formula  was  then  published  for  its  preparation,  but  in 
1826  Dr.  J.  A.  Bernal  improved  Dr.  Jose  Estevez's  formula, 
and  published  a  dissertation  on  its  preparation  and  physical 
properties  which  were  those  of  J.  R.  Ugarte.  His  formula, 
with  some  improvements,  is  that  now  in  use,  and  is  as  follows  : 
Take  of  Mercury,  3xxx. 
Nitric  Acid,  (42°  B.)  gxviij. 
Mix  the  Mercury  and  Nitric  Acid  in  a  porcelain  capsule  and 
place  it  in  a  sand  bath,  and  apply  a  gentle  heat  until  the  dissolution 
is  effected  ;  continue  the  heat,  evaporating  until  the  mass  begins 
to  give  off  whitish  fumes  in  place  of  the  red  at  the  beginning ; 
in  this  state  remove  the  compound  from  the  heat  and  treat  it 
three  or  four  times  with  warm  distilled  water  at  70°  to  remove 
any  traces  of  the  acid,  then  dry  it  in  the  dark,  for  light  not 
only  alters  its  physical  properties,  but  acts  upon  it  chemically ; 
should  the  acid  be  less  than  42°  B,,  an  ounce  of  metallic  mer- 
cury is  to  be  diminished  for  every  degree  less  that  the  acid  con- 
tains (of  Baume.) 
Theory  of  the  Preparation  The  nitric  acid  in  contact  with 
the  metallic  mercury  is  partially  decomposed,  a  portion  of  its 
oxygen  combining  with  the  mercury  to  form  a  protoxide  of  this 
base,  and  the  part  of  the  acid  not  decomposed  combines  with  the 
oxide  formed,  giving  place  to  the  protonitrate  of  mercury;  the 
other  part  of  the  acid  set  free  from  the  oxygen,  remained  con- 
verted into  deutoxide  of  nitrogen,  which,  absorbing  the  oxygen  of 
the  atmospheric  air,  is  transformed  into  hypo-nitric  acid,  which 
is  given  off  in  the  form  of  reddish-colored  fumes.    In  these 
