358      METALLIC  COPPER  A  TEST  FOR  SULPHURIC  ACID. 
Fleitmann. 
Carbon       .       .       .    44«39  4444 
Hydrogen   .       .       .      341  342 
Nitrogen     .       .       .     2-59  2-52 
Platinum     .       .       .    18-13  1841 
These  results  prove  satisfactorily  that  Berberine  occurs  in 
X.  apiifolia,  thus  adding  another  source  for  this  very  beautiful 
alkaloid.    The  amount  present  is  not  large  ;  seven  pounds  avoir- 
dupois yielded  only  fifty-two  grains  of  the  pure  nitrate. — Lon. 
Pharm.  Jour.  May,  1862. 
METALLIC  COPPER  THE  MOST  DELICATE  TEST  FOR 
SULPHUROUS  ACID. 
By  H.  Reinsch, 
My  last  paper  on  my  test  for  arsenic*  contained  the  state- 
ment that  the  acid  liquid  obtained  by  treating  ultramarine  with 
boiling  hydrochloric  acid,  blackens  metallic  copper  ;  the  same 
result  was  had  with  a  solution  of  sulphide  of  calcium  in  muriatic 
acid.  This  reaction  I  supposed,  at  first,  to  be  produced  by  a  pe- 
culiar sulphur  compound  as  hyposulphites  and  sulphites  ought 
to  be  decomposed  by  boiling  muriatic  acid ;  but  a  long  series  of 
experiments  render  it  certain  that  it  is  due  to  sulphurous  acid. 
This  reaction  is  so  delicate  that  the  most  minute  traces  which 
cannot  be  detected  in  any  other  way,  are  thus  shown. 
If  a  few  bubbles  of  sulphurous  acid  are  conducted  into  half  an 
ounce  of  muriatic  acid,  and  two  drops  of  this  acid  are  mixed 
with  twenty  ccm.  of  water  and  ten  ccm.  of  pure  muriatic  acid,  it 
will  on  boiling  color  copper  wire  brown,  and  the  wire  has  after 
some  time  the  appearance  as  in  the  presence  of  arsenic.  In  the 
presence  of  more  sulphurous  acid,  the  wire  during  the  boiling 
appears  deep  brown-black,  and  stains  the  fingers.  Air  con. 
taining  but  traces  of  sulphurous  acid,  passed  through  muriatic 
acid,  causes  an  evident  reaction  with  metallic  copper.  To  detect 
very  minute  traces  of  sulphurous  acid,  it  is  advisable  to  make 
two  experiments,  one  with  pure  muriatic  acid,  in  which  the  cop- 
per wire  on  boiling  will  show  a  golden  lustre,  while  in  the  pres- 
*  See  page  350  of  this  Journal. 
