64 
SULPHURET  OF  ANTIMONY* 
METHOD  FOR  DETECTING  SULPHURET  OF  CARBON. 
By  A.  Vogel. 
When  to  a  solution  of  caustic  potash  in  absolute  alcohol  as 
much  sulphuret  of  carbon  is  added  as  will  dissolve  therein,  a  con- 
siderable quantity  of  whitish  yellow  crystals  of  xanthate  of  pot- 
ash is  formed. 
At  the  suggestion  of  Baron  Liebig,  I  have  employed  this  pro- 
perty to  detect  small  quantities  of  sulphuret  of  carbon  in  liquids. 
If  only  a  few  drops  of  sulphuret  of  carbon  are  added  to  a  large 
quantity  of  an  alcoholic  solution  of  potash,  or  if  a  current  of 
air  is  passed  over  sulphuret  of  carbon  in  this  solution,  the  peculiar 
formation  of  crystals  does  not  ensue,  and  the  resulting  compound 
can  alone  be  detected  by  its  behavior  to  salts  of  copper.  The 
xanthate  of  potash  gives,  when  decomposed  with  acetate  or 
sulphate  of  copper,  a  voluminous  citron  yellow  precipitate. 
This  reaction  also  appears  when  only  a  small  quantity  of 
sulphuret  of  carbon  is  added  to  an  alcoholic  solution  of  potash, 
and  is  exhibited  most  distinctly  if  a  little  of  the  solution  is 
allowed  to  evaporate  on  a  watch-glass  at  ordinary  temperature, 
and  then  the  residue  treated  with  salt  of  copper.  As  the  yel- 
low precipitate  is  almost  insoluble  in  ammonia  in  the  cold,  we 
can  separate  it  from  the  oxide  of  copper  formed  at  the  same  time 
by  this  means. 
Another  property  of  the  sulphuret  of  carbon  can  also  be  em- 
ployed for  a  still  more  delicate  reaction,  when  it  is  desirable  to 
detect  this  substance.  If  an  aqueous  or  alcoholic  solution  of 
sulphuret  of  carbon  is  boiled  with  potash,  sulphuret  of  potassium 
is  formed,  which  affords  a  black  precipitate  on  the  addition  of 
nitrate  of  lead.  Yvrhen  nitrate  of  lead  is  boiled  with  potash,  and 
while  boiling,  an  extremely  diluted  solution  of  sulphuret  of  carbon 
in  water  is  added  immediately,  a  black  precipitate  results.  A  drop 
of  sulphuretted  hydrogen,  shaken  with  two  quarts  of  water,  ex- 
hibits distinctly  this  reaction,  which  is  still  applicable,  therefore, 
in  cases  of  extraordinary  dilution. 
It  has  been  correctly  assumed,  that  sulphuret  of  carbon  is 
always  contained  in  coal  gas,  because  the  conditions  for  its  forma- 
tion in  the  manufacture  of  gas  from  coal,  which  always  con- 
tains  sulphur,  are   in  existence.    No   research   is,  however, 
