1 8  2  Sulphocarbonate  of  Potassium .        { ^Xxs^™ " 
If  a  watery  solution  of  caustic  potassa  is  agitated  with  carbon  bisul- 
phide, the  latter  is  gradually  dissolved,  yielding  a  brown  liquid,  which, 
contains  both  carbonate  and  sulphocarbonate  of  potassium  in  solution  \. 
6KHO+3QS2  yields  K2C03+2K2CS3+3H20.  Both  newly  formed 
compounds  have  a  similar  behavior  to  water  and  alcohol,  and  therefore 
cannot  be  separated  either  by  crystallization  or  bv  precipitation  with, 
alcohol,  and  since  the  application  of  strong  solutions  of  alkaline  car- 
bonates is  inadmissable,  the  process  described  cannot  be  advantageously 
used  for  the  preparation  of  potassium  sulphocarbonate.  Such  a  solu- 
tion will  effervesce  briskly  on  the  addition  of  diluted  hydrochloric  or 
sulphuric  acid,  and  after  the  neutralization  of  the  liquid  the  further 
addition  of  acid  will  render  the  mixture  milky  from  the  separation  of 
sulphocarbonic  acid,  H2CS3,  which  gradually  forms  a  heavy  red-brown> 
oil,  capable  of  decomposing  the  carbonates  with  the  evolution  of  car- 
bonic acid  gas. 
On  treating  an  alcoholic  solution  of  caustic  potassa  with  carbon  bisul- 
phide, the  reaction  is  very  different  from  the  preceding,  and  results  in 
the  production  of  sulphcarbovinate  of  potassium  ;  KHO +  C2H60 -f-CS2, 
yields  KC2H5OCS24-H20.  This  salt  gives  with  a  solution  of  sulphate 
of  copper  a  yellow  precipitate,  and  the  acid  contained  in  it  has  also- 
been  known  as  xanthome,  xanthic  and  xanthogenic  acid;  it  was  discovered 
by  Zeise  in  1822. 
By  substituting  in  the  above  processes  caustic  soda  or  lime  for  the 
potassa,  corresponding  sodium  and  calcium  compounds  are  obtained. 
The  soluble  sulphocarbonates  yield  brown  precipitates  with  salts  oi. 
copper,  red  ones  with  salts  of  lead,  and  yellow  ones  with  mercuric,, 
cadmium  and  silver  salts.  Many  of  these  compounds  with  the  heavy 
metals  are  gradually  turned  black. 
According  to  Delachanal  (1877)  the  solutions  of  potassium  sulpho- 
carbonates of 
Degrees  Baume 
10 
20 
30 
40 
50 
have  the  the  density 
1:075 
11  61 
1-262 
1383 
1-530; 
and  contain  per  cent. 
K2CS3 
107 
22' 
35* 
4-8-9 
63-7 
H              «(  (t 
cs2 
4*37 
8-98 
14-28 
!9'95 
25-99, 
