234 
ON  FUSED  CYANIDE  OF  POTASSIUM. 
easily  done,  as  the  mass  is  always  soft.  Or  the  extract,  treated 
with  carbonate  of  potash,  may  be  taken  out  of  the  dish  and 
formed  into  thin  cakes,  which  are  brought  to  complete  dryness 
on  a  furnace.  In  this  way  a  blackish  mass  of  resinous  appear- 
ance is  obtained  ;  it  possesses  the  odor  of  tea,  and  is  easily  pow- 
dered. The  powder  is  passed  through  a  hair-sieve  and  put  into 
a  flask  with  a  ground  stopper ;  alcohol  is  then  poured  into  it,  the 
flask  is  closed,  kept  in  a  warm  place,  and  shaken  from  time  to 
time,  the  alcohol  being  changed  until  it  no  longer  exerts  any 
action  upon  the  extract.  The  alcoholic  extracts  are  mixed  to- 
gether and  distilled,  and  the  fluid  remaining  in  the  retort  is  taken 
out  and  evaporated  in  a  porcelain  dish  until  it  furnishes  crystals 
on  cooling.  These  are  pressed  between  thick  linen,  dissolved 
again  in  well-water,  and  thus  furnish  a  sufficiently  pure  thein, 
which  may  be  obtained  very  white  by  treatment  with  animal 
charcoal. 
The  author  has  employed  this  process  with  both  green  and 
black  tea.  The  green  tea  furnished  only  about  half  as  much 
cafFein  as  the  black,  which  confirms  the  observations  of  Liebig 
and  others.  By  the  most  careful  treatment  of  different  kinds  of 
black  tea,  he  obtained  very  variable  quantities  of  the  product, 
depending,  of  course,  upon  the  differences  in  the  quality  of  the 
tea.    The  following  are  his  numerical  results : 
Tea  employed.                                    Thein  obtained.  Per  cent. 
4608  grins,  green  tea                      38  grms.  0*82 
3456  grms.  common  black  tea           40  grms.  1*16 
3312  grms.  the  same,  another  kind    30  grms.  0  90 
1584  grms.  congou  tea                     40  grms.  2-55 
London  Chem.  Gfaz.,  Feb.  1,  1856,  from  Arohiv.  der  Pharm. 
ON  FUSED  CYANIDE  OF  POTASSIUM. 
By  Dr.  Wjttstein. 
Preparation. — Eight  parts  of  yellow  prussiate  of  potash  are 
finely  powdered,  thoroughly  dried  with  a  gentle  heat,  intimately 
mixed  with  three  parts  of  pure  carbonate  of  potash,  the  mixture, 
thrown  by  spoonfuls  into  a  red  hot  Hessian  or  iron  crucible, 
allowed  to  remain  in  the  fire  until  thoroughly  fluid,  and  a  glass 
rod  or  iron  spatula  dipped  into  it  and  withdrawn,  becomes 
