FORMATION    OF  SULPHOCYANURET  OF  POTASSIUM.  3(J3 
tract  is  evenly  spread,  then  the  thermometer  is  placed  somewhat 
near,  so  that  its  bulb  reaches  nearly  to  the  middle  of  the  appa- 
ratus, and  half-an-inch  from  the  bottom.  The  dish  is  covered 
with  an  ordinary  piece  of  gauze,  and  then  with  a  paper  hat, 
about  15  inches  high.  The  apparatus  is  placed  on  a  sheet  of 
iron,  which  is  strewed  with  half-an-inch  of  dry  sand,  and  this  is 
set  on  a  furnace. 
A  tolerably  strong  fire  is  kept  up,  until  the  thermometer  rises 
to  about  295°  Fahr.,  upon  which  the  heat  must  be  quickly  mode- 
rated. The  thermometer  soon  raises  to  about  390°,  and  the 
acid  rapidly  sublimes.  The  latter  temperature  is  maintained  for 
three  hours ;  and  after  this  time  a  considerable  quantity  of  co- 
lorless pyrogallic  acid  is  found  in  the  hat.  By  this  method  50 
pounds  of  Chinese  galls  will  yield  2  pounds  of  pyrogallic  acid. 
— Annals  of  Pliarm.  from  Journal  fur  Praktische  Chemie. 
THE  FORMATION  OF  SULPHOCYANURET  OF  POTASSIUM  IN  THE 
WET  WAY. 
By  Dr.  Lowe. 
When  a  watery  solution  of  a  weighed  quantity  of  ferrocyanu- 
ret  of  potassium  is  mixed  with  sulphuret  of  potassium  in  the 
usual  proportions,  or  with  sulphur  and  carbonate  of  potash,  and 
the  mixture  heated  to  boiling,  the  solution,  after  a  few  minutes, 
becomes  greenish,  under  the  separation  of  sulphuret  of  iron,  the 
quantity  of  which  increases  according  to  the  length  of  the  boil- 
ing of  the  liquid.  After  long-continued  boiling,  all  the  ferro- 
cyanuret  of  potassium  is  completely  replaced  by  the  sulphocy- 
anuret  of  potassium.  If  the  suspended  sulphuret  of  iron  is  now 
separated  by  filtration  from  the  fluid,  the  latter  allowed,  in  case 
it  should  be  still  colored  yellow,  to  stand  in  the  air  a  short  time 
until  it  is  colorless,  the  whole  evaporated  to  dryness  in  a  water- 
bath,  and  the  residue  extracted  with  alcohol,  a  tolerably  satu- 
rated alcoholic  solution  of  sulphocyanuret  of  potassium  is  thus  ob- 
tained. The  residue  insoluble  in  alcohol  contains  very  small 
quantities  of  ferrocyanuret  of  potassium,  whose  decomposition 
and  conversion  should  be  effected  by  further  boiling.  A  solu- 
tion of  ferrocyanuret  of  potassium,  boiled  with  sulphur  alone, 
is  converted  into  sulphocyanuret  of  potassium,  under  the  simul- 
