314 
CHLORIDE  OF  POTASSIUM  FROM  CARNALLITE. 
by  heating  in  a  glass  retort  a  mixture  of  10  parts  sulphur  with. 
24  p.  anhydrous  proto-sulphate  of  iron.  The  gas  is  very  pure  ; 
a  little  sulphur  is  readily  separated  by  passing  it  through  loose 
cotton,  and  the  residue  is  useful  for  generating  sulphuretted  hy- 
drogen ;  other  metallic  sulphates  may  be  used  in  the  same  way. 
(Ph.  Cent.  Halle,  1866,  N.  52). 
Paraguay  tea.  D.  A.  Strauch  has  again  analyzed  these 
leaves,  with  the  following  results  :  theina  '450,  volatile  oil  a  trace, 
caffeotannic  acid  20-880,  gum  2*830,  resin,  chlorophyll  and  wax 
5-902,  starch  1-200,  protein  compounds  9-361,  cellulose  22-148, 
apotheme  8-640,  salts  3-896,  water  8*100,  sand  and  extractive. 
(Wittst.  Viertelj.,  1867,  16T— 182). 
on  the  preparation  of  chloride  op  potassium 
from  the  carnallite  of  stassfurth,  Prussia. 
By  M.  Stromeyer. 
It  is  well  known  that  the  pure  rock  salt  is  covered  in  that 
neighborhood  by  a  large  bed  of  impure  salt  ("refuse  "  salt),  in 
which  are  contained,  besides  many  other  interesting  minerals, 
two  substances  in  considerable  amount,  which  are  useful  in  the 
arts — kieserite,  a  sulphate  of  magnesia  with  one  atom  of  water, 
and  carnallite,  a  hydrated  double  salt  of  chloride  of  magnesium 
and  chloride  of  potassium  (K  CI  +  2Mg  CI  +  12  HO).  These 
two  chlorides  are  united  by  so  weak  an  affinity  as  to  be  readily 
separated  by  dissolving  them  in  hot  water,  when,  on  cooling,  the 
chloride  of  potassium  crystallizes  out,  and  the  chloride  of  mag- 
nesium remains  in  solution.    When,  also,  the  double  salt  is 
drenched  with  a  little  cold  water,  or  is  exposed  to  moist  air,  the 
chloride  of  magnesium  is  dissolved  out,  and  the  chloride  of  po- 
tassium left  behind.    This  double  salt,  which  had  been  found  by 
Liebig  some  time  ago  in  the  mother  liquor  of  a  certain  saline, 
affords  a  very  convenient  material  for  the  preparation  of  chloride 
of  potassium.    Chloride  potassium  has  for  some  time  been  used 
in  the  conversion  of  the  nitrate  of  soda  from  Peru  into  saltpetre, 
and  for  the  manufacture  of  potash  alum.    It  was  obtained  from 
the  ashes  of  kelp,  particularly  at  Cherbourg,  in  France,  and  at 
Glasgow,  Scotland,  and  in  large  quantities  at  the  sea-salt  salines 
