ON  LITHIUM  AND   STRONTIUM.  359 
at  the  bottom  of  which  a  filter  is  formed,  composed  of  successive 
layers  of  quartz-stone  finely  powdered,  and  the  grain  of  which 
decreases  in  size  from  bottom  to  top.  After  the  iodine  has  been 
sufficiently  drained,  it  is  drawn  off  without  disturbing  the  lower 
layer  of  iodine,  and  conveyed  to  a  rectangular  box,  made  of 
plaster  of  Paris,  closed  by  means  of  a  lid  of  the  same  composi- 
tion, sliding  friction-wise  in  two  parallel  grooves.  The  lid  of  the 
box  should  be  thick  enough  (but  not  too  compact)  to  allow  the 
water  of  imbibition  to  filter  into  the  sides  and  lid  of  the  box. 
"When  the  iodine  is  sufficiently  dried,  it  is  crystallized  by  subli- 
mation. 
To  extract  iodine  from  the  mother-liquor  in  the  state  of  iodate 
and  iodide,  the  liquors  are  treated  successively  with  a  solution  of 
chlorine  and  sulphurous  acid,  previously  tested  in  the  following 
manner  : — When  the  liquor  contains  little  iodide  and  much  iodate, 
the  iodine  contained  in  the  iodide  is  first  precipitated  by  means 
of  chlorine  ;  and  as  soon  as  the  reaction  is  terminated,  a  sufficient 
quantity  of  solution  of  sulphurous  acid  for  decomposing  the 
iodates  is  added.  If  the  mother-liquor  contains  much  iodide  and 
little  iodate,  a  solution  of  sulphurous  acid  is  first  employed,  and 
afterwards  an  aqueous  solution  of  previously  tested  chlorine. 
Several  cubic  feet  of  the  mother-liquors  may  be  treated  at  a  time 
with  precision  and  facility. 
The  above  processes  are  economical  and  expeditious,  and  have 
the  advantage  of  avoiding  the  loss  of  nitrate  of  potash  or  soda 
during  the  concentration  of  the  liquors,  which  result  cannot  be 
effected  by  the  employment  of  sulphuric  acid  of  commerce  by 
the  ordinary  method. — Dated  Feb.  14,1854. —  Chem.  6rtf2.,  May 
15,  1855. 
ON  LITHIUM  AND  STRONTIUM. 
By  M.  Bunsen. 
(Extract  of  a  Letter  to  M.  Regiiaitlt.) 
I  send  you  a  small  specimen  of  lithium,  which  I  have  prepared 
in  concert  with  Mr.  Mathiessen  by  electrolysis.  It  forms  a  Wire 
of  several  decimetres  in  length,  and  about  three-fourths  of  a 
millimetre  in  diameter. 
Lithium  has  the  color  and  brilliancy  of  silver,  from  which  it 
