232 
ON  A  NEW  METHOD  OF  PREPARING  CAFFEIN. 
residue.  This  is  effected  most  conveniently  in  a  glass  percolator 
of  conical  shape,  the  smaller  end  of  which  is  closed  with  a  piece 
of  thick  linen.  The  percolator  is  fitted  with  a  cork  into  the 
neck  of  a  bottle,  the  extract  placed  in  it  and  treated  with  ether, 
which  will  yield  a  yellowish  tincture.  The  wider  upper  end  of 
the  glass  tube  is  loosely  closed  with  a  cork.  The  scales,  after 
evaporation  of  the  ether,  are  treated  with  cold  alcohol  of  80  per 
cent,  for  one  day,  frequently  shaking  ;  the  alcohol  is  then  poured 
off,  the  laminas  spread  on  blotting  paper  and  dried  in  the  air. 
One  pound  of  Spanish  flies  yields  from  20  to  30  grains  of  can- 
tharidin. 
Cantharadin  *may  also  be  prepared  by  direct  treatment  of 
the  Spanish  flies  with  ether  or  alcohol,  but  I  cannot  recommend 
the  method,  as  by  it  a  quantity  of  fatty  oil  is  extracted,,  the  sub- 
sequent separation  of  which  is  difficult,  and  occasions  a  loss  of 
cantharidin. 
Recapitulation. — Cantharidin  exists  in  the  insect  in  an  un« 
combined  state  ;  and  owing  to  the  extractive  matter  present,  is 
taken  up  by  water,  in  which  menstruum,  when  pure,  It  is  inso- 
luble. To  dry  the  watery  extract  readily,  and  obtain  it  in  a  fit 
state  for  exhaustion  with  alcohol,  the  charcoal  is  used.  The 
ethereal  extract  will  yield  with  alcohol  a  yellow  (resinous)  matter* 
Properties  Pure  cantharidin  forms  white,  glittering,  odor- 
less and  tasteless  scales.  In  water  it  is  insoluble,  and  nearly  so 
in  cold  alcohol,  but  readily  in  boiling  alcohol  ;  ether  and  fatty 
oils  readily  dissolve  it  in  the  cold.  Heated,  it  melts  and  vola- 
tilizes in  white  vapors,  which  possess  in  a  marked  degree  the 
stupifying  odor  of  Spanish  flies,  and  condense  on  cold  substances* 
Prac.  PItarm.  Chem. 
NEW  METHOD  OE  PREPARING  CAFFEIN. 
By  M.  Puccetti. 
The  modes  of  preparing  caffein  hitherto  employed  may  be 
reduced,  with  slight  modifications,  to  the  action  of  acetate  and 
oxide  of  lead  upon  the  decoction  of  finely-powdered  unroasted 
coffee.  This  fluid  thus  obtained,  from  which  the  caffein  is  al- 
lowed to  crystallize,  always  contains  a  very  large  quantity  of 
extractive  matter,  which,  as  it  is  very  soluble  in  alcohol  and 
