3 1 6  Gleanings  from  the  Foreign  Journals.  { Am ){Z%i^m' 
Change  of  Cantharidin  in  Cantharides. — R.  Wolff,  of  Buenos 
Ayres,  used  for  his  experiments  Lytta  aspersa,  which  is  there  generally 
employed.  On  treating  100  grms.  with  ether,  '815  grm.  cantharidin 
was  obtained,  besides  some  fixed  oil  which,  after  saponification,  yielded 
-04  grm.  more  of  that  principle.  The  lytta,  exhausted  with  ether, 
was  now  extracted  with  warm  water,  the  liquid  evaporated  to  a  syrupy 
consistence  and  precipitated  with  barium  chloride.  The  washed  brown 
precipitate  was  mixed  with  an  excess  of  hydrochloric  acid,  evaporated 
to  dryness  and  the  residue  exhausted  with  chloroform,  which  on  evap- 
oration and  washing  with  ether  left  "46  grm.  of  white  tabular  crystals 
which  possess  vesicating  properties,  are  soluble  in  water,  more  in 
alcohol  and  ether,  and  rather  freely  in  chloroform  and  acetic  ether. 
On  evaporating  the  latter  solution,  cantharidin  is  left.  It  is  soluble  in 
sulphuric  acid,  and  on  the  addition  of  water  cantharidin  is  precipitated, 
sulphate  of  ammonium  remaining  in  solution.  From  its  solution  in 
potassa,  it  is  separated  in  an  unaltered  condition  on  neutralization  with 
an  acid.  Boiling  with  ammonia  and  evaporation  to  dryness  causes  this 
cantharidin  ammonia  compound  to  combine  with  more  ammonia. 
This  second  compound  crystallizes  from  hot  water  in  needles  ;  it  is 
also  vesicating,  but  is  slightly  soluble  even  in  hot  alcohol,  ether  and 
chloroform  ;  but  dissolves  in  acetic  ether  which,  on  evaporation,  leaves 
•cantharidin.  It  dissolves  in  sulphuric  acid,  from  which  solution  no 
precipitation  is  effected  by  water.  Acids  seem  to  combine  with  it,  for 
when  its  solution  in  muriatic  acid  is  evaporated  to  dryness,  the  residue 
is  freely  soluble  in  hot  water  and  precipitated  by  silver  nitrate,  the  pre- 
cipitate being  insoluble  in  nitric  acid.  Heated  with  potassa,  it  is  partly 
decomposed  into  the  first  described  ammonia  compound. 
If  cantharidin  is  dissolved  in  potassa,  the  solution  precipitated  by  a 
salt  of  zinc  (or  copper,  or  magnesia),  the  precipitate  redissolved  in 
ammonia,  and  the  solution  supersaturated  with  an  acid,  the  first-described 
ammonia  compound  is  separated  in  crystalline  granules.  A  similar 
•reaction  takes  place,  probably,  in  cantharides  ;  they  contain  magnesium 
•salts,  and  when  ammonia  is  generated  in  them  through  the  agency  of 
moisture,  the  conditions  for  the  formation  of  that  compound  are  pre- 
sent. The  above  results  explain  also  why  larger  yields  of  cantharidin 
are  obtained  by  treatment  with  acetic  ether. 
The  author  argues  in  favor  of  preparations  of  cantharidin  in  place 
of  the  deteriorating  and  therefore  unreliable  cantharides. — Archiv  d. 
Phar.,  Jan.,  1877,  p.  22-30. 
