Amjiner*i879a.rm }       Valuation  of  Blistering  Beetles.  297 
powder  were  now  exhausted  with  acetic  ether  by  displacement,  about  six 
fluidounces  of  percolate  being  obtained.  The  greater  part  of  the  acetic 
ether  was  distilled  off  and  the  balance  allowed  to  evaporate  spontane- 
ously. The  residue  was  treated  with  bisulphide  of  carbon,  which  dis- 
solved a  portion  of  the  fatty  matter,  but  a  considerable  quantity 
remained  undissolved,  as  in  the  former  case.  The  residue  was  dis- 
solved in  hot  alcohol,  from  which,  on  cooling,  1*3  grain  of  much 
purer  cantharidin  crystallized,  while  that  remaining  in  the  alcohol  could 
not  be  freed  by  simple  solvents  from  the  contaminating  foreign  matter. 
200  grains  of  the  powder  were,  according  to  Dragendorff's  process, 
digested  in  hydrate  of  potassium  for  about  fifteen  minutes,  the  mixture 
treated  with  hydrochloric  acid  in  excess,  dried  and  treated  by  displace- 
ment with  petroleum  benzin,  with  the  view  of  removing,  if  possible, 
the  fatty  matter  beforehand.  A  dark-colored  solution  was  obtained, 
from  a  portion  of  which  the  benzin  was  evaporated  off,  leaving  the  oil 
of  a  dark-brown  color  and  of  a  butyraceous  consistence.  This  was 
tested  for  cantharidin  by  applying  a  small  quantity  to  the  arm,  but  no 
effect  was  produced,  proving  the  insolubility  of  cantharidin  in  petroleum 
benzin.  The  powder  was  then  exhausted  with  chloroform  and  treated 
in  the  same  manner  as  in  the  first  experiment.  The  cantharidin 
obtained  by  this  process  was  of  a  much  purer  form,  crystalline  and  of 
a  light-yellow  color,  and  weighed  2  5  grains. 
The  yield  and  purity  of  the  product  being  most  satisfactory  by  this 
last  process,  it  was  adopted  in  the  following  experiments  : 
Cantharis  vittata,  the  potato  bug,  was  next  examined,  150  grains  of 
the  powder  being  used,  yielding  two  grains  of  almost  pure  cantharidin 
in  rather  large  crystals,  which,  when  obtained,  along  with  the  fatty 
matter,  were  long  and  needle-shaped,  but  after  purification  assumed  a 
square  and  tabular  form.  This  leads  to  the  conclusion  that  the  presence 
of  the  fatty  matter  changed  the  shape  of  the  crystals. 
Three  specimens,  200  grains  each  of  Cantharis  vesicatoria,  were  next 
examined.  The  first  was  a  sample  of  the  fresh,  two  of  old  beetles, 
one  consisting  of  the  soft,  the  other  of  the  hard  parts  of  worm-eaten 
cantharides,  the  portions  being  separated  by  a  sieve  of  ten  meshes  to 
the  inch.  The  result  was  less  successful,  as  a  considerable  amount  of 
fatty  matter  could  not  be  removed  by  the  petroleum  benzin,  but  remained 
intimately  associated  with  the  cantharidin,  being  insoluble  in  bisulphide 
of  carbon  and  other  solvents,  except  those  which  also  dissolved  the  can- 
