194     MEDICINAL  VALUE  OF  THE  CANTHAMS  VITTATA,  ETC. 
1st.  500  grains  placed  in  a  retort  with  a  due  proportion  of 
water,  and  subjected  to  heat  carefully  regulated,  afforded  a  dis- 
tillate, slightly  opalescent,  and  having  the  peculiar  odor  of  the 
fly  in  a  marked  degree.  No  further  separation  of  the  oil 
occurred. 
The  distillate  was  then  agitated  with  ether,  the  ether  then 
separated  and  allowed  to  evaporate  spontaneously.  A  minute 
residue  was  obtained,  colorless,  possessing  the  strong  odor  common 
to  the  fly,  and  being  exposed  was  readily  dissipated. 
2d.  Allowing  the  substance  to  remain  in  the  retort,  it  was  then 
boiled  repeatedly  in  successive  portions  of  water  until  every  thing 
soluble  in  that  menstruum  was  extracted. 
The  residue  was  a  brown  pulverulent  mass,  totally  devoid  of 
vesicating  properties,  the  virtues  of  the  fly  being  totally  ex- 
hausted by  the  aqueous  menstruum. 
3d.  This  residue  yielded  the  green  oil  of  cantharides  when 
treated  with  sulphuric  ether. 
4th.  The  decoctions  previously  obtained  were  mixed  and 
evaporated  at  a  temperature  not  exceeding  212°  to  nearly  a  solid 
consistency. 
To  this  extract  was  added  alcohol  U.  8.  P.,  intimately  mixed, 
boiled,  and  strained  quickly. 
The  undissolved  residue,  constituting  the  greater  part  of  the 
matter  extracted  by  water,  was  of  a  dark  brown  color,  tenacious, 
insoluble  in  alcohol  or  ether,  precipitated  by  subacetate  of  lead 
and  alcohol,  acquires  a  sweetish  odor  on  exposure  for  a  short  time, 
and  is  found  to  possess  no  epispastic  properties. 
5th.  The  strained  alcoholic  solution  was  then  evaporated,  and 
yielded  that  principal  associated  with  cantharidin  usualty  known 
as  the  yellow  matter  of  cantharides.  It  was  deliquescent,  acid 
to  litmus,  soluble  in  alcohol  and  water,  and  has  the  remarkable 
property,  when  in  combination  with  the  active  principle  in  the 
fly,  of  rendering  it  soluble  in  water  and  alcohol,  in  which  men- 
strua in  its  pure  state  it  is  totally  insoluble. 
6th.  This  principle  was  then  subjected  to  a  moderate  heat, 
and  carefully  dried  so  as  to  admit  of  pulverisation.  Then  being 
reduced  to  an  extreme  degree  of  comminution,  intimately  mixed 
with  about  half  its  weight  of  very  fine,  pure  and  perfectly  dry 
animal    charcoal,  and  moistened  throughout  with  ether,  was 
