240     VESICATING  ACTION  OF  CANTHARIDATE  OF  POTASSA. 
usually  too  strong  in  hydrocyanic  acid,  and  requires  to  be  di- 
luted. The  author  adds  only  one  half  of  the  alcohol  to  the  con- 
tents of  the  still,  the  other  half  going  into  the  receiver,  whereby 
a  water  of  slight  turbidity,  not  of  a  milk-like  appearance,  is  ob- 
tained. Distillation  over  free  fire  invariably  yields  a  weak 
water,  probably  in  consequence  of  unavoidable  partial  overheat- 
ing. 
The  author  has  also  used  peach  kernels,  with  the  following 
result:  95  lbs.  of  the  same  yielded,  by  cold  expression,  25  lbs. 
of  filtered  clear,  faintly  reddish  yellow  oil,  resembling  benneseed 
oil ;  by  warm  pressure  8  lbs.  filtered  oil  somewhat  darker,  60 
lbs.  press  cakes  and  2  lbs.  loss  including  the  residue  upon  the 
filters.  The  60  lbs.  press  cakes,  equal  to  about  92  lbs.  kernels, 
yielded,  when  treated  as  described,  92  lbs.  water,  from  2  oz. 
of  which  8  grains  dry  cyanide  of  silver  was  obtained,  so  that  an 
addition  of  about  18  lbs.  distilled  water  was  requisite  to  reduce 
it  to  the  strength  of  the  Pharmacopoeia,  viz.  :  6f  grs.  AgCy 
from  960  grains  of  the  water.  The  water,  as  thus  obtained  from 
peach  kernels,  is  identical  with  that  from  bitter  almonds. — Ar- 
cMv.  der  Pharm,,  Bee,  1869,  226-229. 
ON  THE  YESICATING  ACTION  OF  CANTHARIDATE  OF 
POTASSA. 
By  E.  Delpech. 
The  author,  after  referring  to  the  ordinary  blistering  cerate 
of  cantharides  of  the  Codex,  and  criticising  its  resinous  and  fatty 
ingredients  and  its  uncertainty,  suggests  that  we  should  look  to 
cantharidin,  and  says  that  a  mixture  of  elastic  collodion  400 
parts,  and  cantharidin  one  part,  spread  on  adhesive  plaster, 
possesses  a  very  energetic  vesicating  power. 
The  volatility  of  cantharidin,  even  at  ordinary  temperatures, 
the  author  alleges  as  a  reason  for  seeking  some  means  of  fixing 
this  principle,  and  having  found  the  memoir  of  Messrs.  Massing 
and  Dragendorff  in  a  German  journal,  deems  the  views  therein 
contained  afi'ord  the  means  sought. 
These  authors  consider  cantharidin  (C^^H^O^)  as  an  anhydride, 
which  in  its  combinations  with  bases  fixes  two  equivalents  of 
