CBRATUM  CANTHARIDIS. 
11 
CERATUM  CANTHARIDIS. 
By  William  R.  Warner. 
Take  of  Spanish  Flies,  in  fine  powder,  five  ounces. 
Alcohol,  -817  sp.  gr.  (95  per  cent,  vol.)  q.  s. 
Rosin,  three  ounces. 
Yellow  Wax,  six  ounces. 
Lard,  seven  ounces. 
Moisten  the  powdered  flies  with  the  alcohol  and  pack  in  a 
suitable  percolator  ;  gradually  pour  upon  it  the  alcohol  until  it 
passes  through  without  much  color,  which  will  require  usually 
about  two  and  a  half  pints.  Then  evaporate  by  a  gentle  heat 
to  the  consistency  of  a  soft  extract,  add  the  resin,  wax  and  lard, 
melt  them  together  and,  occasionally  stirring,  maintain  at  a 
temperature  of  2129  for  fifteen  minutes.  Strain  through  linen 
to  separate  the  extractive  and  other  insoluble  matter  that  may  be 
present,  and  stir  until  cool.  This  cerate  should  have  a  slight 
greenish  yellow  hue,  of  rather  firm  consistency,  and  possessing 
in  a  perfect  degree  the  active  properties  of  the  Spanish  flies. 
The  above  formula  for  Ceratum  Cantharidis  is  offered  as  a 
substitute  for  the  officinal  cerate  from  its  elegance  and  greater 
efficacy,  which  has  been  fully  attested.  Its  mode  of  preparation 
is  not  difficult,  will,  perhaps,  afford  more  uniform  results,  and 
the  additional  expense  from  use  of  alcohol  is  scarcely  worth 
considering,  as  this,  in  manufacturing  largely,  may  be  recovered 
by  distillation.  Slight  economy  may  be  practised  by  the  use  of 
hot  or  boiling  alcohol,  of  which  much  less  is  required  to  exhaust 
the  flies  of  their  active  principle.  Repeated  decocting  of  the 
flies  in  water  will  afford  an  aqueous  extract  which,  though  con- 
taining the  virtues  of  the  fly,  is  not  altogether  eligible  as  a  sub- 
stitute for  the  alcoholic  extract  in  the  preparation  of  this  cerate. 
The  heating  of  the  alcoholic  extract  with  the  ingredients  of  the 
cerate  affords  a  solution  of  cantharidin  in  the  oily  matter,  and 
at  the  same  time  a  separation  of  the  extractive. 
According  to  the  researches  of  Prof.  Procter,  the  active  con- 
stituent of  cantharides  in  an  isolated  state  is  sparingly  soluble  in 
cold  alcohol.  In  the  process  here  given,  however,  alcohol  is 
found  to  be  an  excellent  menstruum,  and  does  readily  dissolve 
the  cantharidin  while  it  is  associated  with  a  peculiar  yellow  ex- 
