322  PHARMACEUTICAL  GLEANINGS  AND  NOTICES. 
Take  of  Cantharides  six  ounces. 
Ether  from  methylated  spirits,  13  fluidounces,  or  q.  s. 
Glacial  acetic  acid,  two  fluidounces. 
Gun  cotton,  half  an  ounce. 
^Methylated  spirit  of  wine,  seven  fluidounces,  or  q.  s. 
The  cantharides,  coarsely  powdered,  are  placed  loosely  in  a 
displacement  apparatus,  the  flow  of  which  can  be  regulated  by 
a  tap  ;  upon  this  is  poured  the  ether  and  acetic  acid  pre- 
viously mixed  together ;  after  the  whole  has  passed  through,  it 
wilf  be  found  that  the  debris  has  retained  by  absorption  seven 
fluidounces,  which  must  be  displaced  by  the  gradual  addition  of 
an  equal  bulk  of  methylated  spirits.  If  properly  done  there  is 
not  the  least  danger  of  the  admixture  of  the  spirits  with  the 
percolated  menstruum,  as  the  animal  substance  of  the  flies  swells 
considerably  under  the  prolonged  influence  of  the  spirits,  so  that 
the  same  bulk  will  be  insufficient  to  quite  displace  the  ether. 
The  ethereal  solution  should  then  be  made  to  measure  exactly 
15  fluidounces  by  the  addition  of  a  little  spirit,  and  may  then 
be  converted  into  collodion  by  the  addition  of  the  gun  cotton." 
Mr.  Tichborne,  after  asserting  that  the  Mylabris  cichorii 
may  be  substituted  for  the  cantharides,  (a  fact  well  known  to 
us  here,)  gives  the  following  method  of  applying  his  collodion  : 
"  The  part  upon  which  the  vesicle  is  to  be  raised  should  be 
painted  with  the  vesicant  to  the  desired  extent,  bearing  in  mind 
that  the  blister  produced  always  extends  to  about  one-tenth  of 
an  inch  beyond  the  margin  of  the  space  covered  by  the  collo- 
dion. Care  should  also  be  taken  that  there  is  a  considerable 
thickness  of  collodion  upon  the  surface.  To  ensure  this,  the 
brush  should  be  passed  over  and  over  again  until  about  half  a 
drachm  has  been  used  to  the  square  inch,  or  less  when  operating 
on  a  tender  epidermis.  It  is  desirable  to  cover  the  surface  with 
a  piece  of  oiled  silk  or  sheet  gutta  percha,  as  it  hastens  the 
action  of  the  collodion. 
In  ten  minutes,  or  a  quarter  of  an  hour  if  the  cuticle  is  hard, 
*  Methylated  spirits  is  common  alcohol  mixed  with  a  certain  portion  of 
•wood  spirit  or  methylic  alcohol  to  prevent  its  internal  use,  and  in  which 
condition  the  excise  duty  is  greatly  reduced  with  a  view  to  its  use  in 
manufacturing. 
