174 
Assay  Processes. 
Am.  Jour.  Pharm. 
April,  1917- 
amount  of  drug  used.  Preparations  containing  alkaloids  are  simi- 
larly treated.  They  are  first  evaporated  to  a  small  bulk  and  then 
the  extraction  is  carried  out  as  above  outlined. 
Cantharides. 
Cantharides  is  assayed  by  macerating  15  Gm.  of  the  drug  with 
150  mils  of  a  mixture  of  2  volumes  of  benzene  and  1  volume  of 
benzine  to  which  has  been  added  2  mils  of  HQ.  It  is  allowed  to 
stand  10  hours  then  warmed  to  40 0  C.  and  maintained  at  this  tem- 
perature and  frequently  agitated  for  three  hours  and  cooled.  100 
mils  are  decanted  and  evaporated  to  about  5  mils.  To  the  evap- 
orated solution  are  added  5  mils  of  chloroform  and  set  aside.  Af- 
ter the  solvent  has  evaporated  an  equal  volume  of  10  mils  of  de- 
hydrated alcohol  and  benzine  saturated  with  cantharidin,  are  added 
to  the  crystals  and  allowed  to  stand  15  minutes.  The  liquid  is  de- 
canted through  a  pellet  of  cotton  and  the  crystals  washed  with  suc- 
cessive portions  of  the  saturated  cantharidin  solution  to  remove  fat 
and  coloring  matter  and  the  washings  passed  through  the  cotton. 
The  cotton  is  then  washed  with  warm  chloroform  and  the  washings 
added  to  the  beaker  containing  the  crystals  and  the  solvent  evapo- 
rated by  a  blast  of  air  and  the  crystals  are  dried  at  6o°  C.  and 
weighed.  The  official  requirement  is  that  cantharides  should  con- 
tain not  less  than  .6  per  cent,  of  cantharidin. 
Assays  Needed. 
The  revisers  of  the  U.  S.  P.  have  performed  an  excellent  piece 
of  work,  but  the  assays  for  a  large  number  of  preparations  are  just 
as  essential  as  the  assays  of  the  substances  from  which  they  are 
made,  and  these  should  have  been  included.  While  it  is  true  that 
the  articles  entering  into  the  composition  of  these  preparations  may 
be  up  to  the  official  requirements,  what  assurance  is  there  that  the 
preparations  made  therefrom  are  of  standard  strength?  While 
these  standards  will  hold  in  check  the  manufacturers  of  chemicals 
and  the  jobbers  selling  the  official  drugs,  etc.,  there  is  nothing  in 
the  official  requirements  to  hold  a  pharmacist  who  may  attempt  to 
make  his  preparations  deficient  in  strength. 
The  following  preparations  should  have  included  an  assay 
method:  Emulsions  of  asafcetida  and  cod  liver  oil;  especially  a  test 
for  the  former  to  show  that  it  had  not  been  prepared  from  the  tinc- 
ture.   The  glycerites,  boroglycerite  and  tannin ;  the  spirits  should 
