492  American  Pharmaceutical  Association.    {A  octo°bUerr,^907ym' 
the  drug  firmly  and  exhaust  by  slow  percolation  with  chloroform^ 
receiving  the  percolate  in  a  Gordin's  distilling  flask.  Distil  off 
most  of  the  chloroform  by  means  of  a  water  bath,  and  blow  air 
through  the  flask  to  remove  the  last  traces.  Add  10  c.c.  of  liquid 
petrolatum  and  1 50  c.c.  of  hot  water  to  the  residue  in  the  distilling 
flask.  Heat  nearly  to  the  boiling  point  on  a  water  bath,  and  agitate 
several  times  while  keeping  at  this  temperature.  Draw  off  the 
aqueous  solution  through  a  small  filter  into  a  separatory  funnel. 
Repeat  this  operation  with  three  more  portions  of  75  c.c,  50  c.c, 
and  25  c.c.  of  water.  Cool  the  mixed  aqueous  liquids,  add  a  little 
hydrochloric  acid  and  extract  by  shaking  with  four  portions  of 
chloroform.  Evaporate  the  chloroform  solution  in  a  tared  flask  or 
beaker  on  a  water  bath.  The  solution  must  be  removed  from  the 
water  bath  while  some  chloroform  remains,  and  the  evaporation 
completed  in  a  current  of  air,  as  decrepitation  occurs  when  the  can- 
tharidin  begins  to  crystallize.  The  canfharidin  is  then  purified  in 
the  manner  described  by  Self  and  Greenish,  as  follows :  Wash  the 
crystals  with  three  portions  of  2-5  c.c,  2-5  c.c  and  I  c.c  of  a  mix- 
ture of  equal  parts  of  absolute  alcohol  and  petroleum  ether  saturated 
with  cantharidin,  pouring  the  washings  through  a  small  filter. 
Then  wash  the  crystals  and  filter  with  petroleum  ether  until  the 
filtrate  leaves  no  appreciable  residue  on  evaporation.  Wash  the  filter 
with  a  little  chloroform,  receiving  the  filtrate  in  the  vessel  containing 
the  greater  portion  of  the  cantharidin.  Evaporate  the  chloroform 
in  a  current  of  air  and  dry  at  ordinary  room  temperature  in  a  va- 
cuum desiccator  until  of  constant  weight. 
The  Estimation  of  Iron  in  Scale  Salts.  . 
By  Frank  R.  Eldred  and  C.  M.  Pence. 
The  authors  found  that  the  results  obtained  by  the  iodometric 
method  were  all  lower  than  the  gravimetric  results,  and  that  this 
was  due  to  the  presence  ol  ferrous  iron.  In  order  to  oxidize 
all  of  the  iron  to  the  ferric  condition,  they  found  that  the  citric 
or  tartaric  acid  present  must  be  completely  oxidized.  The  only 
practical  method  of  oxidation  found  was  by  means  of  concen- 
trated sulphuric  acid.  The  scale  salt  (0-5  gramme)  was  placed  in 
a  500  c.c  Kjeldahl  flask,  20  c.c.  of  concentrated  sulphuric  acid  and 
10  grammes  of  potassium  sulphate  were  added,  and  the  flask  heated 
until  only  a  pale  yellow  color  remained.    The  contents  of  the  flask 
