200 
Lead  Number  of  Asafetida. 
I  Am.  Jour.  Pharm. 
1       May,  1913. 
method  is  subject  to  too  many  variations  to  be  relied  upon  for 
determining  the  "  lead  number  "  of  either  selected  tears  of  asafetida 
or  possible  mixtures  of  asafetida  and  other  gum  resins. 
The  method  was  carried  out  as  follows : 
The  alcoholic  solution  of  the  alcohol  soluble  matter  is  evaporated 
upon  the  water  bath,  the  resin  heated  with  water,  stirring,  then 
cooled  (adding  ice  if  resin  does  not  separate)  and  the  water  de- 
canted. The  resin  is  dissolved  in  ether,  transferred  to  a  separator 
and  washed  with  water  until  the  water  shows  no  turbidity.  The 
ether  solution  is  filtered  into  an  exaporating  dish  and  the  solvent 
evaporated  on  the  water  bath.  Weigh  roughly  about  i.i  gm.  of 
the  above  resin  into'  a  tared  beaker  and  dry  for  5  hours  at  uo°  C, 
cool  and  weigh.  Dissolve  in  95  per  cent,  alcohol  and  transfer  to 
at  100  c.c.  measuring  flask  or  cylinder,  care  being  taken  that  not 
more  than  70  c.c.  of  alcohol  is  used.  Add  25  c.c.  of  a  4  per  cent, 
lead  acetate  solution,  make  up  to  mark  with  95  per  cent,  alcohol, 
mix  thoroughly  and  set  aside  over  night.  Mix  thoroughly  and 
filter  thru  a  fluted  filter ;  transfer  25  c.c.  of  the  filtrate  to  a  beaker, 
add  10  c.c.  water  and  evaporate  to  10  c.c.  on  bath ;  add  5  c.c.  10 
per  cent,  sulphuric  acid,  and  then  100  c.c.  alcohol.  Dissolve  all 
separated  resin  and  collect  the  PbS04  on  a  tared  Gooch  crucible, 
ignite  and  weigh. 
Run  a  blank  on  the  lead  acetate  solution  and  calculate  milli- 
grammes lead  absorbed  (  weight  PbS04  X  0.6830  =  Pb)  by  1  gm. 
of  the  resin. 
The  lead  acetate  solution  is  prepared  by  dissolving  4  grammes 
lead  acetate  in  20  c.c.  of  distilled  water  and  sufficient  95  per  cent, 
alcohol  to  make  100  c.c. 
The  method  as  recently  announced  calls  for  a  5  per  cent,  solution 
of  lead  acetate  and  80  per  cent,  alcohol  to  dissolve  the  resin  instead 
of  95  per  cent.,  otherwise  it  is  essentially  the  same. 
The  values  preceded  by  the  letter  "  S  "  were  determined  by 
Mr.  Nathan  Smith  to  whom  I  am  also  indebted  for  assistance  in 
preparation  of  the  purified  resins,  etc. 
Lead  Number  determination  experiments  were  made  upon 
selected  samples  as  follows : 
No.  1. — Broken  asafetida  tears  with  smooth  fracture,  yellowish 
but  not  pink  color,  21 5.1,  S  197.3. 
No.  2. — Tears  yellow  surface,  fracture  smooth,  white  or  pink 
turning  red  221,1,  S287.0. 
N0.3. — Resin  from  No.  2  heated  for  3  to  4  hour  periods  for 
