ON  THE  COLLECTION  OF  SOME  INDIGENOUS  DRUGS.  411 
or  filtered  solution  into  that  of  the  lead  salt,  or  to  the  sulphate 
diffused  in  water,  and  heated  nearly  to  boiling,  as  long  as  a  pre- 
cipitate forms,  or  the  intensity  of  color  increases.  After  the 
brown  oxide  has  settled,  the  supernatant  liquid  is  drawn  off  and 
the  precipitate  repeatedly  washed. 
The  presence  of  free  alkali  or  of  carbonate  or  acetate  of  soda 
is  essential,  since  they  serve  to  decompose  or  dissolve  any  chlo- 
ride of  lead  forming. 
In  regard  to  Overbeck's  method  of  preparing  the  deutoxide, 
it  must  be  carried  in  mind,  that,  although  the  ferrid-cyanide  of 
potassium  serves  to  oxidize  the  protoxide  of  lead  in  an  alkaline 
liquid,  as  soon  as  the  free  alkali  present  is  taken  up  by  the  ferro- 
cyanide  or  converted  into  carbonate  from  the  air,  an  inverse  re- 
action takes  place.  For 
KO+PbO+K3  Fe2  Cy6+ Aq=Pb02+2  (K2  Fe  Cy3)+Aq ; 
but  Pb02+2  (K2  Fe  Cy3)+Aq=K3  Fe2  Cy6+Ko+PbO+Aq— 
L  e.,  deutoxide  of  lead  in  contact  with  ferro-cyanide  of  potassium 
forms  ferrid-cyanide  of  potassium,  hydrated  oxide,  and  some 
carbonate  of  lead  with  free  or  carbonate  of  potassa  in  solution, 
the  carbonic  acid  being  taken  up  from  the  atmosphere. 
At  the  same  time  it  may  be  remarked,  that  this  latter  reaction 
forms  the  very  best  means  of  preparing  a  pure  red  cyanuret  of 
potassium  and  iron  on  a  small  scale. 
Yours,  most  obedient,  Feed.  Feist  Mayer. 
Philadelphia,  August,  1856. 
A  FEW  HINTS  RELATIVE  TO  THE  COLLECTION  OF  SOME 
INDIGENOUS  DRUGS. 
By  The  Editor. 
It  is  a  matter  of  some  importance  to  the  thorough  pharma- 
ceutist to  keep  in  mind  the  proper  time  of  gathering  plants  and 
barks,  roots,  leaves  and  other  parts  of  plants,  in  reference 
to  laying  up  a  store  for  future  use  and  for  the  manufacture  of 
quantities  of  preparations  requiring  them  to  be  used  at  the  period 
of  their  greatest  medicinal  power. 
Wild  Cherry  Bark. — According  to  the  results  of  Mr.  Perot, 
•  see  vol.  xxiv.  page  109,  of  this  Journal,)  the  proper  period  of  col- 
