CONTRIBUTIONS  TO  PHARMACY. 
71 
mercury  completely  rubbed  down.  Indeed,  it  is  questionable 
whether  the  powder,  when  apparently  well  formed,  always  contains 
mercury,  as  a  compound  may  be  readily  formed  by  uniting  other 
coloring  substances  with  chalk,  to  imitate  blue  mercurial  powder ; 
and  I  think  I  have  met  with  such  imitations  several  times.  The 
blue  powder  that  I  have  procured  from  the  shops  has  generally  dis- 
appointed me  ;  and  for  a  number  of  years  I  have  prepared  it  myself 
according  to  the  following  method : 
Take  one  part  of  pure  starch  ;  eight  parts  of  prepared  chalk  ;  and 
sixteen  parts  of  mercury.  Reduce  the  starch  to  fine  powder.  The 
chalk  may  now  be  added,  and  after  being  well  mixed,  the  mercury 
can  be  united.  The  powder  must  next  be  moistened  with  water, 
but  not  to  the  extent  of  wetting  it ;  and  the  whole  rubbed  until 
nearly  dry,  when  the  mass  should  be  again  moistened  and  rubbed 
dry.  In  this  manner  the  process  must  be  repeated  from  time  to 
time,  as  may  be  convenient,  until  the  powder  assumes  a  uniform 
blueish  appearance.  After  the  chalk  seems  to  be  saturated  with 
the  mercury,  rub  the  mass  perfectly  dry,  and  then  moisten  it  suffi- 
ciently to  make  it  adhere  to  the  surface  of  the  mortar  by  pressing 
with  the  pestle.  By  carefully  passing  the  pestle  over  the  adhering 
mass,  so  as  to  render  its  surface  smooth  the  superfluous  mercury 
will  now  escape  from  it  in  small  globules  and  fall  to  the  bottom  of 
the  mortar,  and  the  separation  may  be  facilitated  by  striking  the 
bottom  of  the  mortar  against  the  table  repeatedly,  and  by  pouring 
the  mercury  over  the  surface  of  the  mass  where  any  globules  ap- 
pear. The  mercury  may  now  be  removed  from  the  mortar ;  and  as 
soon  as  the  mass  becomes  sufficiently  dry,  the  trituration  must  be 
renewed  and  continued  until  the  mass  becomes  a  smooth,  dry 
powder.  Prepared  according  to  this  method,  I  have  used  blue 
powder  in  my  practice  more  than  twenty-five  years,  and  have  uni- 
formly found  it  far  more  certain  in  its  operation  than  that  obtained 
from  the  shops.  I  prescribe  it  in  the  ordinary  doses,  or  nearly  so, 
and  yet  I  am  satisfied  it  is  stronger  than  that  in  general  use.  I  in- 
variably direct  it  to  be  administered  nearly  dry,  united  with  brown 
sugar,  and  to  be  mixed  in  a  cup  by  stirring  the  powder  and  sugar 
together  with  a  straw  or  the  point  of  a  knife.  The  dose  may  then 
be  taken  into  the  mouth  and  swallowed,  first  wTith  the  saliva,  and 
afterwards  with  a  mouthful  of  water.  This  powder  should  never 
be  mixed  in  a  silver  spoon,  or  any  other  utensil  possessing  an  affi- 
