MERCURY — ITS  OXIDES  AND  ACETATES,  ETC.  271 
the  proportion  of  one-eighth  of  the  mercury  used,  is  of  great  ad- 
vantage, both  in  extinguishing  the  mercury  and  preventing  the 
revival  of  it  by  rubbing  between  the  fingers.  The  powder,  how- 
ever, dries  hard,  and  subsequent  pulverization  makes  the  mer- 
cury visible. 
When  prepared  by  washing  out  the  soluble  matter  with  warm 
water,  the  pasty  mass  spread  out  thinly  on  plates  of  glass  to  dry 
becomes  very  hard;  an  attempt  to  powder  it  increases  the  size 
of  the  globules,  sometimes  aggregating  them  so  much  as  to  be 
visible  to  the  naked  eye. 
The  difficulty  of  reducing  blue  mass  to  a  fine  powder  without 
aggregating  the  globules  of  mercury  and  the  hygrometic  condi- 
tion of  the  powder,  due  chiefly  to  the  honey  it  contains,  renders 
both  the  process  and  the  product  ineligible. 
The  following  process  gave  the  best  results  after  a  number  of 
varied  experiments : 
R  Finely  dusted  Elm  bark        .         1  part. 
"         "     Sugar  .  1  u 
Mercury     .        .        .  .  1  a 
Alcohol  .       .        .  q.  s. 
Rub  the  mercury  with  the  powdered  elm  bark,  adding  suffi- 
cient alcohol,  from  time  to  time,  to  maintain  a  pasty  consist- 
ence, till  the  mercury  is  completely  extinguished ;  then  spread 
the  ingredients  on  paper  to  dry.  The  mass  when  dry  does  not 
adhere,  and  is  readily  reduced  to  a  fine  powder  ;  then  mix  in  the 
sugar,  rub  till  thoroughly  mixed  and  pass  through  a  sieve  of  fine 
bolting  cloth. 
As  thus  prepared  the  powder  is  of  a  light  slate  color — about 
the  color  of  mercury  with  chalk  ;  under  the  microscope  it  showed 
globules  of  mercury  very  evenly  divided,  not  larger  than  those 
in  the  best  prepared  mass. 
If  desired,  a  portion  of  the  sugar  can  be  omitted,  and  replaced 
by  finely  powdered  rose  leaves. 
As  thus  prepared,  it  is  scarcely  entitled  to  the  name  of  pow- 
dered blue  mass,  but  fulfils  all  its  chemical  conditions. 
In  rubbing  mercury  with  powdered  elm  bark,  wet  with  alco- 
hol, the  mercury  is  rapidly  extinguished.  If  the  trituration  is 
continued  after  the  powder  becomes  dry  or  nearly  dry,  the  mer- 
