HYDRARGYRUM  CUM  CRETA,  ETC. 
387 
A  specimen  of  this,  which  has  been  kept  in  a  tall  slender  loosely 
stopped  bottle  of  white  glass,  for  two  years  and  four  months, 
now  yields  upon  analysis  a  large  proportion  of  both  oxides, 
(See  6th  analysis  below.)  This  preparation,  in  its  present 
condition,  when  administered  to  adult  men  in  ordinary  doses,  still 
retains  its  proper  mild  character  to  such  a  degree  that  its  action 
would  not  attract  ordinary  attention.  But  in  the  cases  of 
children,  especially  in  that  class  of  diseases  in  which  it  is  com- 
monly prescribed,  it  is  found  to  be  rather  too  active  for  the 
indications  to  its  use,  though  it  does  not  produce  vomiting  at  all. 
It  is,  nevertheless,  undoubtedly  a  bad  preparation,  through  too 
long  trituration  and  bad  keeping,  but  serves  its  purpose  of 
clearly  exhibiting  the  necessity  for  close  attention  and  accurate 
observation  in  the  process  of  preparation. 
The  best  process  for  Hydrargyrum  Cum  Creta,  as  far  as  the 
writers'  experience  goes,  is  as  follows : — 
Introduce  the  mercury  with  a  portion  of  the  chalk  into  a 
strong*  bottle  of  double  the  capacity  required,  and  shake  the 
mixture  actively  as  originally  proposed  to  Dr.  Coxe  of  New 
Orleans,  by  Mr.  W.  Hewson  of  Augusta,  Ga.  (See  Am.  Jour, 
Pharmacy,  vol.  22.  pp.  316  et  seq.)  When  upon  a  smooth 
compressed  surface  of  the  powder,  the  mercury  is  no  longer 
visible  to  the  naked  eye,  it  is  to  be  well  triturated  with  the 
remainder  of  the  chalk  until  a  fine  smooth  grey  powder  is 
obtained.  It  is  then  immediately  put  up  in  small  vials  to  be 
well  secluded  from  light  and  air. 
From  the  fact  that  very  few  pharmaceutists  make  these  pre- 
parations, it  becomes  much  more  important  to  have  a  means  of 
testing  the  character  of  those  of  the  common  market  upon  which 
they  depend  for  supply,  and  therefore  the  writer  has  been  at  some 
pains  to  fix  upon  the  following  practical  easy  tests,  which  he 
believes  to  be  capable  of  general  and  indi3criminate  application, 
at  the  same  time  that  they  are  reliable  within  practical  limits. 
The  powder  should  be  of  a  fine  clear  deep  grey  color,  rather 
of  the  lively  silver  tinge,  than  of  the  dull  leaden  color.  It 
should  be  entirely  free  from  any  rose,  or  "  ashes  of  roses"  tint; 
— and  the  powder  should  be  a  little  cumulative  or  clammy,  and 
not  at  all  mobile  or  sabulous. 
A  little  heap  of  it,  pressed  upon  a  dark  surface  with  a  smooth 
