Am.  Jour.  Pharm.  \ 
August,  1919-  -* 
A  New  Form  of  Calomel. 
539 
is  reduced  to  mercurous  chloride.  The  details  are  as  follows :  A 
solution  of 
Sodium  bicarbonate    6  grams. 
Pure  glucose    10  " 
Distilled  water    80 
is  added  to  a  solution  of  crystalline  magnesium  chloride,  7.5  Gms. 
in  20  Gms.  of  distilled  water.  This  mixture  is  then  added  to  the 
following  solution,  contained  in  a  flask  of  500  Cc.  capacity : 
Mercuric  chloride    1 1.5  grams. 
Hydrochloric  acid  (33.65  per  cent.)    10  drops. 
Distilled  water    100  grams. 
Carbon  dioxide  is  liberated,  while  mercurous  chloride  is  precipitated 
in  a  very  finely  divided  state.  To  complete  the  reaction,  the  flask 
is  heated  on  a  water-bath,  with  constant  agitation  until  no  more 
gas  is  evolved.  It  is  then  allowed  to  cool,  filtered,  and  the  precipi- 
tated mercurous  chloride  is  washed  with  cold  distilled  water.  This 
formula  yields  about  10  Gms.  of  calomel,  in  a  form  three  times 
bulkier  than  the  ordinary  preparation.  The  amounts  given  must 
be  strictly  adhered  to,  as  an  excess  of  magnesium  bicarbonate  would 
yield  magnesium  carbonate  mixed  with  the  calomel ;  while  an  insuffi- 
cient amount  of  magnesium  bicarbonate  would  result  in  leaving  un- 
changed a  portion  of  the  mercuric  chloride.  Tests  which  were  con- 
ducted by  the  author  showed  that  the  calomel  obtained  by  this 
method  is  ionized  in  water  to  a  greater  extent  than  the  ordinary 
product  (tested  with  diphenylcarbazid  and  sodium  monosulphide) , 
and  for  this  reason  its  therapeutic  activity  is  also  greater.  Experi- 
ments* showed  that  this  finely  divided  calomel,  in  the  presence  of 
organic  substances,  was  dissociated  into  metallic  mercury  in  a  state 
of  extremely  fine  subdivision;  consequently  by  this  method  is  it 
possible  to  employ  mercury  in  statu  nascendi,  thus  assuring  its  rapid 
absorption.  For  its  application  as  calomel  ointment  the  author  gives 
the  following  formula : 
Precipitated  calomel  (obtained  by  above  process)  . .  10  grams. 
Crystalline  magnesium  chloride    10 
Sodium  bicarbonate    7 
Thymol    0.15 
Camphor   0.35 
Arachis  oil    15 
Glycerite  of  starch    15 
Anhydrous  lanolin    20 
Distilled  water    25 
