THE  AMEEIOAN 
JOURNAL  OF  PHARMACY 
JUNE,  igii 
DRIED  MAGNESIUM  SULPHATE. 
By  W.  a.  Puckner  and  L.  E.  Warren. 
The  Committee  of  the  American  Pharmaceutical  Association  for 
standards  of  unofficial  drugs  and  chemical  products  having  con- 
sidered Dried  magnesium  sulphate  "  the  subject  was  assigned 
to  the  senior  author  of  this  paper  as  referee  for  the  preparation  of 
tentative  standards.  Accordingly  provisional  academic  standards 
for  the  substance  were  prepared  and  submitted  for  criticism  to  a 
number  of  manufacturers  of  chemicals  and  to  several  chemists 
whom  it  was  thought  would  be  interested.  At  the  same  time  several 
brands  of  the  product  were  purchased  and  examined. 
Dried  magnesium  sulphate  is  official  in  several  of  the  foreign 
pharmacopoeias.  In  the  Pharmacopoeia  formerly  official  in  Austria 
the  method  directed  for  the  preparation  of  the  product  was  to  dry 
the  crystallized  magnesium  sulphate  first  upon  the  water  bath  with 
stirring  and  then  on  a  sand  bath  until  a  loss  of  43  per  cent,  should  be 
attained.  The  composition  of  the  residual  salt  was  supposed  to 
correspond  approximately  to  the  formula  MgSO^  +  HoO.  Such  a 
salt  should  contain  about  87.0  per  cent,  of  anhydrous  magnesium 
sulphate.  In  the  last  edition  of  the  Austrian  Pharmacopoeia  it  is 
directed  to  dry  the  salt  on  the  water  bath  at  100°  with  stirring  until 
36  per  cent,  of  the  original  weight  has  been  lost.  The  formula 
of  such  a  salt  should  be  approximately  MgS04+2H20,  corre- 
sponding to  about  77.0  per  cent,  anhydrous  magnesium,  sulphate. 
The  directions  given  by  the  German  Pharmacopoeia  (ed.  5)  are  to 
dry  the  salt  in  a  porcelain  dish  on  a  water  bath  until  it  has  lost 
from  35  to  37  per  cent,  of  its  weight.  Such  a  salt  should  contain 
from  75.15  per  cent,  to  77.54  per  cent,  of  anhydrous  magnesium 
(261) 
