3o8 
Magma  Magnesia. 
Am.  Tour.  Pharm. 
July,  19 17. 
to  prepare  the  magma,  is  simply  mixed  with  water,  allowed  to  stand 
for  twenty-four  hours,  shook  up,  and  the  process  is  completed.  We 
have  tried  that  method,  but  find  it  does  not  yield  as  satisfactory  a 
preparation  as  one  would  wish  it  to  be.  In  the  first  place,  the 
magma  is  rather  grayish  in  color,  probably  due  to  insufficient  puri- 
fication of  the  hydrated  magnesium  oxide.  Secondly,  the  magma 
does  not  stand  up  well ;  is  quite  gritty,  and  if  allowed  to  stand  for 
some  time,  cakes  into  a  solid  lump,  which  appears  rather  gluey  and 
is  very  hard  to  shake  up.  It  is  indeed  to  be  regretted  that  hydrated 
magnesium  oxide,  as  it  is  marketed  at  present,  falls  short  of  yield- 
ing a  satisfactory  magma;  for  the  fact  remains  that  this  method 
would  be  the  ideal  method.  It  is  to  be  hoped  that  the  manufacturers 
of  hydrated  magnesium  oxide  will  continue  to  work  with  the  chem- 
ical with  a  view  to  improving  it  so  that  eventually  it  can  be  made 
to  yield  a  satisfactory  product. 
Perhaps  it  would  not  be  amiss  right  here  to  draw  attention  to 
the  fact  that  the  beautiful  white  color,  which  some  very  popular 
brands  of  milk  of  magnesia  appear  to  have,  but  in  reality  do  not 
have,  is  achieved  by  bottling  the  magma  in  glass  bottles  of  a  strik- 
ingly beautiful  pale  blue  tint.  How  simple  and  yet  so  successful  a 
trick ! 
After  considerable  work  on  magma  magnesia,  it  has  been  our  ex- 
perience that  a  really  nice  magma  can  be  prepared  according  to  the 
X.  F.  Ill  formula,  somewhat  modified.  If  dried  magnesium  sul- 
phate is  substituted  for  the  ordinary  sulphate,  and  the  amount  of 
water  reduced,  no  difficulty  in  working  the  formula  will  be  experi- 
enced. It  is  a  strange  phenomenon,  yet  it  is  certain  that  dried 
magnesium  sulphate  exhibits  different  physical  properties  from  or- 
dinary magnesium  sulphate.  This  feature  is  clearly  brought  out 
in  making  magma  magnesia.  If  dried  magnesium  sulphate  is  used, 
a  nice  smooth  magma  is  obtained  which  subsides  very  rapidly,  in- 
deed so  rapidly  that  a  fresh  washing  can  be  given  it  every  ten  to 
fifteen  hours,  which  enables  one  to  have  the  preparation  finished  in 
less  than  a  week's  time ;  while  a  magma  prepared  exactly  according 
to  the  same  formula,  but  with  ordinary  magnesium  sulphate,  is 
rather  lumpy  and  requires  at  least  several  days  to  subside;  thus 
considerable  time  is  required  for  its  manufacture. 
The  following  formula  has  been  tried  a  number  of  times  by  dif- 
ferent workers,  and  has  always  produced  the  same  satisfactory 
results : 
