12 
Magma  Bismuthi. 
IAm.  Jour.  Pharm. 
j    January,  1914. 
The  formulas  proposed  direct  ammonia  water  to  be  used  to  pre- 
cipitate the  bismuth  nitrate.  This,  in  our  experience,  leads  to  con- 
siderable trouble  trying-  to  wash  the  resulting  Magma  free  from  the 
excess  of  ammonia.  It  takes  a  great  deal  of  water  to  do  so  and  even 
if  one  has  succeeded  in  getting  the  final  washings  to  no  longer  react 
with  phenolphthalein  the  Magma  itself  will  always  give  a  strong 
reaction.  To  reduce  the  amount  of  ammonia  water  leads  to  a  reaction 
in  the  opposite  direction,  giving  a  decided  acid  reaction  which  causes 
the  gradual  solution  of  the  bismuth  hydroxide.  Furthermore,  when 
the  Magma  is  poured  on  a  strainer  for  the  purpose  of  washing  it, 
the  surface  of  the  Magma  very  soon  develops  a  metallic  coating 
which  certainly  points  to  a  decomposition  going  on  and  may  be  due 
to  exposure  to  air.  Unfortunately  this  is  the  only  way  the  Magma 
can  be  washed  because  distilled  water  has  the  property  of  causing 
the  Magma  to  curdle  into  large  flaky  masses,  taking  up  considerable 
water  and  holding  it  so  that  it  is  utterly  impossible  to  get  the  Magma 
to  settle  in  order  to  wash  it  by  decantation,  thus  preventing  undue 
exposure  to  air. 
Attention  should  also  be  drawn  to  the  fact  that  the  amount  of 
bismuth  subnitrate  used,  results  in  too  thick  a  Magma.  Further- 
more, 80  grams  of  bismuth  subnitrate  cannot  be  satisfactorily  dis- 
solved in  60  c.c.  of  nitric  acid.  It  takes  i  c.c.  of  nitric  acid  for  every 
gram  of  bismuth  subnitrate  to  be  dissolved. 
However,  with  some  modifications  the  proposed  official  formula 
will  give  satisfactory  results.  In  the  first  place  the  amount  of 
bismuth  should  be  somewhat  reduced,  then  ammonium  carbonate 
should  be  substituted  for  ammonia  water,  and  lastly,  distilled  water 
containing  i-iooo  sodium  chloride  should  be  used.  By  using  am- 
monium carbonate  the  resulting  Magma  is  not  nearly  so  alkaline,  it 
will  not  react  with  phenolphthalein  but  will  and  should  react  alkaline 
toward  methyl  orange.  It  therefore  does  not  require  nearly  so  much 
washing.  It  only  needs  to  be  washed  until  it  is  practically  tasteless. 
The  use  of  this  small  amount  of  sodium  chloride  in  distilled  water 
prevents  the  curdling  of  the  Magma,  and  it  therefore  can  readily  be 
washed  by  decantation,  no  strainer  being  required.  After  sufficient 
washing  it  is  allowed  to  settle  to  the  required  volume,  which  usually 
takes  about  a  week. 
Spigot  water  can  also  be  used  in  place  of  distilled  water  if  it  has 
been  previously  boiled  with  i  per  cent,  magnesium  carbonate  for 
