364 
FLUID  MAGNESIA. 
taneous  separation  of  sulphuret  of  iron,  which  appears  to  color 
the  suspended  sulphur  black,  still  the  quantity  of  sulphocyanuret 
of  potassium  resulting  therefrom  is,  even  after  continued  boiling, 
very  inconsiderable. — Ibid  from  Ibid. 
FLUID  MAGNESIA.  . 
»  By  Dr.  Thomas  Antisel. 
This  medicament,  introduced  to  the  profession  by  Sir  James 
Murray,  and  generally  adopted,  is  at  all  times  manufactured  of 
very  variable  strength.  By  Sir  J.  M.,  who  held  a  patent  for  its 
manufacture  in  Great  Britain  and  Ireland,  it  was  stated  to  be 
furnished  at  the  strength  of  14  grains  to  the  ounce.  Its  manu- 
facture being  commenced  in  this  city  about  a  year  since,  and  ha- 
ving received  a  bottle  from  the  manufacturers,  1  determined  the 
amount  of  solid  matter  and  of  magnesia  which  a  given  quantity 
would  yield. 
1.  On  evaporating  one  ounce  of  fluid  to  dryness  the  residue 
being  ignited  in  a  porcelain  crucible,  weighed  4.50  grains. 
2.  Digested  1  oz.  for  an  hour  to  expel  the  carbonic  acid,  which 
precipitated  a  portion  of  the  magnesia ;  then  added  caustic 
potass  until  the  precipitation  ceased  ;  precipitate  collected,  dried, 
ignited,  and  weighed  =  4.33. 
3.  The  residue  of  experiment  1,  treated  with  weak  hydro- 
chloric acid,  did  not  wholly  dissolve,  but  left  a  white  gritty  pow- 
der to  15  ;  this  dissolved  in  boiling  hydrochloric  acid,  and  on 
evaporation  to  dryness  and  ignition,  it  was  insoluble  in  the  same 
acid  ;  this  portion  was  silica. 
Now,  as  100  parts  of  ordinary  carbonate  of  magnesia  contain 
41.6  of  caustic  magnesia  (MgO),  so  from  experiment  2,4.33  gr. 
would  supply  10.41  grains  of  carbonate  of  magnesia  in  1  oz.  of 
liquid.  This  "American  Fluid  Magnesia,"  as  it  is  termed, 
does  not,  therefore,  contain  the  full  amount  of  magnesia,  which 
the  condensed  gas  would  dissolve,  by  nearly  one-third. 
Since  the  solvent  powers  of  carbonic  acid  upon  the  earths 
have  been  so  happily  introduced  into  medicine,  it  is  worth  con- 
sidering whether  a  solution  of  phosphate  of  lime  in  carbonic 
acid  might  not  be  used  with  advantage. — N.  Y.  Jour,  of  Pharm. 
