ADecX27t*}        Aerated  Water  containing,  etc.  577 
thinks  he  has  found  in  carbonic  acid.  In  fact,  he  has  ascertained  by 
experiment  that  the  bone  phosphate  dissolves  in  carbonic  acid,  and 
that  its  solubility  augments  with  the  pressure.  In  order  to  effect  the 
solution  easily  and  rapidly,  it  is  necessary  to  use  the  phosphate  in 
the  gelatinous  form.  On  the  other  hand,  however,  as  aerated  waters 
strongly  charged  with  carbonic  acid  have  a  special  medicinal  action, 
and  might  in  certain  cases  be  contra-indicated  or  badly  supported  by 
the  patients,  the  author  proposes  not  to  exceed  the  proportion  of  gas 
which  will  dissolve  in  water  under  the  ordinary  pressure  of  the  atmos- 
phere. Under  these  conditions,  a  glass  of  gaseous  water  will  dissolve 
and  retain  twenty-five  centigrams  of  tribasic  phosphate  of  lime,  which 
would  appear  to  be  sufficient  for  a  single  dose  that  might  be  repeated 
several  times  a  day. 
The  apparatus  necessary  for  producing  this  gaseous  phosphated 
water  is  very  simple.  Carbonic  acid  gas,  produced  in  the  usual  way 
and  well  washed,  is  allowed  to  bubble  into  a  milk  of  gelatinous  phos- 
phate of  lime  contained  in  a  reservoir.  After  the  passage  of  the 
gas  for  some  hours  the  current  is  stopped,  the  excess  of  phosphate  of 
lime  is  allowed  to  deposit,  and  the  clear  solution  is  decanted  into 
bottles  similar  to  those  used  for  natural  mineral  waters. 
The  water  so  obtained  is  limpid,  colorless,  and  inodorous,  and  has 
a  subacid  flavor.  Exposed  during  several  hours  to  the  air,  it  loses  a 
portion  of  its  carbonic  acid,  and  a  pellicle  forms  on  its  surface.  At 
a  later  period  it  becoms  turbid.  It  is,  therefore,  important  to  keep 
bottles  that  are  in  use  corked,  and  not  to  pour  out  the  water  long  be- 
fore drinking  it. 
The  presence  of  basic  phosphate  of  lime  in  this  water  may  be  easily 
recognized  by  the  following  reactions  : — 
(1.)  The  phosphated  gaseous  water  is  alkaline,  a  characteristic  in 
which  the  author  considers  it  differs  from  all  the  solutions  and  syrups 
hitherto  recommended,  they  having  a  strong  acid  reaction. 
(2.)  Boiling,  by  driving  off  the  gas,  causes  the  precipitation  of  the 
basic  phosphate. 
(3.)  Nitrate  of  silver  gives  a  yellow  precipitate  of  phosphate  of 
silver. 
(4.)  Ammonia  precipitates  basic  phosphate  of  lime. 
(5.)  Ammoniacal  sulphate  of  magnesia  causes  a  precipitate  of  am- 
monio-magnesian  phosphate. 
36 
