CARBONIC  ACID  WATER  APPARATUS, 
105 
union  of  the  generator  and  fountain  or  fountains,  and  in  em- 
ploying bi-carbonate  of  soda  in  lieu  of  chalk  or  whiting  as  the 
source  of  the  gas,  with  the  further  peculiarity  that  the  carbonate 
is  gradually  admitted  to  the  acid  instead  of  the  acid  to  the  car- 
bonate. The  low  price  of  bi-carbonate  of  soda,  its  larger  yield 
of  gas,  and  its  affording  a  very  soluble  salt  with  sulphuric  acid, 
are  additional  reasons  for  its  use,  when  employed  by  the  retail, 
dealer  or  small  manufacturer.  According  to  the  maker,  the 
cost  of  charging  a  twelve-gallon  fountain  is  from  37 \  to  50  cts., 
or  about  three  cents  per  gallon.  The  generator  and  fountains 
are  calculated  to  resist  considerably  more  pressure  than  they  are 
subjected  to,  which  is  ordinarily  about  200  lbs.  to  the  square 
inch,  or  thirteen  atmospheres,  and  this  amount  of  gas  pressure 
can  be  attained  in  fifteen  or  twenty  minutes. 
Figure  2  represents  the 
apparatus  with  a  single 
fountain,  which  is  sufficient 
for  the  ordinary  demand  of 
a  retail  establishment ;  but 
where  the  consumption 
equals  several  fountains  a 
day  it  is  preferable  to  use 
that  with  two  fountains, 
(fig.  1)  which  will  enable 
the  supply  to  be  kept  up 
without  interruption.  I  is 
the  fountain  ;  D,  the  acid 
vessel ;  13,  the  receptacle 
for  the  soda  salt ;  E,  the 
washing  vessel  through 
which  the  gas  is  made  to 
pass ;  A  the  handle  of  the 
sliding  rod  which  opens  the 
valve  in  the  soda  vessel  and 
permits  its  descent  on  the 
acid  ;  C,  a  large  screw  joint 
connecting  the  soda  and  ; 
acid  compartments  ;  II  is 
an  agitator  to  facilitate  the  "=lFi{r.  2. 
absorption  of  the  gas ;  G  is  a  stop-cock  to  control  the  flow  of 
