REMARKS  ON  CUPREOUS  SODA  WATER. 
497 
reputation  for  the  sale  of  the  beverage  enables  them  to  dispose  of 
it  quickly,  thereby  tacitly  admitting  that  even  such  stores  are 
liable  to,  if  not  obliged  to,  employ  apparatus  unfit  for  the  purpose, 
did  not  the  short  contact  of  the  fluid  render  any  ill  effects  from  it 
impossible,  and,  of  course,  carrying  the  inference  that  in  small 
establishments  it  would  be  almost  impossible  to  prevent  the  sale 
of  cupreous  soda  water.  If  this  idea  was  acted  on,  consumers 
would  be  compelled  to  go  to  a  few  establishments  for  supply,  on 
the  penalty  of  being  poisoned  otherwise.  Now  we  believe  it  is 
quite  possible  that  good  carbonic  acid  water  can  be  furnished  by 
vendors  whose  sales  do  not  amount  to  more  than  one  or  two  foun- 
tains per  week,  as  we  know  by  trial  that  in  thoroughly  tinned 
fountains,  with  proper  tubes,  etc.,  the  water  may  be  kept  fur  weeks 
without  cupreous  impregnation.  The  difference  all  turns  on  the 
conscientiousness  of  the  manufacturer  in  attending  to  the  retinning 
of  the  fountains  at  proper  intervals,  and  on  the  pharmaceutist  in 
proper  attention  to  the  tubes,  stop-cocks,  and  other  portions  of  the 
apparatus  belonging  to  him.  There  is  no  difficulty  in  ascertaining 
the  condition  of  soda  water  if  the  apparatus  is  in  fault.  The  ad- 
dition of  a  few  drops  of  solution  of  yellow  prussiate  of  potash 
to  a  glass  of  the  suspected  soda  water,  placed  on  a  white  marble 
slab,  or  a  sheet  of  paper,  will  occasion  no  change  if  pure,  but  if 
e/en  a  minute  portion  of  copper  is  present,  some  shade  of  purplish 
brown  will  be  manifest  on  looking  down  through  the  fluid,  amount- 
ing, in  many  instances,  to  such  a  depth  of  color  that  the  ferrocya- 
nuret  of  copper  separates  in  flocks.  In  order  to  ascertain  whether 
it  is  the  draw-cock,  the  cooler,  or  the  fountain  that  is  in  fault,  let 
the  operator  draw  say  half  an  ounce  of  the  water  from  the  tube 
connecting  the  draw-pipe  with  the  cooler,  then  a  portion  from  the 
cooler,  and  a  third  portion  from  the  fountain  directly.  Let  him 
then  fill  test  tubes  of  equal  dimensions  with  each  specimen,  and 
add  a  few  drops  of  the  test  solution  to  each,  as  long  as  it  causes 
coloration.  By  comparing  the  tubes,  especially  by  looking  down 
through  the  liquid  with  the  tubes  held  on  white  paper,  it  can 
readily  be  seen  which  has  the  greatest  depth  of  color,  or  whether 
the  coloration  is  equal  in  all  ;  if  the  latter,  the  fountain  is  proba- 
bly most  in  fault ;  if  the  former,  the  fountain  may  be  either  less 
faulty,  or  in  some  cases  faultless,  in  wThich  instances  the  water 
drawn  from  it  gives  no  coloration  at  all. 
