144  Purification  of  Drinking  Water.  {^JS;^ 
than  usual,  in  that  we  have  not  had  to  consult  a  physician  during 
this  time.  Another  interesting  observation  is  that  the  water  being 
more  palatable  than  boiled  water,  we  consume  larger  quantities, 
which  possibly  has  some  influence  on  the  general  bodily  condition. 
Believing  that  many  vegetables  may  also  be  a  source  of  infection, 
we  take  the  precaution  either  to  wash  the  vegetables  to  be  eaten 
raw  with  copper-treated  water,  or  to  place  them,  particularly  in  the 
case  of  lettuce  and  celery,  in  a  vessel  of  water  along  with  a  strip  of 
clean  copper  foil  and  allow  them  to  remain  from  two  to  four  hours 
with  occasional  agitation. 
The  use  of  copper  vessels  would  be  more  convenient,  but,  of 
course,  is  more  expensive.  I  have  also  thought  that  water  pitchers 
and  tumblers  might  be  partly  lined  with  copper  foil. 
From  my  own  experience  and  observations,  together  with  those 
of  others,  we  may  draw  certain  general  conclusions,  which  I  have 
summarized  as  follows : 
It  is  pretty  well  established  that  the  typhoid  organism  is  dis- 
seminated not  only  through  water,  but  also  through  air  and  food, 
and  may  retain  its  vitality  for  a  considerable  period  of  time. 
Typhoid  organisms  in  water  are  eliminated  by  filtration,  boiling, 
and  by  certain  biochemical  methods.  Of  the  latter,  the  use  of 
copper,  as  proposed  by  Moore  and  Kellerman,  is  probably  the  most 
efficient  and  at  the  same  time  the  most  practicable. 
While  exceedingly  minute  quantities  of  copper  in  solution  are 
toxic  to  certain  unicellular  organisms,  as  bacteria,  it  is  safe  to 
assume  that  the  higher  plants  and  animals,  including  man,  are  unaf- 
fected by  solutions  containing  the  same,  or  even  larger  amounts  of 
copper. 
There  being  a  number  of  factors  which  tend  to  eliminate  the 
copper  in  solution,  it  is  hardly  likely  that  there  would  be  any  copper 
in  solution  by  the  time  the  water  from  a  reservoir  reached  the  con- 
sumer if  the  treatment  of  the  reservoir  were  in  competent  hands. 
Many  plants  contain  relatively  large  quantities  of  copper,  and 
when  these  are  used  as  food,  some  of  the  copper  is  taken  up  by  the 
animal  organism,  but  there  are  no  records  of  any  ill  effects  from 
copper  so  consumed. 
