ADeimber!llm '}        Purification  of  Water  Supplies.  563 
that  many  physicians  evidently  do  not  consider  it  as  poisonous  as  it 
is  supposed  to  be.  When  we  remember  that  copper  in  water  is 
100  times  more  efficient  as  a  germicide  than  carbolic  acid,  fifteen  or 
twenty  times  more  than  formalin,  and,  in  fact,  nothing  is  known 
which,  when  free  from  organic  matter,  is  so  deadly  to  germs  and 
harmless  to  man,  it  certainly  seems  that  the  beneficial  results 
obtained  by  the  physician  are  easily  explained. 
In  conclusion,  then,  I  would  say  that  in  spite  of  a  considerable 
number  of  articles  appearing  which  seem  to  clearly  demonstrate 
that  copper  in  such  small  quantities  will  not  destroy  algae  and  cer- 
tain pathogenic  bacteria,  the  fact  remains  that  it  has  been  done  and 
is  being  done  in  millions  of  gallons  of  water  in  various  parts  of  the 
country.  It  is  like  the  old  arguments  against  the  Atlantic  cable,  or 
the  treatise  carried  by  the  "  Great  Eastern  "  on  her  first  trip,  scien- 
tifically demonstrating  the  impossibility  of  such  a  ship  crossing  the 
ocean.  It  is  also  interesting  to  note  that  without  exception  the 
amount  of  copper  necessary  to  produce  death  of  both  algae  and 
bacteria  in  a  large  reservoir  has  always  been  less  than  the  theoreti- 
cal amount  determined  in  the  laboratory  by  the  use  of  aquaria  and 
test  tubes. 
It  is  probable  that  there  will  always  be  a  certain  amount  of  oppo- 
sition to  the  use  of  copper  for  the  purification  of  water  just  as  there 
is  to  vaccination  or  antitoxine,  but  as  more  and  more  cases  are 
added  to  the  list  of  supplies  successfully  treated  without  harm  to 
the  consumer,  this  aspect  of  the  question  will  disappear.  This  is 
well  illustrated  by  the  attitude  of  the  French  Government  which 
originally  maintained  such  rigid  laws  against  the  use  of  copper  in 
canned  goods  and  otherwise,  but  as  the  Prefecture  of  Police  of  Paris 
recently  wrote  : 
"Up  to  the  year  1899  the  subject  of  the  possible  bad  effects  on 
the  health  of  the  people  by  the  introduction  of  sulphate  of  copper 
in  the  preparation  of  preserved  vegetables  had  not  been  so  much 
studied  as  it  has  of  late,  the  scientific  opinion  being  divided.  But 
since  that  time  the  Consulting  Committee  has  been  renewed,  and 
has  again  taken  up  the  question  and  passed  on  the  experiments 
made  by  private  parties  both  as  to  the  quantity  of  copper  that  the 
human  body  can  consume  without  danger  to  health,  as  well  as  the 
proposition  that  the  various  preserved  foods  that  are  colored  green 
may  contain.   From  these  experiments  they  came  to  the  conclusion 
