I 
^fei^b^Mo?1*}       The  Copper  Treatment  of  Water.  575 
The  method  used,  however,  was  not  published  at  that  time ;  but 
after  several  years'  experimenting  it  was  given  for  the  first  time  in 
a  Bulletin  of  the  Bureau  of  Plant  Industry,  published  on  May  7th  of 
this  year,  an  abstract  of  which  appeared  in  the  August  number  of 
this  Journal. 
I  think  it  can  be  said  that  at  the  present  time  there  is  not  a  doubt 
in  the  minds  of  engineers  and  others  that  the  copper  method  pro- 
posed by  Dr.  Moore  and  Mr.  Kellerman  in  this  Bulletin  is  the  only 
efficient  one  for  removing  algae  from  water  in  reservoirs  and  in 
streams,  and  that  this  can  be  done  without  affecting  the  higher 
plants,  as  water-cress ;  or  animal  life,  as  fish,  and  so  on. 
While  various  explanations  might  be  offered  to  show  why  such 
extremely  minute  quantities  of  copper  sulphate  as  1  part  to 
i,000,coo  or  even  50,000,000  parts  of  water  is  sufficient  to  kill  the  uni- 
cellular and  filamentous  algae,  and  yet  not  affect  multicellular  plants, 
whose  cells  are  as  delicate  in  structure  as  those  of  the  algae,  it  seems 
to  me  that  this  is  in  a  measure  due  to  the  fact  that  in  the  algae  the 
entire  individual  is  comprised  in  a  single  cell,  which  performs  all 
the  vegetative  as  well  as  reproductive  functions,  and  being  entirely 
surrounded  by  the  water  containing  the  copper  sulphate,  all  the  life 
processes  of  the  plant  are  affected,  there  being  no  way  for  it  to  dis- 
tribute the  solution  to  other  cells,  and  thus  by  a  dilution  minimize 
the  toxic  action  of  the  copper.  Or  if  some  of  the  cells  in  the  multi- 
cellular plant  are  destroyed  or  injured  by  exposure  to  the  solution, 
others  are  formed  to  take  their  place  from  the  more  or  less  deep- 
seated  meristematic  cells.  It  is  true  that  the  idiosyncrasies  in  these 
organisms  should  also  be  borne  in  mind,  some  of  them  being  more 
resistant  than  others. 
If  the  explanation  be  a  valid  one,  it  is  reasonable  to  suppose  that 
this  principle  of  action  would  apply  to  other  unicellular  organisms,  - 
as  the  bacteria  ;  and,  indeed,  Dr.  Moore  has  shown  that  a  solution 
of  copper  sulphate,  1  part  to  100,000,  is  sufficient  to  destroy  typhoid 
and  cholera  organisms  in  from  three  to  four  hours. 
It  was  to  be  expected  that  the  proposal  of  a  method  for  the  puri- 
fication of  water  supplies,  involving  the  use  of  copper  sulphate, 
would  arouse  considerable  discussion.  In  the  first  place,  the.  ques- 
tion would  arise  as  to  the  poisonous  effects  of  the  copper  on  man. 
Secondly,  a  question  would  arise  to  capitalists  and  others,  who  are 
investing  large  sums  of  money  in  filtration  plants,  as  to  whether 
