Am.  Jour.  Pharm.  » 
December,  1904.  j 
Purification  of  Water  Supplits. 
56i 
which  is  daily  being  used  in  quantities  a  hundred  times  greater, 
and  without  any  harmful  results  so  far  as  is  known.  The  fact  that 
the  copper  rapidly  disappears  from  most  waters,  and  that  at  least 
10  per  cent,  of  it  is  immediately  absorbed  by  the  algae  and  becomes 
insoluble,  need  not  be  taken  into  account,  although  it,  of  course, 
tends  to  make  the  method  more  secure  for  those  who  have  objec- 
tions to  the  presence  of  copper  in  food  or  drink,  when  they  know 
it  is  there. 
Very  naturally  after  it  was  noted  that  the  algae  were  so  suscepti- 
ble to  infinitesimal  quantities  of  copper,  it  seemed  worth  while  to 
test  the  effect  of  this  metal  upon  typhoid  and  cholera  germs,  these 
being  the  two  pathogenic  forms  which  are  most  commonly  conveyed 
by  water.  As  the  result  of  some  500  or  600  experiments,  it  was 
demonstrated  that,  while  these  bacteria  were  not  as  sensitive  as  the 
algae,  still  the  dilution  necessary  to  produce  death  was  sufficiently 
great  to  warrant  the  belief  that  under  certain  conditions  efficient 
sterilization  of  large  bodies  of  water  could  be  brought  about.  It 
should  be  stated  most  emphatically  and  clearly  understood  that  it 
was  not  supposed  for  a  moment  that  such  a  method  could  be  sub- 
stituted for  efficient  sand  filtration  or  any  other  means  now  in  use 
which  has  been  demonstrated  as  doing  the  work  thoroughly.  It 
was  believed,  however,  and  practical  tests  since  made  have  proved 
it,  that  in  cases  where  no  system  of  filtration  existed,  or  where  the 
filter  failed,  owing  to  the  storage  basin  being  flooded  by  surface 
drainage,  or  because  of  leakage  or  other  cause,  this  method  was 
not  efficient,  that  in  copper  sulphate  we  had  the  only  remedy  for 
such  emergency  cases.  It  should  be  borne  in  mind  that  nothing 
is  more  delicate  or  requires  more  intelligent  and  conscientious 
supervision  than  a  filter  plant.  Any  one  who  has  had  an  oppor- 
tunity to  visit  many  such  plants  throughout  the  country  and 
really  knowing  their  inside  workings,  as  it  were,  cannot  help 
being  astonished  at  the  low  rate  of  efficiency  frequently  main- 
tained. Consequently,  the  application  of  copper  sulphate  under 
such  circumstances  for  the  purpose  of  reducing  the  bacteriological 
content  has  been  used  successfully  in  enough  cases  to  demonstrate 
that  it  has  a  distinct  place  in  water  purification.  So  far  as  I  know,  its 
use  has  been  resorted  to  for  but  a  short  time,  or  until  the  source  of 
pollution  could  be  removed.  Whether  it  would  be  efficient  and 
proper  to  use  it  continuously  during  a  considerable  period  awaiting 
