Am.  Jour.  Pharm.\ 
December,  1904.  / 
Correspondence. 
579 
purification  of  drinking  water  are  in  a  quantitative  sense  much  like 
filtration,  only  the  organisms  are  completely  destroyed. 
(3)  Pending  the  introduction  of  the  copper  treatment  of  water 
on  a  large  scale  the  householder  may  avail  himself  of  a  method  for 
the  purification  of  drinking  water  by  the  use  of  strips  of  copper 
foil  about  3  y2  inches  square  to  each  quart  of  water,  this  being 
allowed  to  stand  over  night,  or  from  six  to  eight  hours,  at  the  ordi- 
nary temperature,  and  then  drawn  off  or  the  copper  removed. 
CORRESPONDENCE. 
THE  PURIFICATION  OF  WATER  BY  MEANS  OF  COPPER. 
The  toxic  influence  of  even  very  minute  quantities  of  colloidal 
copper  and  of  copper  sulphate  on  certain  micro-organisms  having 
been  pretty  well  established  (see  pp.  553,  574),  the  only  other  question 
of  importance  that  arises  in  connection  with  their  use  for  the  purifica- 
tion of  water  supplies  containing  pathogenic  organisms  and  algae, 
is  the  one  as  to  their  effects  on  man.  Inasmuch  as  this  phase  of  the 
question  is  dependent  upon  physicians  and  pharmacologists  for  its 
elucidation,  the  editor  of  this  Journal  has  asked  several  members 
of  the  medical  profession  to  discuss  it. 
It  is  to  the  credit  ol  the  medical  profession  that  while  some  of 
those  asked  to  contribute  to  this  discussion  have  more  or  less  posi- 
tive convictions  on  the  subject,  others  have  been  frank  to  say  that 
their  observations  and  experience  in  this  line  of  investigation  have 
not  been  sufficient  to  warrant  them  in  giving  an  opinion  at  this 
time.  One  pharmacologist  writes:  "  As  I  understand  the  purifica- 
tion method,  the  quantities  of  copper  remaining  in  solution  are  so 
extremely  small  that  they  would  scarcely  be  harmful." 
Another  eminent  pharmacologist  writes  that  when  he  was  con- 
sulted by  a  city  official  to  give  an  opinion  as  to  whether  one  part  of 
copper  in  1,000,000  parts  of  water  would  be  harmful,  he  replied  that 
"  assuming  for  purposes  of  argument  that  the  copper  remains  in 
solution,  and  is  not  deposited  or  rendered  insoluble,  this  small 
quantity  could  not  be  harmful  to  our  citizens,  even  if  they  drank 
such  water  for  a  few  days,  since  our  ordinary  food,  as  bread,  meat, 
etc.,  all  contain  from  two  to  three  parts  in  the  million.  Some  tis- 
sues, like  the  liver,  contain  as  high  as  thirty  parts  in  the  million." 
