392 
Some  Recent  Literature. 
[Am.  Jour.  Phnrm. 
I     August,  1904. 
cases  be  sufficiently  toxic  to  prevent  the  growth  of  polluting  forms 
of  algae,  it  would  be  necessary  to  drink  over  20  quarts  of  the  water 
a  day  before  an  amount  of  copper  sulphate  which  is  recognized  as 
harmless  would  be  introduced  into  the  system,  while  it  would  take 
more  than  50  quarts  to  produce  unpleasant  or  undesirable  effects. 
There  are  also  two  other  factors  to  be  considered  which  would 
seem  to  render  the  danger  from  the  use  of  copper  sulphate  in  the 
manner  prescribed  entirely  nil.  (1)  In  most  cases  the  use  ©f  a  solution 
of  maximum  dilution  (r  to  1,000,000)  would  be  sufficient  to  kill  all 
forms  and  would  perhaps  not  have  to  be  resorted  to  again  for  at  least 
some  time,  or  at  most  very  much  weaker  solutions  could  be  used. 
(2)  Very  little  of  the  copper  would  be  found  in  the  water  after  a 
few  hours,  it  being  combined  by  the  algae  and  precipitated  in  other 
ways. 
The  point  to  be  borne  in  mind  in  applying  the  copper  sulphate  is 
that  it  should  be  thoroughly  distributed.  The  method  recommended 
and  used  by  the  Department  of  Agriculture  is  as  follows  :  Place  the 
required  number  of  pounds  of  copper  sulphate  in  a  coarse  bag — a 
gunny  sack  or  some  equally  loose  mesh — and,  attaching  this  to  the 
stern  of  a  rowboat  near  the  surface  of  the  water,  row  slowly  back 
and  forth  over  the  reservoir,  on  each  trip  keeping  the  boat  within 
10  to  20  feet  of  the  previous  path.  In  this  manner  about  100  pounds 
of  copper  sulphate  can  be  distributed  in  one  hour.  By  increasing 
the  number  of  boats,  and,  in  the  case  of  very  deep  reservoirs,  hang- 
ing two  or  three  bags  to  each  boat,  the  treatment  of  even  a  large 
reservoir  may  be  accomplished  in  from  four  to  six  hours.  There  are 
a  few  other  details  to  be  observed  in  some  cases,  but  as  the  Depart- 
ment desires  that  those  contemplating  the  use  of  the  method  con- 
sult with  them  first  before  making  a  test  of  the  method,  these  will 
not  be  given. 
It  remains  to  be  said  that  the  method  has  been  tested  in  water- 
cress beds  having  an  extensive  growth  of  algae,  and  also  in  water 
reservoirs,  and  that  the  results  have  been  very  encouraging. 
In  summarizing  their  experiments  with  pathogenic  bacteria,  the 
authors  state  that  at  ordinary  temperatures  I  part  of  copper  sul- 
phate to  100,000  parts  of  water  destroys  typhoid  and  cholera  germs 
in  from  three  to  four  hours.  The  copper  can  be  eliminated  from  the 
water  with  considerable  ease,  and  thus  is  afforded  a  practical  method 
of  sterilizing  large  bodies  of  water  when  this  becomes  desirable. 
F.  Y. 
