Am.  Jour.  Pharm. 
May,  1909. 
Purification  of  Drinking  Water. 
225 
and  to  evolve  new  methods  of  procedure  whereby  the  general  excel- 
lence shall  not  only  be  maintained  but  advanced.  Such  is  the  careful 
supervision  of  these  great  water  plants  that  the  water  supplied  is 
always  maintained  at  the  highest  recognized  standards.  An  abstract 
from  Annual  Report  shows  a  reduction  of  both  turbidity  and  bacteria 
as  follows: 
These  results  show  a  change  in  the  quality  of  the  water  from  an 
intolerable  abomination  to  a  condition  quite  acceptable  from  its 
chemical,  hygienic,  and  aesthetic  sides. 
Another  important  bearing  of  the  laboratory  upon  the  effective 
working  of  the  plant  may  be  noted  in  the  following  incident: 
Clogging  of  the  niters  is  expected  to  occur  more  rapidly  during 
times  of  freshet,  as  in  the  spring  and  fall,  due  to  increased  turbidity, 
but  during  the  period  of  clear  water,  in  July  and  August,  filtration 
would  naturally  be  expected  to  go  on  without  much  hindrance.  It 
was  noticed,  however,  that  an  increased  difficulty  was  experienced 
and  that  the  beds  went  out  of  commission  even  more  rapidly  than 
with  very  turbid  water.  Here,  then,  was  a  mystery  to  be  unravelled. 
It  remained  for  the  laboratory  to  solve  the  problem,  which  they 
promptly  did.  The  investigation  disclosed  the  cause  to  be  located 
in  the  presence  of  a  minute  vegetable  growth  known  as  chloro- 
phycese  that  occurs  in  the  river  water  in  such  prodigous  numbers 
that  they  actually  plug  the  final  filters  more  rapidly  than  the  mud 
had  done  it  before.  This  incident  happened  prior  to  the  completion 
of  the  preliminary  filters.  Since  their  installation,  however,  this 
difficulty  is  rendered  impossible  because  the  growths  as  well  as  the 
earthy  sediments  are  removed  in  the  first  treatment. 
There  is  one  feature  of  the  filtered  water  that  every  one  has 
noted,  its  freedom  from  turbidity.  We  remember  very  distinctly 
the  repugnant  fluid  formerly  supplied.  After  every  storm  its  tur- 
bidity was  raised  to  any  degree,  and  it  remained  opaque  for  indefinite 
periods.  As  we  now  have  it  supplied,  there  is  no  perceptible  tur- 
bidity, regardless  of  the  weather  or  what  the  condition  of  the  river 
Average  reduction,  turbidity, 
Average  reduction,  bacteria, 
Maximum  reduction,  turbidity, 
Maximum  reduction,  bacteria, 
Per  Cent. 
99.46 
99-50 
100.00 
Minimum  reduction,  turbidity, 
Minimum  reduction,  bacteria, 
99.96 
88.90 
97.61 
