AmMa°rc&,T9w.rm-}      The  Technical  Analysis  of  Water.  121 
small  streams  before  it  reaches  the  sponge  layer,  because  the  water 
is  entered  at  the  bottom  and  passes  upward  through  the  various 
layers.  This  device  filters  water  at  the  rate  of  45,000,000  gallons 
per  acre  per  day,  of  such  a  quality  that  it  enables  the  hygienic 
filters  to  deliver  clean  and  wholesome  water  at  the  rate  of  6,000,000 
gallons  per  acre  per  twenty-four  hours — exactly  doubling  the 
capacity  of  these  filters.  The  commonly  accepted  rate  consistent 
with  good  work  is  not  over  3,000,000  gallons  per  acre  in  twenty- 
four  hours.  As  a  measure  of  economy  the  device  is  well  worth  its 
cost.  The  cleaning  of  the  sponge  layer  is  accomplished  by  the  aid 
of  machinery,  and  the  outfit  bears  a  strong  resemblance  to  a  well- 
equipped  laundry  establishment. 
At  each  washing  there  is  some  loss  of  sponge  material,  but  it  is 
not  serious.  The  cost  of  the  sponge  clippings  is  about  5  cents  per 
pound. 
To  the  drug-store  mind  sponges  would  not  seem  to  be  a  desirable 
substance  to  apply  to  this  purpose,  basing  an  opinion  on  experience 
gained  with  the  drug-store  sponge  in  active  service,  but  as  the 
sponges  in  the  filter  are  constantly  submerged,  they  do  not  seem  to 
be  subject  to  the  same  deterioration. 
THE  TECHNICAL  ANALYSIS  OF  WATER. 
By  W.  E.  Ridenour. 
The  manufacturer  of  special  chemicals  requires  the  analysis  of  a 
water  to  be  stated  in  grains  per  U.  S.  gallon  and  that  two  analyses 
of  the  same  water  made  at  the  same  time  shall  not  vary  more  than 
tV  §ra^n  on  eacn  constituent. 
As  upon  the  chemist's  report  he  determines  the  chemicals  to  be 
used  and  also  the  quantity  per  1,000  gallons  or  per  1,000  cubic 
feet. 
The  different  bases  and  acids  found  in  solution  in  the  water  must 
also  be  combined  according  to  chemical  affinities,  as  the  elements 
themselves  have  no  meaning  in  the  business  mind:  i.  e.f  the  chlorine, 
sulphuric  anhydride,  carbon  dioxide,  lime,  magnesia,  soda,  etc.,  must 
be  combined.  That  is,  the  elements  found  in  solution  must  be 
stated  as  they  exist  in  combination  in  the  water. 
The  scheme  of  water  analysis  used  in  the  laboratory  of  the  Geo. 
W.  Lord  Company  is  as  follows : 
