52 KANSAS ACADEMY OF SCIENCE. 
salts of iron. The effect of this is not only to complete the oxidation of organic 
matter in solution, but also to hasten coagulation and destroy any excess of alka- 
linity there may be in the treated water; after which give final agitation and 
allow the water to become quiescent, when all the impurities in the water, now 
all in a state of suspension, will be precipitated by sedimentation. 
When settled, the water is taken off from near the surface by a floating pipe, 
clear, soft, free from bacteria, and sterile to the development of micro-organisms. 
The rate of precipitation depends on the condition of the water and the tem- 
perature. That of the water-supply of the city of Topeka at a temperature of 
sixty degrees is four feet per hour. 
This process, by making a filter of the now all insoluble impurities and by 
sedimentation, passing them down through the water, instead of by filtration 
passing the water through the filter, and by the accumulation of impurities in the 
body of the filter, resulting in the deterioration of the apparatus, provides for 
the complete realization of Doctor Lewin’s ideal water purification, and effects 
the following results: 
Ist. The removal from the water of the earth salts renders the water soft. 
2d. The removal of the organic matter sterilizes it to the development of 
micro-organisms and the support of bacterial life. 
3d. Aerating the water renders it more palatable, when used for drinking, 
and allows of the more rapid formation of steam in boilers required for industrial 
uses. 
The cost of installation per square foot of surface will not exceed that for sand 
filters, while the rate of passage of water will be as twelve to one. The cost of 
operation will practically be that of the cost of reagent. 
