Artificial Purification Of Water

A notable exanipie is f nraislied by the city of Berlín, in the interests of public health, in its treatrnent of water by 1 tificial pnrification, tbe present system Í being, as stated, the resnlt of extensivo j experiments for 15 yeara past. It seems that the attempt was rirst made to establish a plan of natural filtration by digging deep wells near the river and ! lakes trom which water was obtained, ! and ailowing the water to drain through thesoil frorn thesourceof snpply to the wells, froin which it was then pnmped to the city reservoirs, out this plan was abandoned on the fact being demonstrated that the water thus snpplied remained impuré. Artificial filtration was consequently substitnted, the water ] being filtered through sand, a large nnmber of filter basnas meeting this requirement. They are covered by roofs of stone, earth and sod, in order to prevent atmospheric contamination and the formation of ice in cold weather as well as to facilítate the frequent remováis of those impurities which gather npon the surface of the sand. The carefnl examinations of the water constantly made by official experts show that, whilothere isa small reduction in the quantity of organic matter in the ■ filtered water, the important fact also i appears that there is a retention of soiid-l imnnritipR and of laren nercpntaffe of