THE PURIFICATION OF WATER WITH BLEACHINGPOWDER

We have recently referred¹ to the use of ozone for the purification of drinking-water and have dwelt on the fact that the high or indeterminate cost of the various ozonization processes stands to some extent as a barrier to the general introduction of this method. It might be added further that ozone is not the only substance that can be employed for the "practical sterilization" of water, and that from a chemical point of view other substances are theoretically available for the treatment of large public supplies. Experiments lately conducted on the Jersey City water-supply appear to bear out this view.² Commercial bleaching-powder, an impure product the active ingredient of which is hypochlorite of calcium, has been used increasingly in the disinfection of sewage effluents during the last few years, and on at least one occasion (Maidstone, England, 1897) it has been used to disinfect a public water-supply