Dr_ Zacharias has identified the animalcula known as flag(Hata, which multiply rapidly and discolor surface waters. Rhizopods, Including diffingia and other genera; and in /a:ono which are the highest type of Protozoa, are also microscopic. Some are free-swim ming and others attached animalcula. They exist is countless colonies and some of them are in ternal parasites_ These infest reservoirs and other potable waters. The larvae of chin:twi nes are found in tipper layers of sand of water works in vest colonies. Green and blue known in Germany as *water blossoms,' :oogiorts, beggiatoo and innmnerable other micro-organisms infest waterworks, form slimy organic patches and undergo putrefactive changes. These decompose and produce odors and give water an unpleasant taste. George T. Moore and Dr. Karl F. Kellerman of the United States Department of Agriculture recommended the use of copper sulphate, but that does not always destroy all the typhoid bacilli and is a dangerous chemical to use, m aga in the smallest and when so used it is less efficient than the chlorides. Therefore it has not come into general use.
Nearly all the processes of sterilization are of recent discovery and those in general use are ridding potable waters of most of their c bacteria. Prior to their discovery ago, they were the causes of epidemics that wasted away communities and historians referred to them as pestilences and It may be assumed that polluted water as many human lives as the wars of all the ages.
Progressive nations are fast coming to realize that impure water is one of the greatest known menaces to health and to life itself. In this modern era the researches of scientists and experiments by health authorities have demon strated that most pathogenic bacteria and nearly all hying organisms in surface and other graters may be eliminated therefrom and all awls waters may be made safe for potable and all other uses.
Communities are no longer limited to lakes, mountain streams, springs and other ground sources for their water supply, but may draw raw water from riven, streams, lakes and ponds provided such waters be treated by some of the processes heretofore mentioned, that will render such waters pure and wholesome, as is being done by scores of cities in this and other countries. The water supply of a community a DOW largely a matter of purification, and saute turbid or bacteria-laden waters are not desirable on account of the expense involved m carrying on the processes of porificultem, still if other adequate sources he not avail able, river and other surface waters may he made safe for potable purposes. Thus it is possible for communities to obtain their supply from nearby surface waters.
The Hudson, the Ohio, the Mississippi, the Niagara, the Saint Lawrence, the Thamo‘, the Seine, the Rhine, the Rhone, the Elbe, the Danube, the Volga, the Nile, the Ganges, the Irrawaddy, the Yangtse-Kiang and scores of other rivers, as well as the Great Lakes in North America, the British, Swiss, Italian, African and innumerable other lakes are the sources of the water supply for millions of population. When such waters are scientifically treated by some of the processes hereinbefore described, they are safe and palatable. The importance of preserving all such surface waters from artificial contamination has led to the enactment of many laws to prevent such contamination. In America and Europe water supply authorities are usually empowered to acquire catchment areas and in some instances large parts of watersheds to prevent artificial contamination as well as to procure additional sources as has been done by New York City in acquiring the Catskill watershed and certain British cities in acquiring large additional areas to ensure wholesome water supplies. Rather slowly the public conscience is being enlightened and awakening to the dangers of the contami nation of water supply sources, in permitting the inflow of sewage, effluents from industrial plants, gas refuse, chemical works and other artificial wastes, all of which pollute and render waters noxious in their natural state. Most of these, however, are susceptible of such treat ment as to ensure their wholesomeness for potable purposes.
The introduction and general adoption of scientific processes for the purification of water for municipal and domestic purposes herein before described and others have necessitated the discontinuance of the use, or the demolition of many old and the installation of many new waterworks in this and other countries. The needs of each community and the physical con ditions of the territory of each whence its supply must come, as well as the water sources them selves, become matters of public investigation and of scientific study. This was demonstrated in the undertaking on the part of the city of New York to obtain its additional water sup ply, commencing in 1896 and continuing for 20 rt.-ars or longer. Such progress has been made in the scientific treatment of water for mu nicipal purposes, that, in addition to a score or more of processes for its purification in most any state, its acidity may be neutralized, as at Mocsley, England, it may he softened by any one of several processes, or it may be hardened and it may be deferrircd as in Germany to get rid of the microscopic erenothrix and other bacteria absorbing iron into their tissues and cIt sing water mains.