For many years it has seemed to thoughtful persons that permitting sewage, either from single houses or from larger communities, to be turned into streams was a mistaken policy because of the waste of manurial elements involved. It has long been understood that, in order to maintain the fertility of the soil, a constant application of fertilizers was necessary, and, while undoubtedly many farms are managed without any such repeated applications, the more scientific and modern farmer believes to-day that the frequent and abundant use of fertilizer is the foundation of his success. In ordinary sewage there exists a certain amount of fertilizing elements. Two prominent English chemists, not many years ago, proved by their analyses that in ordinary sewage there existed the essential elements of a good fertilizer to the value of $2 per year for each person contributing to that sewage. Other chemists, working at the problem in other ways, have reached about the same result, and there can be little doubt of their accuracy if the fertilizing elements alone are considered. In applying these figures to the sewage of a city the difficulty has always been that the fertilizing elements have been so thoroughly covered up with the large volume of water present in the sewage that it has been practically impossible to separate them from the water. Thus, in a city of 100,000 persons, the fertilizer in the sewage might, indeed, be worth $200,000, but to realize this amount it must be separated from the 10,000,000 gallons of water—a task which is so tremendous, if not impossible, as to make the value of the fertilizer of no account. In those parts of the country where the water itself has a value, as in the irrigated lands of the West, the fertilizing elements of the sewage would be added to the value of the water, so that sewage used for irrigation would be worth not merely the value of the water alone, but also the value of the fertilizer present in that water. Another difficulty in making use of the combined water and fertilizer is that the large amount of water involves a large area of land and suitable soil, on which irrigation may be practised, in the immediate vicinity of the city. This combination of agricultural soil of suitable texture at a suitable price for farming operations is so seldom found that this in itself usually precludes any application of the use of sewage for irrigation.