WASTES, City, Disposal of. The public wastes of a city may be grouped into three classes: (1) sewage; (2) city refuse; (3) trade refuse. The first class is specifically treated under the title SEWEAAGE. The third class con sists of such material as earth from excavations, refuse from building operations, manure from Emery stables, slatOiter-house offal, etc., and the packing litter from stores. This is usually and properly cared for under the law by private contractors. The second class, which must be cared for inteipal &Tartu • curnmotil of street cleaning,. 1. divisible into: (1) household refase; and (2) street refuse. The first ink ',tub , garbage, ashes, rubbish (paper, rags. broken glass and crockery.
tonics. tin can ' r and rubber scrap), and general sweepings. sac sewliti insists of horse droppings, pavement wear, fallen leaves, dead animals, material falling from carts, and snow. When these have been collected, it is neces the department of street cleaning to the most economical and least obnoxious final disposition of the various products of its activity. _Many, and indeed most, of t: ma terials collected lave a definite and consi•krable value when separate from material of other classes, hut a mixture of the various letols of refuse has no value except the little wh 1, can by separating the materiais by picking. In any large city the proper treatment of these materials calls for their collection in five separate classes: (I) Street sweepings; (2) dead animals; (3) household garbage and mar ket waste; (4) ashes; (5) household rubbish— cans, bottles, paper, rags, bits of metal—and trade waste. When a city population exceeds say 100.000, the amount of waste is sufficient so warrant this classification, because the re sulting economies will counterbalance the at tendant trouble and expense of keeping and collecting the materials separately.
(1) Street sweepings consist of about two thirds horse droppings and one-third dust and scrap of one kind and another. These sweep ings are not satisfactory as a lowland filling be cause of the large proportion of orfanic matter ; and on the other hand the material has small valise for fertilising purposes because even well kept stable manure has a value of only about $2 per ton, wholesale. on the basis of the price of
manufactured fertilizers; and street sweepings, from their admixture with other dirt, have a fertilising value of only about $1.35 per ton. It is evident that such material cannot be shipped far, because its value would soon be equaled by for handling and transportation; and the boat disposition that can be made of it is to send it out as a farm and garden dressing u far as its fertilising value will pay the freight. Before the days of high-grade fertil isers, suck material had a relatively higher value; bat nowadays, only in small cities where inasket gardens and farms are not greatly distant From the centre of population. have =yet sweepings any commercial value at the point of collection. In 1840 New York City sold its street sweepings and manure for $38,711; in 1850 the amount received was $38,898; in 1860 the amount was $17,928; and aY reeepits from this source ceased not many yaws later. The increasing use of automobiles has reduced the percentage of manure in the sweepings to less than 50 per cent. In smaller cities, however, while the cost of sweeping the streets will apparently always be a charge on the citizen, the value of the sweepings collected from paved streets ought to pay for their final deposition.
(2) In the matter of dead animals, it is customary to contract with some individual or firm for their prompt collection and removal; and though this is considered a service and is nearly always paid for by the city, yet the value recovered by the contractor from the hides, hones, grease and fertiliser-material goes a long way toward equaling the expense of col lection and disposal; and there is good reason the value of this material when scientifically treated is sufficient to meet the total expense.