SEWAGE DISPOSAL 109 



nure is converted into soluble products. The decompos- 

 ing manure should, therefore, be protected from leaching. 

 Thoroughly packed piles that expose ilie minimum of sur- 

 face tend to conserve the value of the manure. The ac- 

 cumulation of manure in deep stalls in which sufficient 

 litter is used to absorb the liquid manure, and in which 

 the constant tramping of the animals excludes the air, is 

 undoubtedly the best way of handling manure. It can 

 best be used with sheep and feeding cattle rather than with 

 dairy cows. The direct application of the fresh manure to 

 the land is also an excellent method of conserving its fer- 

 tilizing value. 



Sewage disposal. The disposal of the waste material of 

 man represents an important problem to the family liv- 

 ing in the country. When great numbers of people are 

 crowded together, as in cities, and when to the household 

 waste is added the waste of great industrial establishments 

 like the packing-houses of Chicago, the problem becomes 

 still more important. The organic matter in this material, 

 ordinarily called sewage, must be decomposed by the action 

 of microorganisms into the simple mineral substances, the 

 salts of nitric, phosphoric, and sulphuric acids. The de- 

 composition of the organic matter must be so controlled that 

 it shall not become a nuisance or injurious to health. 



It is, of course, desirable, from the standpoint of conser- 

 vation of the elements having great fertilizing value, that 

 the organic matter be returned to the soil. In many of 

 the larger Oriental cities, the night soil is collected and 

 carried to the cultivated lands near the city. This process, 

 commendable as it may be from the standpoint of the con- 

 servation of plant food, can be used only where human 

 labor is cheap. 



The American and European cities use water as a vehicle 

 to transport the sewage from the point of production 



