Disposal of House Sewage. 295 



point of disposal. In the smaller towns and rural districts the above 

 method is not practical from a financial standpoint, and some simple 

 and economical plan must be resorted to. A common practice is to 

 drain this house sewage into a vault or cesspool, the surplus water 

 being permitted to soak into the soil. In open soils the water often 

 escapes so rapidly that the vault is soon filled with solid refuse. In 

 the more heavy soils, the pores are soon closed by the solid matter and 

 the waste flows out over the surface. It is only occasionally that the 

 soil conditions are right to permit the water to escape at the proper 

 rate, and even where these cesspools do work satisfactorily for a time 

 they will eventually fill up with solid matter or the escape of the liquid 

 be prevented entirely by the sealing of the porous soils by the material 

 carried in suspension. At the best, they saturate the surrounding 

 earth with disease germs that are liable to contaminate the water 

 supply or become offensive to the sense of sight and smell. 



DESIRABLE BACTERIA IN SEWAGE. 



It has been learned that under proper conditions this house refuse 

 that is so dangerous to health and offensive to the senses carries with 

 it the germs of a bacteria which will work its own destruction if the 

 proper conditions are provided. Occasionally a cesspool is reported 

 which has worked for years with entire satisfaction. The reason for 

 the satisfactory working of these occasional cesspools is due to the 

 fact that in their construction the conditions of light, air, heat, cur- 

 rents and discharge of the liquid matter were such that they afforded 

 the proper conditions for the growth and multiplication of these sewage 

 destroying bacteria. The conditions under which these bacteria thrive 

 have been studied and experiments conducted until the proper con- 

 dition for their growth is understood, and they are now considered of 

 great use for the purification of sewage not only of individual houses 

 but for the larger towns and small cities. 



CONDITIONS UNDER WHICH THESE BACTERIA THRIVE. 



It has been found that these bacteria thrive best where there is a 

 limited amount of light and air, a certain degree of heat and a surface 

 unbroken by currents. These conditions are secured by discharging 

 the sewage into a tank from which the light is excluded by a covering, 

 air being admitted through a small vent. Heat is supplied by the hot 

 water used in the sinks and lavatories, and that generated in the 

 tank itself by chemical action in the sewage. This heat is conserved 

 by having the tank partially or entirely buried in the earth. Cur- 



