248 



BACTERIA, YEASTS, AND MOLDS 



filled with water no bacteria and no gas can pass from 

 the sewer into the sink. If the joints of the sewer pipes 

 are tight and the traps are full of water, there is no dan- 

 ger that anything from the sewage can come into the 

 rooms. The traps, however, occasionally get emptied of 

 water, and then gases may pass up from the sewers. 

 Moreover, the insides of these 

 traps become breeding places 

 for certain kinds of bacteria, 

 though rarely disease bacteria, 

 and may in time become full 

 of them. It is therefore de- 

 sirable to pour some kind of 

 disinfectant occasionally into 

 the bowls and sinks. A weak 

 solution of carbolic acid, one 

 part to twenty, or a solution 

 of chloride of lime, one part 

 to twelve, put into bowls and yig. 8o. Diagram showing the 

 sinks will disinfect the traps. principle of two kinds of traps 

 It is also an excellent plan to separating washbowls from 



S6W6rS. 



pour boiling water frequently 



down sinks, bowls, and closets, for this not only helps 



to clean but helps also to disinfect. 



A worse danger to a household are Uakj/ sewer pipes. 

 If these are poorly laid, the contents of the sewer 

 may ooze out into the cellar or soil under the cellar 

 and become a source of considerable danger. Leaking 

 sewer pipes in a house are a serious menace. The 

 evils from sewer ^g-^j have, however, been overrated. Sewer 

 gas itself is not capable of producing any specific disease. 



