xii Contents 



PART III 



Bacteria and Sewage 103-134 



CHAPTER XII 



The Problem of Sewage-Disposal 103-111 



The cess-pool — ^The new method of the nineteenth centuiy 

 — Bacteria in sewage — Growth of the problem — Inland 

 communities and sewage-disposal — The source, com- 

 position and quantity of sewage. 



CHAPTER XIII 



Bacterial Purification op Sewage 112-124 



Sewage-farms — Sewage tanks and filter beds — Progress 

 in sewage-purification — Intermittent sewage-filtration 

 — Separation of bacterial activities — Temperature and 

 bacterial activities — Hydrolysis — Treatment of effluent 

 — Temperature and filter efiiciency — Inoculation — Kinds 

 of bacteria in filter beds and septic tanks — Loss of 

 nitrogen — Bacterial efficiency in sewage-purification — 

 Factory wastes and bacterial efficiency^ The working 

 capacity of bacterial filters. 



CHAPTER XIV 



Sewage-Irrigation . ... ... .125-134 



Economic value of sewage-irrigation — Sanitary value 

 of sewage-irrigation — Kinds of irrigation — Broad irriga- 

 tion — Intermittent and mixed irrigation — ^The crops 

 grown on sewage-farms — Preliminary treatment of 

 sewage for sewage-farms — Objections to sewage-farming 

 — Sanitary efficiency of sewage-purification. 



