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IOWA ACADEMY OF SCIENCES. 



It is a well known fact that the simplest and best methoi 

 of destroying organic matter, that is liable to provide 

 favorable conditions for the growth of disease germs, is to 

 destroy it by burning or oxidation. If the matter is in a 

 solid condition and dry naturally, burning is the most suit- 

 able. If in solution and a large quantity of water is pres- 

 ent other means must be used. The modern process of 

 bacterial purification of sewage is therefore simply using 

 the nitrification process to oxidize the organic matter and 

 ultimately changing the nitrogenous matter to nitric acid. 

 The raw sewage or that which is designated as the man- 

 hole sample contains the organic matter in its most stable 

 form. The raw sewage on passing into the septic tank 

 undergoes a process which is complicated from a chemical 



