THE MANURE HEAP AND SEWAGE. 12$ 



present. Almost all of them will be reduced to simpler com- 

 pounds. The carbonaceous material will be reduced eventu- 

 ally, if the process is complete, into CO 2 and water, with the 

 liberation of hydrogen or perhaps marsli gas (CHJ. Such 

 gases would leave the liquid and join the atmosphere. The 

 nitrogenous material would suffer the decomposition which we 

 have already noticed, resulting in the production of ammonia, 

 and denitrification, which would be sure to occur, would still 

 further reduce this to free nitrogen. Such gases also would 

 be sure to join the atmosphere, unless held in solution 

 in the liquids. In short, the putrefactive processes, which 

 in the manure heap produce a loss deprecated by the agricul- 

 turist, would produce here exactly the result which the san- 

 itary engineer desires to reach, a destruction and dissipation of 

 organic material. 



Such changes will take place as readily in sewage as in ma- 

 nure or in the soil. Indeed observation and analysis show that 

 they commonly take place much more rapidly. In the first 

 place the organic matter to be acted on is generally in a 

 soluble or partly dissolved condition, and very easily acted 

 upon by bacteria. Secondly, the great abundance of water 

 facilitates the action, for bacteria require an abundance of water 

 for their best growth. Thirdly, the bacteria are present in ex- 

 treme abundance. All sewage contains bacteria in large num- 

 bers, although naturally the number varies. A common 

 sewage contains from 7,000,000 to 10,000,000 bacteria per c.c. 

 Among these bacteria are always large numbers of the various 

 decomposition bacteria, ready to seize upon the organic mate- 

 rial and decompose it with rapidity. Such sewage, if left to 

 itself, will undergo a rapid and quite complete decomposition, 

 which results in reducing large quantities of matter to a 

 gaseous state. Other parts are rendered perfectly soluble and 

 are completely dissolved in the water, so that the water of the 

 sewage is left in a comparatively pure state, frequently com- 



