TREATMENT OF FARM SEWAGE. 87 
the agency of certain species of bacteria (see Chapter VII), it is no 
serious matter if some of the nitrogen is thrown away. 
TREATMENT OF FARM SEWAGE. 
Upon the ordinary farm the sewage problem is rarely of any im- 
portance, because of the small amount of material. The wastes 
which form the sewage in the city are kept separate on the farm and 
are not all treated alike. Part goes to the manure or compost heap, 
and later is returned to the soil with the manure. Part goes to the 
privy vault and is handled like manure; while still another part 
drains from the sink and is generally allowed to waste itself on the 
ground. A considerable portion of city sewage, like the refuse 
from factories, etc., has no counterpart on the farm. 
Nothing further need be said concerning the first of these 
portions. The contents of the privy vault have practically the 
same relations to bacterial decomposition and denitrification as 
manure, and should be handled in essentially the same manner. 
It is always emphatically necessary, however, to remember that 
the contents of the privy vault are far more likely to contain patho- 
genic bacteria than is barnyard manure, and it should, consequently, 
be much more carefully handled. That such material has been 
the means of distributing typhoid fever in many cases is surely 
demonstrated. The bacilli of this disease are voided by the patient 
in the excreta, and are thus sure to find their way into the vault, 
to be subsequently distributed over the fields, where they may 
percolate through the soil and pollute streams and wells. The 
contents of the privy vault should never be left in position where 
it can possibly pollute the water of either brook or well. Precaution 
ns should also be taken to prevent its distribution around the farm by 
means of soiled boots or tools which have been used in handling 
it. There is much more likelihood of finding pathogenic bacteria 
in human excrement than in that of domestic cattle, and the 
disease germs thus found are far more likely to be injurious to 
human health. Evidently the farmer should exercise much more 
care in disposing of the contents of his privy vault than in the use of 
