128 KANSAS UNIVERSITY SCIENCE BULLETIN. 



In this short time no definite conclusions can be drawn. 

 However, the data obtained are suggestive of fields for investiga- 

 tion, and attention is called to the following things, as shown by 

 table III : 



The plant has not yet reached its maximum efficiency. 



Aeration in itself is of value in bringing about purification. 



Some purification is taking place in the second tank, but it 

 requires more time before any conclusion can be drawn as to 

 the changes which are brought about. 



In the analysis the amount of dilution is such as to give op- 

 portunity for error in the methods described by Phelps { Journal 

 of Infectious Diseases I, 327-340) for ammonia determinations. 



From May 9 to 16, the average amount of soap, lye, sawdust, 

 and toilet-paper — non-nitrogenous matter — was 625 grams ; 

 the amountof human excrement — nitrogenous matter — was 800 

 grams ; from the 16th to the 23d, the amount of soap, etc., was 

 1500 grams, the human excrement remaining the same ; however 

 there is nothing in the analysis indicative of what became of 

 the excessive amount of non-nitrogenous organic matter enter- 

 ing the tank. 



After the plant had been in operation for some time the hard- 

 ness of the effluents increased to about twice that of the city 

 water used in the toilet-room. This is just opposite to what was 

 expected, and at present cannot be accounted for. The hardness 

 of the city water was determined by the same soap solution as 

 was used in that determination of the sewage effluents. 



The average amount of non-nitrogenous matter entering the 

 plant is higher than the nitrogenous organic matter. 



