180 MARKET DAIRYING 



inch gas pipe as shown in Fig. 64. The liquid is with- 

 drawn from a point near the middle of the tank as in- 

 dicated by the discharge pipes. The eight-inch space 

 above the discharge permits the accumulation of organic 

 matter. The discharge from 'B into C, is the same as 

 that from A into B ; but the discharge pipes are of neces- 

 sity lower by ah amount indicated by the dotted lines. 

 Compartment C discharges intermittently by means of 

 an automatic syphon. 



The sewage becomes gradually purified in its passage 

 through the tank, and as it flows from the last section 

 it is nearly as clear as water, but has a slightly sour odor, 

 which it seems to retain and which is in no way objection- 

 able. The purified sewage has been kept for weeks with 

 no sign of the development of putrefactive odors. 



The discharges should be arranged as shown in Fig. 

 65. This arrangement will cause the least mixing of old 

 and new sewage. There is no discharge from A into 'B 

 until the second day's sewage flows into A. Similarly 

 there is no discharge from B into C until the second 

 discharge into B, etc. The sewage, therefore, requires 

 from three to four days in its passage through the tank. 



Cost of Septic Tank, A double partition tank, 12 

 feet square and 4j^ feet deep, constructed of concrete 

 consisting of one part cement, two parts sand and four 

 parts gravel, will cost approximately $50.00 when the 

 walls are five inches thick. 



SEWAGE DISPOSAL FROM DWELLING. 



The open privy and the cesspool of kitchen slops are 

 objectionable not only in so far as they affect the dairy 

 house, but also in that they constitute a source of danger 

 to the members of the family in ways entirely discon- 

 nected with the milk supply. With the dairy house 



