586 TRANSACTIONS OF THE AMERICAN INSTITUTE. 



The imperfect action of l)rick sewers, with sizes entirely disproportioned 

 to their ordinary flow, which deposit their solid contents a portion of the 

 time and discharge tliem under the impulse of rainfall or unusual water 

 supply, must affect any analysis of their flow, in proportion to their special 

 conditions of action. An analysis of Edinburgh sewage water, which is 

 under constant supply, gives 62 grains of soluble and 244 of insoluble 

 matter per gallon. This is equivalent to 1 grain in 229, while 1 in 600 has 

 been assumed as a general mean, or 116.7 grains per gallon. 



Examinations of this class, which have been extensively made, tend to 

 correct the general idea of difficult sewage flow, and entirely divest the 

 subject from any doubts on this point. Sewage matter may be carried 

 through pipes or elevated by pumps, about as easily as water, under proper 

 regulation. 



The proper utilization of sewage matter, pertains to the doctrine of 

 restitution, alluded to in the introduction, and involves the consideration 

 of what may be taken as a duty on one side, and a serious waste on the 

 other. 



Experimental science has shown that the nitrogen and other valuable 

 constituents, annually produced by each person in any community, amount- 

 ing to an average of fifty-seven pounds, solid matter, is sufficient for the 

 supply of not less than two pounds of bi'ead per day, or over 800 pounds 

 of grain per annum, the estimated value being $1.91 in gold. Similar 

 researches have shown the value of sewage water, which includes and 

 increases this source of value, to be about 4.39.100 cents per ton. On this 

 basis, the value of the New York, sewage, estimated from the water sup- 

 ply at 200,000 tons per day, is $3,204,100 per annum in gold. 



It is stated from a reduction of the analysis of the Dorset square sewer, 

 with a solid content of 209.7 grains per gallon, that in 100 tons of similar 

 solid matter 57 are of no value, the remainder being 30.10 tons organic 

 matter, 1 ton potash, 2.63 tons soluble phosphate of lime and 1.27 tons 

 insoluble, and 8 tons ammonia, valued at $3,006, and of this value the 

 ammonia makes $2,235. 



Here, then, we have but 8 tons in 100, of high value, to produce the 

 ammonia and the phosphate of lime, or 11.81 tons, of concentrated manure, 

 worth $2,811, it is necessary to reduce 31,638 tons of sewage water or 

 6,960,360 gallons. 



Various attempts have been made to concentrate sewage water, so as to 

 make its manure merchantable, but the enormous dilution of water has 

 hitherto prevented their commercial success. The quantities of useless 

 matter to be moved and disposed of have proved too formidable, in weight, 

 in space and in expense to justify any extensive operations in utilization 

 of sewage by the process of concentration. 



The city of Paris provides for the removal of all its cess-pool contents 

 to Montfaucon. The estimate of cost, in 1850, for the removal of 230,000 

 cubic metres, was $414,000, and the income from the poudrette manufac- 

 tured was considerably less than the cost of simple transportation. We 

 have here another practical illustration of the mechanical difficulties 

 which surround the process of artificial concentration, and which go to 

 show that the cost of reduction is not justified by the prospects of income. 



