Polytechnic Associatiox. 655 



over a large surface of land, where it undergoes a partial filtration, 

 before it enters the river. 



Under ordinary circumstance, where water-closets are generally in 

 use, we may safely state that at least four-fifths of the substance that 

 must necessarily enter the sewers, and which is subject to decomposi- 

 tion, is composed of the fecal matter ; the remaining fifth is made 

 principally of the slops of tl'e kitchen, the waste matter of breweries, 

 the offal of slaughter-houses, the fluid from stables, and the organic 

 matter that becomes mixed with the street dirt. 



"We will now endeavor to arrive, as near as possible, at the chemical 

 ingredients of this sewage as it enters the sewers, and before any 

 fermentation or decomposition may be supposed to have taken place. 

 In doing so, I shall quote considerably from the highly interesting 

 report of the royal commissioners appointed in 1868 to inquire into 

 the best means of preventing the pollution of the rivers. This report 

 was published in 1870, and. contains an amount of useful information 

 that should, recommend it to the careful perusal of all who may be 

 desirous of investigating the workings of the sewage system. In 

 cities where water-closets are introduced, they estimate about 100,000 

 pounds of sewage to each person per annum, of which the fecal 

 matter of one person forms but a small part. As a matter of 

 course, the constituents of this fecal matter differ very much accord- 

 ing to the customary diet. In a country where much meat is eaten 

 the nitrogenous and phosphorous compounds will be found to pre- 

 dominate to a greater extent than is the case where a vegetable diet 

 prevails. The consequence has been that authors differ very mate- 

 rially in regard to the component parts of this mass. 



The commissioners above referred to have accepted the statement 

 of Roder and Eickhorn, based upon the researches of Wolff and 

 Lehmann, which is, taking the average of men, women, and children, 

 about 850 pounds per annum, containing nearly eight pounds of 

 organic nitrogen. Thudichum made an estimate in 1863, the result 

 of which was that he found the amount of ammonia to be 15.9 pounds. 

 Liebig's estimate is about 600 pounds of fecal matter, containing 

 nearly seventeen pounds of nitrogen. Dr. Kyi, of Cologne, has lately 

 investigated this matter very closely, and although I have not yet 

 seen his statement published, I will give it as communicated to me. 

 He found that he could place the average daily product at two pounds ; 

 and, from a series of analyses, that he could place the amount of nitro- 

 gen at 1.5 per cent. This would make an annual product of 730 

 pounds, containing 10.95 pounds of nitrogen. As this appears to be 



