4 SEWAGE AND ITS PURIFICATION 



ing the tap the liquid is forced up into the barrel without 

 effluvium or exposure to air. 



In London, cesspools were in general use till 1847 '■> there- 

 after water-closets with a sewerage system discharging directly 

 into the Thames, until later (1865-1875), when intercepting 

 sewers with storage tanks, discharging on the ebb-tide only, 

 were constructed on the north and south banks of the river. 

 In Paris it was not till 1884 that a law was passed ordering the 

 discharge of all sewage directly into the sewers, and the abolition 

 of all fixed or movable cesspools. 



In 1854 the first British General Board of Health reported 

 that it was far less injurious to the public health to have the 

 refuse of towns in water in the next river than underneath or 

 amidst dwellings.^ 



For many reasons it was necessary to organize a regular 

 system of drainage by sewers. But the difficulty was still not 

 overcome. In the ramifications of these canals a good deal of 

 leakage occurred. The construction of traps to intercept the 

 gases, and of ventilators to remove them, was for a long time, 

 and in many parts still continues to be, very imperfect ; in fact, 

 the ventilation question is only now showing signs of solution. 

 The greatest difficulty, however, arose when an outlet had to be 

 found for the immense volume of the sewage of modern towns. 

 To discharge it untreated into rivers, unless of many times the 

 capacity of the sewage and well oxygenated, converted the 

 stream itself into an open sewer. It will be in the memory 

 of many Londoners how black and offensive the Thames was 

 formerly between the bridges, and even in 1894 the Seine near 

 Paris was so polluted that Dr. Billings observed " bubbles of 

 gas from the putrefying slime at the bottom escaped from the 

 dark surface, and no fish could live in it," affording an example 

 of a bacterial process working naturally, but imperfectly, and 

 under improper conditions. The Irwell, at Manchester, in 1892, 

 was practically sewage, as the following analysis by Hepworth 

 Collins^ will show : Total solids, i6o'6 ; consisting of organic, 

 59*6 ; mineral, loi'o ; suspended solids, 29*6 ; ammonia free and 

 albuminoid, 0*900; chlorine, 11*9; oxygen absorbed, 4*90. 



The danger of sewage mud-banks is well shown by an 

 example from America. In 1899, after a channel had been 



^ A historical summary of the official inquiries in England is given by Mr. 

 Adrian, Assistant-Secretary to the Local Government Board, in the Interim 

 Report of the Royal Commission on Sewage, 1902 : Miuutes of Evidence. 



2 Transactions of the Sanitary Institute, 1892, p. 196. 



