186 ANNUAL OF SCIENTIFIC DISCOVERT. 



water polluted with 5 per cent, of sewage, we are led in each case 

 to the inevitable conclusion that the oxidation of the organic mat- 

 ter in sewage proceeds with extreme slowness even when the 

 sewage is mixed with a large volume of unpolluted water, and 

 that it is impossible to say how far such water must .flow before 

 the sewage matter becomes thoroughly oxidized. It will be safe 

 to infer, however, from the above 'results, that there is no river 

 in the United Kingdom long enough to effect the destruction of 

 sewage by oxidation." 



The pollutions of the rivers by sewage and by various sorts of 

 manufacturing refuse is thoroughly discussed, as are also the 

 various remedial expedients that have from time to time been 

 proposed, and, in conclusion, a strong expression is given in 

 favor of the system of irrigation where practicable, at least as 

 far as the sewage of towns is concerned. " Manufacturers, also, 

 will generalty find the land the best recipient of their waste prod- 

 ucts. The spent liquors from tan-yards may thus be completely 

 turned to agricultural use. Some of the foul liquids from wool- 

 washing will also be a serviceable addition to sewage used in 

 irrigation. As to other polluting materials, those from calico- 

 print and silk works, for example, which plants cannot assimi- 

 late, manufacturers will have to resort to subsidence or filtration ; 

 and individual cases will doubtless be met with in which want of 

 available land will impose serious difficulties in the way of effi- 

 cient purification ; it is therefore proper to add that, in any enact- 

 ment on the subject, ample time should be allowed to those who 

 are earnestly endeavoring to abate any nuisance with which they 

 are chargeable." 



The Commissioners conclude with the recommendations that the 

 casting of any solid matters, of whatever kind, into rivers and 

 running waters, as well as the discharge of any polluting liquids 

 into any river or stream, be forbidden by law, and that all the 

 rivers and streams in England be placed under the superintend- 

 ence of a central authority or board (whose duties are defined), 

 who shall be qualified to deal with all questions connected with 

 .the pollution of water and the water supply. 



Having in view, at present, only the chief sources of pollution in 

 the basins of the Mersey and Ribble, and the methods of cleansing 

 now available, they suggest that the following liquids be deemed 

 polluting and inadmissible into any stream : 



" (.) Any liquid containing, in suspension, more than 3 parts 

 by weight of dry mineral matter, or 1 part by weight of dry 

 organic matter, in 100,000 parts by weight of the liquid. 



" (&.) Any liquid containing, in solution, more than 2 parts by 

 weight of organic carbon, or 0.3 part by weight of organic nitro- 

 gen, in 100,000 parts by weight. 



" (c.) Any liquid which shall exhibit by daylight a distinct 

 color, when a stratum of it 1 inch deep is placed in a white porce- 

 lain or earthen-ware vessel. 



" (<i.) Any liquid which contains, in solution, in 100,000 parts 

 by weight, more than 2 parts by weight of any metal except cal- 

 cium, magnesium, potassium, and sodium. 



