248 DR. C. A. BURGHARDT ON THE POLLUTION OF 



tions of the amount of free carbon dioxide dissolved in 

 river waters, are valuable indicators of the state of that 

 river as regards organic pollution. 



I consider the Irwell the best possible example of the 

 saturation of a water with the gaseous products of the 

 decomposition of its carbonaceous constituents^ and I am 

 quite certain that it is absolutely necessary to remove at 

 once the large quantity of sewage pollution from the river 

 so that the other organic matters,, which are less easily 

 oxydizedj, may have a chance of being changed and des- 

 troyed by further oxydation. Owing to the rapid falling 

 movement of the river^ from its source above Bacup^ at 

 an altitude of 1300 feet;, to Manchester^ which may be^ on 

 the bed of the river, about 150 feet above the level of the 

 sea, there is a first-rate chance for an ordinary river to 

 purify itself. It will be at once apparent on consulting 

 the Table "C '^ that the Irwell at Bury is half as much 

 polluted as it is at Throstle Nest, in Manchester. Again, 

 on consulting Table '' D/' it will be seen that the Irwell 

 at the Salford Boundary is far purer than the Irwell at 

 Throstle Nest. Making a calculation from the analytical 

 data given in the Table, it appears that the water at 

 Throstle Nest contains 76 per cent, more albuminoid am- 

 monia, and 36 per cent, more oxydizable organic matter 

 than the same water as it arrives at the Salford boundary. 

 How can this tremendous increase in pollution be ac- 

 counted for ? It is almost entirely due to pollution of the 

 Irwell by its tributaries, the Irk and the Medlock, the 

 sewage, being mostly that poured into the rivers by the Man- 

 chester sewers, because the sewage of Salford has been 

 diverted from the Irwell altogether, I believe. On refer- 

 ring to Table " D " it will be seen that the river Medlock 

 is nothing more or less than a filthy sewer. It is a 

 burning disgrace to a civilized community to allow such 



