322 



Professor Frank Clowes 



[MaTcli 9, 



The 13-foot bed has for long periods given a purification from 

 dissolved oxidisable matter of over 60 per cent. It has maintained 

 a most satisfactory state of aeration, since the air drawn from the 

 bottom has contained, on an average, 17 per cent, of oxygen. 



About 60 per cent, of the matter which settles from the sewage 

 under ordinary conditions is combustible, and could, therefore, very 

 well be dealt with by a destructor. 



The tendency of the coke bacteria beds is undoubtedly to improve 

 in their purifying power with age, provided they are not overworked. 

 A bed which had given for some time a 50 per cent, purification, 

 gradually increased in efficiency until its purifying effect reached 

 nearly 70 per cent, The effluent from this bed underwent an 

 additional purification of 20 per cent, by treatment in a second 

 similar bed. 



The effluent from a single coke-bed worked on the intermittent 

 principle was clear and odourless, and remained in this condition 

 when it was kept in open or closed bottles in a warm laboratory. It 

 maintained the life of gold-fish, roach, dace, and pike indefinitely : it 

 was therefore not only well aerated, but was able to maintain its 

 aerated condition. This proves that it was free from any rapidly 

 oxidisable matter. It was undoubtedly, however, undergoing a 

 gradually further purification by the action of the bacteria which it 

 contained, and with the assistance of dissolved oxygen. Such an 

 effluent would be quite suitable for introduction into the tidal part 

 of the river, where the water is too salt and muddy to be used for 

 drinking purposes. 



Bacteria are present in large numbers in the river-water itself, 

 and undoubtedly exert a most useful purifying effect upon the water 

 during its flow. The relation between the number present in the 

 sewage and in the water of the Eiver Thames, below and above 

 locks, is shown by the following estimations made by Dr. Houston. 

 The number of liquefying bacteria included in the total number of 

 bacteria present in one cubic centimetre, and the number of spores 

 of bacteria, are also stated : — 



