BACTERIAL PURIFICATION 215 



and interference. A small significant fact is that the discharge 

 from the fine beds at Sutton and Exeter, and I believe in other 

 places, is always, at the first rush, turbid and of inferior quality, 

 as a consequence of disturbance. Dr. Clowes also in the 

 above report remarks on the occasional turbidity of the effluent, 



apparently due in ordinary flow mainly to the presence of 

 rbacteria." 



The want of provision of a separate area for the first stage is 



often concealed by the fact that where the sewers are old, or of 



[great capacity or length, or when the sewage has been stored 



for sedimentation, the first, or even a part of the second, stage 



[.may have actually been passed through before arrival at the 



[,works, so that the liquid may be quite amenable to the third 



;tage of strong aeration, such as is supplied by Lowcock's, 



Waring's, and Ducat's systems. 



A remark in the above report is : " Fish die at once when 

 they are placed in the present effluent produced by chemical 

 precipitation, probably because there is a serious deficiency of 

 dissolved oxygen in the liquid. . . ."^ Various fish "have 

 [lived for months in the first effluent from the coke-beds, and 

 rould apparently live and thrive in this liquid for an indefinite 

 period." 



In a supplementary report by Drs. Clowes and Houston 

 (October 26, 1899), the former finds that the cellulose deposit 

 on the coke containing " some fine coke particles and sand 

 grains, cotton and woollen fibres, and diatoms, but consisting 

 largely of chaff, straw, and woody fibre," caused a diminution 

 of capacity of about i per cent, per week in the 13-foot bed, but 

 that this was reduced to 0*64 per cent, per week by previously 

 sedimenting the sewage in a partitioned wooden trough. The 

 sediment was inoffensive, and contained 52 to 70 per cent, of 

 combustible matter. Dr. Houston found 1,800,000 bacteria 

 per gramme of deposit, not accounting, however, for its amount, 

 as " this number of typhoid bacilli, for example, weigh only 

 o"ooooi47 gramme." The character of the bacteria differ some- 

 what from those in crude sewage. There were more B. enteritidis 

 and fewer coli, Proteus-like germs were abundant, with B, pro- 

 digiosus, arborescenSi and an allied form. From colour tests and 

 inoculations he concluded the probable presence of tubercle 

 bacilli ; in only one case, however, was a fatal effect produced 

 on animals. 



1 See Chapter XIII., and also p. 57. 



