Sundry Notes. 



the Mersey and Irwell standard — the mixture will, 

 in all probability, be putrescible upon incubation. 

 (2) That an added quantity of nitric nitrogen (up to 

 0"3 part per 100,000) to a dilute sewage of the 

 Mersey and Irwell albuminoid nitrogen standard for 

 effluents may not be sufficient to prevent this putres- 

 cence upon incubation, although on the other hand 

 it may. (See Part II., pages 322 and 323.) 



Surface 

 Street Waehlngrs. 



Seven samples were examined — 

 viz., two from Aldershot Camp, 

 one from Rugby, and four from 

 South Norwood. Three of the samples contained so 

 little organic matter that they withstood the incuba- 

 tor test, but the others did not ; of those four others 

 two might be classed as dilute sewages, the remain- 

 ing two being weaker. Although the above samples 

 were few in number, they show, at all events : (1) 

 That even when a street water is comparatively pure 

 organically it requires settlement for grit, and (2) 

 that even after long - continued rain street surface 



waters may be very impure. It has been perhaps 

 too readily assumed in the past that the storm liquid 

 resulting from the adoption of the separate system 

 is relatively unobjectionable. From the bacterio- 

 logical point of view this liquid may be grossly and 

 dangerously (potentially speaking) impure. 



" The few samples of subsoil 

 Subsoil Water, water collected in the neighbour- 

 hood of some of the sewage farms 

 were usually found to be pure, both chemically and 

 bacteriologically ; but this, of course, must not be 

 regarded as proving that wells sunk in such situa- 

 tions are safe for domestic use, or free from serious 

 objection. Two years' work by one of us on the 

 chemical and biological qualities of the Chichester 

 well waters showed that shallow wells sunk in 

 polluted soil and subsoil may show, on searching 

 bacteriological examination, unequivocal evidence of 

 excremental, and, therefore, potentially dangerous, 

 pollution." (Part I., page 105.) 



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