i 



Microbic Life 171 Sewer Air. 213 



passage from one person to another be exposed to the air for 

 more than a small fraction of a second, the corpuscle dies, and 

 the patient, though at first reviving, afterward succumbs to the 

 mischief produced by the dead fibrine. If growing germs are 

 exposed to a current of fresh air, free from ammonia, and with 

 its fair proportion of oxygen, in the sewers, the germs will be 

 deprived of vitality before they escape into the open air. It is 

 for this reason that the ventilation of sewers must be complete if 

 such ventilation is to be safe. A partial ventilation does not 

 provide for the death of the living, growing germ, and it is this 

 living, growing germ which does the mischief ; for the other 

 form, the resting spore, will not rise from the watery bed. The 

 growing germ is also destroyed by sulphuretted hydrogen and its 

 binary compounds, the product of the decomposition of all 

 albuminous matters. I say, then, that well-ventilated sewers 

 are safe ; they are doubly so if they are thoroughly and properly 

 flushed. If they are not sewers of deposit they cannot produce 

 sewer gas, and if they tlioroughly stink, disease germs cannot 

 live in them, so that in either case there is no danger ; but there 

 is a possible danger, when it is not discoverable by reason of 

 smell, if those openings which give out offensive odours are 

 occasionally free from the discharge of stinking matter, and 

 some one who is not germ-proof stoops down at the opening. 

 Children will be victims. In a pure atmosphere the life of the 

 germ is momentary, and all serious danger is soon at an 

 end. I have said in a pure atmosphere. If the air is impure, 

 if it contains alkaline gas in the form of ammonia rather than 

 the nitrous or sulphurous form of gases, there is the possibility 

 of a much longer life for the germ than when the air is pure, 

 or has an acid reaction. It is due to this fact that diseases 

 spread in unventilated, dirty houses, and if it was not for the 

 sulphurous acid which is found in the London smoke-fogs, it is 

 most likely that the life-history of disease germs would be made 

 more manifest than it is when we have an atmosphere entirely 

 without ozone for days together. 



We may take it as true that living disease germs from sewer 

 ventilators are possible factors, but they are rarely provided. If 

 the sewers are only partially ventilated, with tendency to the 

 formation of carbonic acid in excess, there is a mould formation 

 rather than bacterial life, and moulds are not vet proved to 

 be zymotic disease germs to human beings. They are com- 

 paratively benign ; like benign bacteria, they help to purify 

 both air and water, and return the albuminoid or nitrogenous 

 matters to their simple elements, ready for use by the vegetable 

 world. 



I cannot conceive benign organisms becoming malignant in 

 the processes which take place in sewers unless the temperature 



