Microhic Life in Sewer Air. 205 



usually of an ethereal or gaseous character ; and being so they 

 are endowed with the attributes which belong to gases, each 

 atom having a repulsive action toward every one of its own 

 kind. These odours are more or less rapidly oxidized when dis- 

 charged into the air. They do not act injuriously upon human 

 beings, except so far as they may take away the ozone or free oxygen 

 in the atmosphere, and render the air less vivifying than it other- 

 wise would be, and they cover up other and more dangerous smells. 

 The odours from individuals are also distinctive. Some 

 individuals smell very disagreeably ; but the mere smell is 

 not capable of reproducing its kind any more than those from 

 flowers and chemical decompositions, and is not, therefore, 

 disease-producing. It cannot set up disease in other peoj)le. 

 The odours from recently-discharged excreta are allied to this 

 class. They are gaseous, have a tendency to diffuse themselves 

 into space, are rapidly oxidized, and are not in any way Phoenix- 

 like — that is, do not grow another generation of a similar kind. 

 True, there are individuals with peculiar idiosyncrasies (as they 

 are called) who cannot bear the smell of musk, or other penetra- 

 ting odours. I have known one lady who could not stay in a 

 room with a blossoming plumbago without feeling faint, though 

 I could not detect any smell from the flower. But these are not 

 cases in point. Stinks of this character may seriously aflect a 

 person, but there is no reproductive power in the smell. It is 

 this point upon which I wish particularly to dwell, so as to 

 bring before you the facts and the nature of so-called sewer gas. 

 The smell of a recently used water-closet is very objectionable, 

 but there is no probability of mischief to the next user on that 

 account. It is no more injurious than is rose-water or the 

 kennel of a fox. Fortunate for humanity that it is so. The 

 odours from recent excreta are like to musk ; they are ethereal, 

 and tend to diffuse themselves, and so to become oxidized, and 

 are rapidly destroyed. The excreta from a cholera or fever 

 patient at its immediate discharge is perfectly harmless ; but it 

 is highly charged with ova, or germs of organic living matter, 

 which are not so harmless. They are not volatile nor diffusible, 

 like the ethereal smells of musk or of the fox. They require to 

 be separated from the containing liquid, dried, lifted, and dis- 

 persed by currents of air. Where so carried they may or may 

 not fall into congenial soils. Any one walking upon the chalk 

 downs on a midsummer day may see the analogue of that which 

 takes place in sewers. The air blowing over the South Downs 

 lifts up the seeds of the various thistles which grow there, and 

 carries them on to arable fields below, or out to sea. In the one 

 case they reach a congenial soil and grow, to the vexation of the 

 agriculturist ; in the other they are destroyed. So it is with 

 disease germs from sewers. 



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