AIE 39 



Air Impurities hy Decomjwsition of Organic Matter.—- 

 The air of sewers has always been regarded with great 

 suspicion, but as a matter of fact exact enquiry shows that 

 in sewers which are well constructed, the air is remarkably 

 pure, and contains very little carbonic acid or sulphuretted 

 hydrogen. Further the organisms present are much the 

 same as in the outside air, both as to number and char- 

 acter, while the men working in well -ventilated sewers are 

 no more unhealthy than the average of the population. 

 These results are the outcome of scientific methods of 

 drainage, and are a tribute to sanitary science. 



When the air of sewers finds its way into inhabited places, 

 which generally occurs through bad construction, the results 

 appear to be very different ; febrile disturbances, sore 

 throat, bowel trouble, and in certain conditions of body — 

 as in lying-in women — actual blood-poisoning. In animals 

 there is evidence to show that this state of atmosphere 

 reduces the normal resistance of the body to the invasion 

 of specific diseases, and renders them not only more 

 susceptible, but aggravates the type of case. 



Sewage farms when properly managed are unobjection- 

 able, but even badly managed farms have not been proved to 

 be productive of disease. It would appear that danger from 

 sewer gas and sewage emanations need only be looked for, 

 when these find their way from ill constructed drains into 

 a closed space, as into badly ventilated stables and houses. 



In badly constructed sewers and drains the contents 

 ferment and putrefy, with the disengagement of many 

 gases, some of which are highly complex, and the majority 

 offensive. There is evidence to show that sewer-gas in this 

 condition may seriously affect those engaged in opening up 

 and clearing out the drains, and there is no difficulty in 

 understanding what such gases are capable of doing even 

 diluted on entering buildings. 



Emanations from manure-pits are not infrequently 

 believed to be heaWnj, even by educated persons. Prob- 

 ably it is the ammonia that reminds them of the stimulating 

 presence of ' smelling salts.' 



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