SEWER GAS AND ITS DANGER TO HEALTH. 573 



de rinined. Still more difficult is it to find by chemical analysis the 

 proportion of ner g"es of decay. 



In well ventilate and well flushed sewers, Dr. Russell, jf Glasgow, found 

 the following ratio : 



20.70 vols, of oxygen in 100 vols, of air. 

 78.79 vols of nitrogen in 100 vols, of air, 

 0.51 vols, of carbonic dioxide in 100 vols, of air. 

 No sulphuretted hydrogen in 100 vols, of air. 

 Traces of ammonia in 100 vols, of air. 



Carbonic oxide is present only in excessively minute quantities, and even then it 

 may have entered the sewer or drain through leakage of illuminating gas from 

 gas mains. 



In the absence of more satisfactory methods of analysis, it is usual with 

 chemists to determine the amount of pollution of the air, or the organic matter in 

 it, by determining the amount of .carbonic dioxide present, assuming that there is 

 a certain fixed proportion between the amount of carbonic dioxide and the organic 

 matter. ^ Thus, Prof. W. Ripley Nichols records as the average of many care- 

 fully conducted experiments in Boston, the amount of carbonic dioxide in a 

 sewer in-'that city as follows : 



The average of 

 31 determinations in January, 1878, was 8.7 vols, of CO2 in 10,000 vols, of air. 

 44 determinations in February, 1878, was 8.2 vols, of CO^ in 10,000 vols, of air. 

 47 determinations in March, 1878, was 11. 5 vols, of CO.2 in 10,000 vols, of air. 

 12 determinations in April, 1878, was 10.7 vols, of CO^ in 10,000 vols, of air. 

 8 determinations in June, 1878, was 27.5 vols, of CO2 in 10,000 vols, of air. 

 8 determinations in July, 1878 was 211.9 vols, of CO2 in 10,000 vols, of air. 



6 determinations in August, 1878, was 23.9 vols, of CO2 in 10,000 vols, of air. 



7 determinations in January, 1879, was 8.0 vols, of CO^ in 10,000 vols, of air. 

 14 determinations in February, 1879, was 11. 6 vols, of CO2 in 10,000 vols, of 



air. 

 20 determinations in March, 1879, was 11.8 vols, of CO.^ in 10,000 vols, of air. 



He remarks: " It appears from these examinations that in such a sewer as 

 the one Berkeley Street, which, being of necessity tide-locked, is an example of 

 the worst t)'pe of construction, the air does not differ from the normal standard 

 as much as many, no doubt, suppose. In a general way, as we have seen, there 

 is a larger amount of variation from normal air during the warmer season of the 

 year ; but even when the amount of carbonic acid was largest, it was only ex- 

 tremely seldom that sulphuretted hydrogen could be detected." >i< * * 

 -" I think that it should be said that the soil pipes and house drains are much 

 more likely causes of discomfort and danger than the sewers." 



Hence the importance of a thorough ventilation of all the soil, waste and 

 drain pipes in a building. 



1 Such is strictly tr e only for a r fouled by respi ation, while it may not give accurate results in other 

 •cases. 



In regard to this interesting question I must refer to the Rf port of Prof. Ira Remsen on the subject ot 

 orgai.ic matter in ihe air, published in the National Board of Healih Bulletin, Vol. II No. 11. 



