SEWER-GAS. 9 



having made a series of careful experiments, assisted by B. W. Thomas, 

 President of the State Microscopical Society, and in the presence of 

 O. C. De Wolf, M. D., Commissioner of Health for that city, they 

 have given it as their concurrent opinion that, as at present con- 

 structed, water-traps do not prevent the passage of " disease-germs " 

 into our houses. Dr. De Wolf takes pains to especially emphasize the 

 fact of "the readiness with which organic germs pass through the 

 water of a sewer-trap and are thrown off from the free surface into 

 the atmosphere of a room." (See " Report of the Health Department, 

 City of Chicago, April 15, 1881.") 



But, although I can not speak as an expert in this matter, it will be 

 permitted me to say that there seems no reason, even if other and con- 

 flicting experiments had not been made, why the experiments of Car- 

 michael should be regarded as conclusive. That unwholesome gases 

 did not pass through well-sealed and ventilated traps, at a certain time 

 and under certain circumstances, in sufficient quantity to imperil life, 

 and that organic germs were excluded wholly, furnishes no conclusive 

 evidence that they might not pass through at another time and under 

 other circumstances. The amount of vapor, ah', and gas contained in 

 the sewers is greater at one time than at another. Their elasticity and 

 tendency to escape are varied according to the nature and amount of 

 the gases generated ; according to the temperature, which is changed 

 continually where pipes are in use by the alternate flow of hot and cold 

 water ; and according as the gases are moved upward with more or 

 less force by the direction and strength of the aerial currents through 

 the drains. In our own city, and in other maritime cities, and upon 

 the sea-coast generally, the action of the tides in obstructing the 

 outflow, and thus driving the contents of the sewers back toward the 

 houses where the pipes terminate, is often enormous, and such as, by 

 the most ample provision for escape through ventilators, can not al- 

 ways prevent a sudden pressure upon the water-traps sufficient to dis- 

 place their contents, or to force the gas through the water in the form 

 of bubbles, or, finally, to increase the capacity of the water to receive 

 the sewer-gas by absorption. 



Muhlenberg says, " The bacillus typhi has been found in drinking- 

 water " ; and Dr. Janeway, addressing the Academy, said : 



Another point is the possibility that much of the typhoid fever does not come 

 from breathing sewer-gas, but from drinking water containing the germs of dis- 

 ease, which have been drawn up into the water-pipes and are taken into the ali- 

 mentary canal. In a case under my observation several children were sick in a 

 large house. I turned the water on below, and then, turning it on above, the 

 air was sucked into the pipes below. These faucets were over some drain-pipes 

 connecting with closets where diphtheritic stools had been deposited, and the 

 water above, which was subsequently drunk, was thus tainted. This occurs also 

 where there is no trap, or where there is no direct communication with the 

 sewer. In one institution over seventy children were taken with typhoid fever 

 from this cause. 



