SEWER-GAS. 11 



to settling of the walls, floors, and fixtures. Sometimes, also, large 

 holes are made in the traps or leaden pipes by rats. I have in my 

 possession examples of all these varieties of defective traps, taken 

 from some of the best houses in this city, and the existence of which 

 defects was not suspected until disclosed by the plumber. The traps, 

 to be effective, it is unnecessary to say, must be kept in perfect work- 

 ing order, for this is a dangerous door to be left ajar, even for one 



moment. 



The complete protection of our houses against sewer-gas will not, 

 however, be accomplished when a trap shall be invented which shall 

 be liable to no accidents and shall never fail. The trap is a matter of 

 small consideration compared with the whole amount of plumbing 

 work, of which it constitutes only a fraction. 



The Pipes. Professor Doremus demonstrated at the Academy that 

 gases would pass readily through brick and stone, and through un- 

 glazed earthenware, even, in one instance, against a resisting pressure 

 of two and a half feet of water, and in another against the pressure of 

 a column of mercury thirty inches in height. The experience of every 

 practical plumber confirms these experiments. Gases escape more or 

 less readily, also, through iron pipes. 



Lead and iron pipes are subject to the erosive action of the gases, 

 and of various reagents. They are also, like the traps, liable to be 

 broken by the settling of walls, floors, and fixtures, and they are occa- 

 sionally broken by their own weight. The leaden pipes may be eaten 

 by rats ; at the jointings, they are believed occasionally to be perfo- 

 rated by galvanic action. In nearly all these cases the holes are at 

 first small, but frequently a large number of these small holes will be 

 found at the same time in different portions of the plumbing. These 

 are the minute perforations to which Dr. Billings probably referred 

 when he said, " there is more danger from a pin-hole in a pipe than 

 from the traps " ; for, while it is true that a large proportion of the 

 germs perish for want of a favorable soil, it is equally true that one 

 germ of a malignant type, conveyed into a system fully prepared for 

 its nutrition, is as fatal as a thousand. Colin estimates that one bac- 

 terial rod, under favorable circumstances, will produce 281,500,000,000 

 in forty-eight hours ; and that, were it not for the unfavorable cir- 

 cumstances incident to its situation, it would fill the ocean in five 

 days. It is not impossible that this one " pin-hole " might admit the 

 typical bacterium into a typical soil. 



Mr. Charles F. Wingate, sanitary engineer, says : 



Even the best plumbing will not last for ever, but needs attention. Leaks 

 may occur to permit the admission of sewer-gas from drain-pipes due to defect- 

 ive castings, or to walls settling in houses built on made ground, or from the 

 strain of the alternate expansion and contraction from hot water, or even from 

 the forcing of lead joints by the pressure of steam discharged froja manufacto- 

 ries into the public sewer. 



