HO USE-DRAIN A GE. 313 



for ornament or luxury ; it varies greatly according to the style 

 of house, the essential point being that it shall furnish the means 

 of getting rid of excreta and of water fouled by domestic use, 

 without danger to the health of the inmates of the house. 



What, then, are the dangers to health from defective plumb- 

 ing ? They are due to gases or to micro-organisms coming from 

 defective fixtures, joints, or pipe, or from soil pollution due to 

 such defects. The gases in question are, for the most part, prod- 

 ucts of the decomposition of organic matter of animal origin, and 

 the types are carbonic acid, ammonia and its compounds, and sul- 

 phureted hydrogen. There are also produced certain effluvia, of 

 the precise nature of which little is known ; the most common is 

 that giving a faint, sweetish, peculiar odor, resembling that of 

 boiled turnips. 



These gases and odors do not produce specific disease, but when 

 they are distinctly present in a house the inmates are liable to be 

 affected with various forms of disturbed digestion, loss of appe- 

 tite, slight headache, and a depressed state of vitality. How 

 far these are due to the gases themselves and how far to the mi- 

 cro-organisms present under such circumstances we do not yet 

 know. The majority of persons gradually become so accustomed 

 to their effects that they can live and work with little or no ap- 

 parent inconvenience in an atmosphere which is so charged with 

 them as to be not only offensive, but really dangerous to those 

 accustomed to pure air only. Plumbers, scavengers, workers in 

 sewers and at sewage-works, or in bone-boiling establishments, 

 etc., prove this ; but it must be remembered that these are sur- 

 vivors, and that a certain number who begin these occupations 

 soon find it necessary to go into some other business. Upon the 

 whole, the dangers from gases only in connection with house- 

 drainage are small, and comparatively easy to avoid, the main 

 thing for this purpose being a complete and constant ventilation 

 of the pipes. 



In part the dangers are due to extremely minute particles of 

 living matter, most if not all of which are vegetable organisms 

 known as bacteria. There are many different kinds of bacteria, 

 and they have very different properties and powers, but those 

 which concern us in this connection are those which grow and 

 multiply in decomposing organic matters, and especially in ex- 

 creta. Almost without exception these bacteria belong to species 

 which are found in the air of streets, in all intestinal discharges, 

 and in all putrefying matters ; they are not only harmless under 

 all ordinary circumstances, but are highly useful in decomposing 

 dead organic matter into simple compounds available for the nu- 

 trition of plants. They are found in countless numbers in the 

 slimy, pulpy layer of decomposing matter lining the interior 



