128 OP FERTILIZERS. 



fever, which, if the sufferer be not relieved by removal to 

 perfectly pure air, may end fatally.* Carbonic acid when 

 breathed in the proportion of 15 to 20 parts in 1,000 of 

 air, causes immediate distress and feelings of .suffocation, 

 accompanied often with giddiness and headache. This is 

 sometimes followed by a slight delirium and then by an 

 irresistible desire to sleep.* If breathed in still larger 

 quantities it not unfrequently causes death. The fumes 

 of smoking charcoal, in a close room, have often been 

 fatal to people sleeping in the room. 



404. The effects, if breathed in smaller proportions, are 

 dulness, heaviness, difficulty of thought, and apparent 

 stupidity. The extreme sleepiness and dulness sometimes 

 observed in children who have remained several hours in 

 an ill- ventilated school-room, are, doubtless, often caused 

 by the carbonic acid in the air of the room. 



This comes from the breath of the occupants of the room, 

 and sometimes from the fire-place or stove. Ammonia, 

 breathed when very strong, immediately takes away the 

 breath. When weaker, it irritates the lungs, and, even 

 when very weak, if breathed for a considerable time, it 

 produces symptoms of typhoid fever. 



405. These poisonous gases are generated in drains 

 and sink-holes, in heaps of dirt of any kind, in dam]) 

 cellars and close rooms, in dirty ditches, in muddy 

 puddles, swamps and undrained marshes, and wherever 

 water is allowed to remain stagnant. 



These poisons show their presence by rendering the air 

 disagreeable to the sense of smell. Whatever is offensive 

 to this sense is more or less dangerous ; and, if foul air, 

 that is, bad smelling, foetid air, be breathed, it is always 



* Dr. Taylor, as quoted bv Dr. John Bell. Third National Sanitary Conven 

 tion, p. 425. 



