ATMOSPHERE IN RELATION TO HUMAN LIFE AND HEALTH. 249 



LOCAL GASEOUS IMPURITIES — SULPHURETED HYDROGEN — SEWER AND DRAIN AIR. 



When certain animal and vegetable matter undergoes decay, the 

 small quantity of sulphur which it contains combines with hydrogen 

 and forms the gas, sulphureted hydrogen, which, even in mere traces, 

 is very offensive to the sense of smell. It also forms some offensive 

 organic sulphides. The sulphureted hydrogen gas set free often bears 

 with it germs of disease, so that it has been treated as a danger signal. 

 Drain or sewer air, however, does not always contain the gas in appre- 

 ciable amount, when dangerous germs are being given off, and the 

 faint smell of an old filth deposit may exceed in morbific effects the 

 unpleasant odor of fresh putrefactive processes. Nor does sewer air, 

 even if it be poisonous, often contain virulent germs of disease. Dogs 

 and horses are rapidly prostrated by 1.25 to 4 A^olumes of sulphureted 

 hydrogen per 1,000 of air, but men can breathe a larger quantity. In 

 large doses, nausea, headache, convulsions; in small doses, low febrile 

 symptoms follow its inhalation. The frequent inhalation of small doses 

 produces chronic poisoning; 1 per cent is at once destructive of life. 



The air over some of the most pestilential marshes in Italy contains 

 an unusually large quantity of the gas. In mines it produces convul- 

 sive, narcotic, and tetanic symptoms. 



SULPHUROUS ACID. 



Sulphurous acid in the air of cotton and worsted manufactories appar- 

 ently tends to produce bronchitis and anaemia. It destroys vegetation 

 in the neighborhood of copper works. 



CARBURETED HYDROGEN. 



Carbureted hydrogen, breathed in small quantities, as in the air of 

 some mines, does not seem to cause ill effects, and experiment has 

 shown that for a short time it can be breathed in the proportion of one 

 volume to four of air. 



HYDROCHLORIC ACID. 



Hydrochloric acid vapor is very irritating to the lungs. In some 

 processes of making steel this gas, with sulphurous and nitrous acids 

 and chlorine, cause bronchitis, pneumonia, destruction of lung tissue, 

 and eye diseases among the workers. It destroys vegetation for a long 

 distance when given off in large quantities from manufactories. 



CARBON BISULPHIDE. 



Carbon bisulphide vapor, given off in vulcanized india-rubber facto- 

 ries, produces, in those exposed to it, headache, giddiness, pains in the 

 limbs, nervous depression or excitement, and complete loss of appetite. 



Carbon monoxide is a very poisonous gas arising from the consump- 

 tion of coal, coke, coal gas, and especially charcoal. Less than 0.5 per 

 cent is fatal to animals. Fatal consequences from the use of charcoal 

 stoves where ventilation is defective are common in some countries. 



