ATMOSPHERE IN RELATION TO HUMAN LIFE AND HEALTH. 209 



dividing* walls of cells, to air on both sides. The weight of air inhaled 

 in the course of the day is seven or eight times that of the food eaten. 

 The mechanical work of breathing represents energy expressed by the 

 lifting of 21 tons 1 foot in 21 hours. 1 



From every volume of air inspired about 1J per cent of oxygen is 

 abstracted, and a somewhat smaller quantity of carbonic acid gas is at 

 the same time added to the expired air. 



Experiments on animals show that the amount of oxygen absorbed 

 is very little if at all increased by an excess in the air surrounding 

 them. 



OZONE. 



Ozone is an important constituent of tbe atmosphere, greatly con- 

 tributing to its purity and freshness and to the vigor of human life. 

 It is a form of oxygen in which the molecule is considered to be 

 composed of three molecules of the gas. 



Although existing in small quantity in the air, rarely exceeding 1 

 part in 10,000, the activity of ozone is so great and its function so 

 beneficial that its presence in normal quantity is, in ordinary sur- 

 roundings, a fair guaranty of the purity of the air and of healthy con- 

 ditions so far as breathing is concerned. No ozone is found in the 

 streets of large towns, in most inhabited rooms, near decomposing 

 organic matter, and in confined spaces generally. In very large, well- 

 ventilated rooms it is sometimes, though rarely, detected. Ozone is 

 found in very small quantity a little to leeward of a large town. Even 

 at Brighton, a town of about 110,000 inhabitants, ozone was barely 

 discoverable on the pier when the wind blew from the town, but 

 abundant when the wind was from another direction. 



Ozone has the power of oxidizing to a much higher degree than oxy- 

 gen, and vigorously attacks organic matter in a fine state of division. 

 It is therefore a strong disinfectant. Its oxidizing power is the reason 

 of its absence from confined spaces where organic matter, dust, or smoke 

 is present, for such matter quickly uses up the small portion of ozone 

 which enters with the fresh air. The walls, furniture, etc., are also 

 covered with fine dust, which the ozone attacks. The difference we 

 feel in going from a furnished room, however large, into the open air, 

 is thus partly accounted for. There is somewhat more ozone on moun- 

 tains than on plains, and most of all near the sea. Water is said by 

 Carius to absorb 0.8 of its volume of ozone. An examination of sea 

 water with a view to detect the amount contained in it would be diffi- 

 cult, but might give interesting results. A great excess of ozone is 

 destructive to life, and oxygen containing one two hundred and fortieth 

 part of ozone is rapidly fatal. The ordinary quantity even has bad 

 effects in exacerbating bronchitis and bronchial colds and some other 

 affections of the lungs. 



' Professor Haughton, Carpenter's Principles of Hum an Physiology. 

 SM 95 14 



