The {Necessity of Pure Air for Health. 257 



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no fogs from the large quantities of unconsumed carbon 

 compounds poured forth from millions of chimneys as in 

 London. And we are not much troubled in our houses 

 with foul gases from sewers, so I do not discuss them 

 here. But I wish to draw attention to the air in the 

 lanes and some streets of the towns which can be verified 

 by any one on passing through them, especially on a still 

 night. The air is simply laden with gases resulting from 

 the decay of organic matters of all descriptions which 

 are emptied into the yards, equally from the bedrooms 

 and the kitchen, through the nearest opening. These 

 gases of course penetrate into the sleeping apartments 

 of the neighbouring houses and produce ill effe6ls. 

 The Enteric fever of some of the poorer parts of George- 

 town have been attributed by Dr. FERGUSON to this. 

 This source of impurity should be remedied by the 

 adoption of a proper system of refuse removal. Another 

 source of impurity to the external air is to be found in 

 the emanations from stables and sheds, in which horses 

 and cows are stalled. The air is often loaded with 

 ammoniacal and other gases from the decomposi- 

 tion of the excrement. The ground in some yards is 

 covered with such refuse, and the gases pollute the air for 

 some distance around. This might easily be avoided 

 at all events to some extent by the proper authorities 

 insisting on cows being kept without the town, and on 

 horses' stables being placed in least harmful positions. 

 In inhabited rooms by an arrangement of proper 

 apparatus the air can be filtered and the deposit ex- 

 amined microscopically. This has been done repeatedly 

 with the result of showing the presence of the epithelial 

 scales of the skin, fibres of cloth, cotton, linen, and wool, 



