hY TftE ekesidEni:. 
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come it must unless a true spirit of patriotism realises and avoids 
the evil. Be that as it may, the incidence of the laws of nature, 
fortunately, cannot be avoided. The sulliage of sullied water is 
sooner or later burnt out of the water by the burning power of 
the air always being absorbed by such water, or with which the 
water comes into contact during its flow towards the sea or in the 
sea itself. From the sea, as already stated, the water is lifted into 
the air as cloud, and is carried hack by winds again to fall in full 
abundance at the very feet of man. 
The gregarious tendencies of human beings not only involve 
difficulty as regards the getting of plenty of pure water and the 
getting rid of that water when sullied, hut also as regards the 
getting of abundance of pure air and the getting rid of that air 
when sullied. And the larger the aggregation of people, the greater 
the difficulty. A human being in breathing renders a certain and 
rather large amount of air impure every moment of his life. Every 
scoopful of coal burned in a grate, every pound of burning candles, 
every pint of oil consumed in a lamp, every cubic foot of burning 
gas, renders impure a corresponding and very large amount of air. 
This impure air passes up and away into the atmosphere, some¬ 
times under the laws of heat which harness and rein the wind, and 
always under the laws of diffusion. Fortunately the largest city 
is not yet so large as to interfere with impure air exhaled from 
throats and chimneys getting away sufficiently fast, and pure 
air taking its place sufficiently fast, to maintain millions of 
inhabitants in a fair state of health. The trouble rather is, at 
present, that owing to imperfections in the construction of fire¬ 
grates and furnaces, the gaseous product of the combustion of all 
fuel is accompanied by sooty, oily, and other fog-forming inter¬ 
mediate products. For this evil let us hope that art will sooner 
or later furnish a complete remedy. Nature furnishes the remedy 
against the accumulation of impure gas in the atmosphere generally ; 
for the impurity which would be poison and death to the animal 
kingdom is food and life to the vegetable kingdom, and thus is the 
atmosphere kept always in a normal health-giving condition. 
Another, and, as regards preservation of health from attack 
of infectious disease, more serious source of contamination of the 
air of towns, is to be found in the gratuitous delivery of foul 
vapours from certain of the gratings at our very feet as we walk 
along our streets and roads. Now this subject is in several senses 
unsavoury, but it is one that affects the health of ourselves and 
the health and perhaps lives of our children. Therefore no apology 
is offered for its introduction. Indeed it is time that the public, 
