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under chemico-physical laws, certain products of animal and 
vegetable decay which, doubtless, are or may be harmful to persons 
drinking the water. No sooner, however, are these impurities 
dissolved, than nature, under chemical laws, begins to burn them 
up by the air dissolved in the water; and before the water has 
flowed far over or into the ground, it again has become hygienically 
pure, that is to say, entirely free from anything injurious to health. 
The slightest recognition by man of the working of the laws just 
mentioned would prevent him adding animal or vegetable im¬ 
purities to water at the very moment of all others when nature 
has brought pure water to the actual dwelling he occupies. Tut, 
alas! man is ignorant of such laws, and ignorant is he likely to 
remain until some of his teachers, under an enlightened view of 
nature’s laws and their origin, weekly preach those laws into his 
ears. A comparatively few yards of porous soil free from actual 
clefts will convert into hygienically pure water all the impurities 
cast out of a dwelling-house. There is not the slightest reason, 
except what is born of excusable—at present excusable-ignorance, 
or inexcusable carelessness, why the well-water of more or less 
isolated rural or suburban dwellings should be contaminated by 
household drainage or by any similar collections of impurities. 
Such refuse should be distributed properly instead of improperly 
in the adjacent ground, and then there would be no risk of the 
well being contaminated. 
How to obtain a proper supply of fresh air to our dwellings, in 
quantity neither too large nor too small, and in temperature neither 
too high nor too low, is an extremely difficult question. This 
difficulty is not due to want of knowledge of the laws governing 
the matter. The laws of heat are ever at work, and also can be 
invoked artificially, to provide displacement of impure air by pure 
air, and the laws of diffusion of gases are ever at work providing 
for the removal of used-up or tainted air. The difficulty chiefly 
consists in our inability to apply our knowledge under ever-varying 
conditions. Take even the case of an isolated dwelling, standing 
within two or three acres or more of ground, where the external 
air is pure, and occupied and owned by a man who has the means 
and the will wherewith to obtain a proper supply of that fresh air 
for his household. The capacity of any given room does not vary; 
practically it always holds the same volume of air. But the 
persons who respire the air in that room may vary in number from 
two or three to twenty or thirty. The air in the room requires to 
be changed ten times as often for twenty or thirty as for two or 
three persons. What mechanical system of ventilation without 
