e
water; it is useful in keeping it free from contamination, although
water allowed to stand in copper receptacles for a period of from
twenty-four to forty-eight hours at room temperature would be
effectively sterilized, no matter what its contamination and no matter
how much matter it held in suspension. But in order to insure such
results the copper must be kept thoroughly clean. This polishing is
not, as was popularly supposed, to protect the consumer from "copper
poisoning," but to prevent the metal from becoming so coated with
foreign substances that there is no contact of the copper with the
water, hence no antiseptic quality.

Dr. Henry Kreamer, of Philadelphia, proved that within four hours
typhoid germs were completely destroyed by the introduction into the
polluted water of copper foil.

"Granting the efficiency of the boiling of water for domestic
purposes, I believe that the copper-treated water is more natural and
more healthful.... The intestinal bacteria, like colon and typhoid,
are completely destroyed by placing clean copper foil in the water
containing them.

"Pending the introduction of the copper treatment of water on a large
scale, the householder may avail himself of a method for the
purification of drinking water by the use of strips of copper foil
about three and one-half inches square to each quart of water, this
being allowed to stand overnight, or from six to eight hours at the
ordinary temperature, and then the water drawn off or the copper foil
removed."

Although a splendid antiseptic, copper in weak solution is not
harmful, no more so than the old copper utensils used by our
forefathers were harmful. Undoubtedly they were of benefit, and the
use of them prevented the growth of typhoid and other bacteria. People
of to-day might well go back to copper receptacles for drinking
water.

FOOTNOTES:

[1] For published reports of the work, see Bulletins 64 and 76, Bureau
of Plant Industry, U. S. Department of Agriculture; reports prepared
by Dr. George T. Moore and his assistant, Mr. Karl F. Kellerman.

[2] See Bulletin No. 76, supra.

CHAPTER IV

=Ridding Stagnant Water of Mosquitoes=

Because of the serious and often fatal injury it inflicts on man, the
most dangerous animal known is the mosquito. Compared with the evil
done by the insect pest, the cobra's death toll is small. This
venomous serpent is found only in hot countries, particularly in
India, while mosquitoes