understood. Individual cures by
surgery and medicine appeal to personal interests, but these are
negligible compared to the prevention of plagues like smallpox, typhus
and tuberculosis. If such diseases had not been successfully combated by
science three out of four of the present civilized population would not
be in existence at all. The organized and intensive application and
developments of science, of preventive medicine, constitute the strictly
neutral work in this war by which all humanity will profit for all time
to come.

In passing it is interesting to note that the great power supplied by
Niagara Falls is being utilized to produce some of the chemical marvels.
One great industry there is making soda by the electrolytic process.
That is, salt brine is pumped from the saline deposits in western New
York and piped to the works. This is run into electric cells and through
these a current of electricity is led. The salt, which is composed of
chlorine and sodium, decomposes under the electric attack. The sodium
goes to one pole and combines with water to form caustic soda, whereas
the chlorine escapes at the other pole. Let us follow the chlorine,
which is a yellowish-green gas, more than twice as heavy as air, and has
found a new use as poison gas in the great war--for which all the world
should be ashamed.

It is collected and compressed to a liquid form and shipped in
containers under pressure for use in chemical works and bleacheries and
for the purification of drinking water. It has been found above all
things effective in destroying noxious bacilli. A surprisingly small
amount of the gas dissolved in the water is enough. In New York city the
water has been chlorinated and no single case of typhoid fever has been
traced to the supply.

CHAPTER XXI.

OUR NEIGHBORING ALLY.

CANADA'S RECRUITING--RAISE 33,000 TROOPS IN TWO MONTHS--FIRST
EXPEDITIONARY FORCE TO CROSS ATLANTIC--BRAVERY AT YPRES AND
LENS--MEETING DIFFICULT PROBLEMS--QUEBEC AROUSED BY CONSCRIPTION.

The world has marvelled at the achievement of Canada at Valcartier camp
near Quebec and the dispatch across the Atlantic Ocean of a fully
equipped expeditionary force of 33,000 men within two months of the
outbreak of war between Great Britain and Germany. But the magnitude of
that feat cannot be appreciated properly until one considers that on
August 4, 1914, Canada had a permanent force of only about 3500 men.

These soldiers, who for the