ohibited by the Hague rules. But the Germans were not
playing the game according to the rules, so the British soldiers were
strangled in their own trenches and fell easy victims to the advancing
foe. Within half an hour after the gas was turned on 80 per cent. of the
opposing troops were knocked out. The Canadians, with wet handkerchiefs
over their faces, closed in to stop the gap, but if the Germans had been
prepared for such success they could have cleared the way to the coast.
But after such trials the Germans stopped the use of free chlorine and
began the preparation of more poisonous gases. In some way that may not
be revealed till the secret history of the war is published, the British
Intelligence Department obtained a copy of the lecture notes of the
instructions to the German staff giving details of the new system of gas
warfare to be started in December. Among the compounds named was
phosgene, a gas so lethal that one part in ten thousand of air may be
fatal. The antidote for it is hexamethylene tetramine. This is not
something the soldier--or anybody else--is accustomed to carry around
with him, but the British having had a chance to cram up in advance on
the stolen lecture notes were ready with gas helmets soaked in the
reagent with the long name.

The Germans rejoiced when gas bombs took the place of bayonets because
this was a field in which intelligence counted for more than brute
force and in which therefore they expected to be supreme. As usual they
were right in their major premise but wrong in their conclusion, owing
to the egoism of their implicit minor premise. It does indeed give the
advantage to skill and science, but the Germans were beaten at their own
game, for by the end of the war the United States was able to turn out
toxic gases at a rate of 200 tons a day, while the output of Germany or
England was only about 30 tons. A gas plant was started at Edgewood,
Maryland, in November, 1917. By March it was filling shell and before
the war put a stop to its activities in the fall it was producing
1,300,000 pounds of chlorine, 1,000,000 pounds of chlorpicrin, 1,300,000
pounds of phosgene and 700,000 pounds of mustard gas a month.

Chlorine, the first gas used, is unpleasantly familiar to every one who
has entered a chemical laboratory or who has smelled the breath of
bleaching powder. It is a greenish-yellow gas made from common salt. The
Germans employed it at Ypres by laying cylinders of the lique