who wear the masks,
for nothing like the right kind of breathing can be done. In fact, a
diver at the bottom of the sea has better and more pure air to breathe
than a soldier in the open wearing a gas mask.

It was the first experience of Blake and his chums with the German gas,
though they had heard much about it, and it needed but the first whiff
to make them realize their danger.

Even as Private Drew called to them, and as they saw him running toward
them and trying to adjust his own mask, they were overcome. As though
shot, they fell to the ground, their eyes smarting and burning, their
throats and nostrils seeming to be pinched in giant fingers, and their
hearts laboring.

One moment they had been operating their cameras. The next they were
bowled over.

"Put on your----" began Blake; and then he could say no more. He tried
not to breathe as he fumbled at his belt to loosen his mask. He buried
his nose deep in the cool earth, but such is the nature of this gas that
it seeks the lowest level. There is no getting away from it save by
going up.

In a smoke-filled room a fireman may find a stratum of cool, and
comparatively fresh, air at the bottom near the floor. This is because
cold air is heavier than the hot and smoke-filled atmosphere. But this
does not hold with the German gas.

And so, before Blake could slip over his head the chemical-impregnated
cloth, he lost consciousness. In another moment his two companions were
also unconscious. Private Drew, struggling against the terrible
pressure on his lungs, managed to get his helmet over his head, and then
he gave his attention to his friends.

He knew that to save their lives he must get their helmets on; for a few
breaths of the gas will not kill. But they will disable a person for
some time, and a little longer breathing of it means a horrible death.

And so, working at top speed, the soldier, now himself protected from
the fumes, though he had breathed more of them than he liked, labored to
save his friends.

Suddenly a new terror developed, for, wearing their own helmets which
made them look like horrible monsters out of a nightmare, the Germans
charged against the French and Americans, whom they hoped to find
disabled by the gas.

"Here they come with blood in their eyes if I could only see it!" mused
Private Drew, as he finished fastening the helmet on Charles Anderson,
having already thus protected Joe and Blake. All three boys were now
uncons