forward, and looking at a distant point of light through the dim goggles.  We are alone in these deadly fumes, the instructor is not here, there is a tense silence, and all about us is the poison of death.  Oh, what was that fourth point that I was to remember?  Why has the guide turned back?  I thought we were to go out at the further end, where last week the poor fellow fell who lifted his helmet a moment too soon after he got out and caught one whiff which sent him to the hospital, but instead we seem to be turning around and going back.  But there is no time for explanations or questions now; we just plod on through the darkness and soon we are out in the sunlight again—­safe!—­in God’s pure air.  Oh, why did man ever want to pollute it and poison his brother with these deadly fumes of hell!

As a special favor, the instructor allows us, without a mask, to take one swift look into the fumes as we hold our breath.  That yellow green chlorine will corrode the lungs and fill them with pus and blood.  The phosgene is much more deadly and will strike the man down with sudden failure of the heart.

We were also sent through a chamber of the invisible “tear gas,” without a mask.  The object of this is to take away the fear of the gas from the men.  This particular gas has no effect upon the lungs, but sends a stinging pain through the eyes, so that one weeps blindly for some minutes and could not possibly see to shoot or to defend himself.

We are now ready to return to another lecture with more understanding.  No wonder these tired boys under the heavy, hot steel helmets, which absorb the heat of the scorching sun, are listening with all their ears, yet one or two fall asleep for very weariness and may again be caught napping by the enemy’s poison gas up the line.  The instructor is in dead earnest, for the life of every man during the coming conflict may depend upon his message.  His words are still in my ears, for they were strangely like a sermon: 

“Men, I am going to tell you the truth about this deadly gas and you must believe it, for your life will depend upon it.  It can kill and no doubt about it.  But for every poison of the enemy there’s an antidote and we have found it.  Your helmet is perfect and you simply must believe in it, you must trust to it.  We have made full provision for your safety.  If you go under it will be your own fault from one of four causes—­unbelief, disobedience, carelessness, or fear.  If you carelessly go without your helmet it means death.  During an attack, after putting on the respirator, just stand and wait.  There is nothing you can do for yourself except to keep your helmet on.  Your skill, your strength are nothing.  Now if you are caught in an attack unawares remember if you’re still alive at all, there’s hope.  Don’t lose courage.  If your confidence goes, you lose ninety per cent of your defense, for the sole hope of the enemy in gas is surprise and panic.  If you are gassed, don’t move.  Keep still, keep warm, don’t worry, and wait.  To move or try to save yourself will be fatal.