bursts with such suddenness as to give no time for taking cover. Its
moral effect exceeds the material in the trenches, but it is deadly
along roads or in the open. Gas shells have a peculiar sound, all
their own, difficult to describe but never forgotten when once heard.
It has been described as a "rumbling" noise, but I think "gurgling" is
better. (It's a pity some one can not take a phonograph into the lines
and "can" some of these things.) When gas shells land they do not make
much noise, having a very small bursting charge; merely sufficient to
break the case which contains the gas in liquid form. They are often
mistaken, by new troops, for "duds" or "blinds," as we call shells
which fail to explode. As soon as the liquid gas is liberated,
however, it vaporizes and quickly spreads over a considerable area.
There are many kinds, but they can generally be distinguished by the
smell. Some are merely lachrymatory or "tear" shells; the gas
affecting the eyes in such a manner as to produce constant "weeping"
and consequent inability to see clearly. Others, however, are deadly
and one good breath will put a man out of action and a couple of
"lungfuls" will usually kill him.

[Illustration: British Machine Gun Squad Using Gas Masks]

About this time, I think it was December 19th, 1915, we had our first
experience with chlorine gas or "cloud gas" as distinguished from
"shell gas." The troops on our immediate left got a pretty bad dose,
but, owing to the peculiar formation of the lines and varying air
currents, we did not suffer severely from it. The lines in the Ypres
salient were so crooked that the enemy rarely attempted to use this
form of gas after the first big attack in April, 1915, as it would
frequently roll back upon his own troops. Shell gas was constantly
used, generally being fired against our positions in the rear;
artillery emplacements and such. Being well equipped with gas masks
or respirators, we suffered little harm from it.

Christmas, 1915, was a quiet day on our front, both sides being
apparently willing to "lay off" for a day. There was no firing of any
kind and both our men and the enemy exposed themselves with impunity.
Aside from this, however, it was the same as any other day. There was
none of the visiting and fraternizing of which we heard so much on the
previous Christmas. The Germans opposite us had a number of musical
instruments and on that night and on New Year's Eve they almost sang
th