And he describes how the first elements of the new gas tactics
were developed there.

A Successful Experiment.--The development of the gas shell,
the use of which, generally speaking, is independent of,
but co-ordinated with, wind direction, may have received stimulus
from the fact that the prevailing wind, so important for cloud gas,
favoured the Allies. It is clear that this period was an experimental one,
but we know that by August, 1915, German military opinion had
crystallised out to the extent of formulating certain rules, issued as
Falkenhayn's orders for the employment of gas shell. These early orders
defined two types of shell, one persistent, for harassing purposes,
and the other non-persistent, to be used immediately before an attack.
They specified the number of shell to be used for a given task.
But in this they were unsound and it is clear that the Germans had
an exaggerated opinion of what could be achieved with a small number
of shell. They adhered too closely to high explosive practice.
Various documents reveal the fact that the Germans were much more
satisfied with their gas tactics than they would have been had they
possessed information with regard to our losses from their shell.
They attached insufficient importance to the value of surprise
and highly concentrated shoots, and had a mistaken idea of the actual
specific aggressive value of their early types.

Lachrymators at Loos, 1915.--Germany commenced the manufacture
of lachrymators, crude brominated xylene or brominated ketones, early in,
or perhaps before 1915. These substances caused great inconvenience
through temporary blindness by lachrymation, but were not highly toxic.
In June, 1915, however, they began to produce lethal gas for shell.
Falkenhayn's orders for the use of gas shell, mentioned above,