By means of the propelling charge and the grinding effect
of the bullets, this powder was pulverised on explosion.
The irritation caused was not very intense, lasted only a short,
time and affected only a limited area and therefore it was of no
importance in the field, but the initial step had been taken.
Liquid irritants soon came to the front--xylyl bromide
and xylylene dibromide--a mixture used later under the name
of T. stuff, bromo-acetone and brominated methyl ethyl ketone,
later introduced under the name of B. stuff and Bn. stuff."

During experiments they gave such improved results in intensity,
in power of lasting and of affecting an increased area,
that practical results in the field were ensured.
The use of these liquids in projectiles, however, was contrary
to the accepted idea with regard to artillery, according to which
liquid materials should not be used for ballistic reasons.
Specially arranged shoots were required to prove that the projectiles
in use in the German Army could also be used from the ballistic
point of view when filled with liquids.

In this way the first effective German gas projectile, the T. shell
for heavy field howitzers, was evolved (January, 1915).

Early German Gas Shell.--The first important use of German gas
in shell was that of brominated and chlorinated organic compounds,
T. and K. stuffs. Schwarte's book tells us "the use of these
projectiles was continually hampered by lack of understanding
on the part of the troops which it was difficult to overcome.
In the summer of 1915 it was practically in the Argonne alone that
any considerable results were attained by the new projectiles."