These phials were used in the Second World War for training ARP
wardens, firemen, ambulance men and other civil defence workers. Each
test tube contained a very small amount of a different poison gas,
including lethal ones such as Phosgene and Chlorine and merely very
unpleasant ones like Mustard Gas. The tubes were passed around so
that each worker could have a sniff at it and learn to recognise all
of the different gases that the Germans might drop.
Each gas had different treatments and precautions, and it was important
to know which was which. The phials were supposed to contain only
a very safe amount of gas, but the label warns that 'Delicate persons
with bad lungs or respiratory weakness must be cautious. The quantity
of substance applied is so small that serious casualties cannot occur.'