Mustard gas is actually not a gas but a thick viscous liquid that can remain on the ground for years when conditions are right. The chemical releases a vapour that is either odourless or smells of mustard depending on the purity of the liquid.

Polonium is a silver-grey metallic chemical element that can exist as 33 different species known as isotopes. All 33 isotopes are radioactive. The one that is suspected of killing Arafat is polonium-210, the same isotope that killed the former Russian spy Alexander Litvinenko.

Countless science teachers, textbooks and fans of ice skating will tell you that ice melts under pressure. Unfortunately it is simply not true.

Purple, and variations thereof - mauve, indigo, violet, magenta, crimson and claret - are ubiquitous nowadays. But it was not always so.

Opium poppy extracts and their chemical derivatives were and still are invaluable in relieving the suffering of the wounded. It is therefore safe to say that both the opium poppy and the red poppy, or least the artificial variety, have been employed to bring immense relief to members of the armed forces, albeit in totally different ways.

The provision of safe water is a global challenge today and has been so throughout history, not least during periods of war. And that applies to both civilians and armed forces.