For many, the word ‘chlorine’ enters their vocabulary poolside on a hot summer day. Peering out of irritated, bloodshot eyes and with a peculiar chemical smell we can’t get out of our nostrils, we learn of this element’s antimicrobial prowess. At the molecular level, chlorine interacts with organic matter - a cell’s internal working bits to be more precise - creating new compounds none of which help in the function of life. It’s as if the germs were mowed down with a flamethrower. Those sensitive eyes and airways are the result of perhaps tens of millions of your own cells screaming in pain as they die. Woops. Well, a little collateral damage on the war on germs is a fair price to pay, right?

It is such a cheap and effective disinfectant that it’s used in most public water systems in the developed world and why diseases like cholera and typhoid sound like something quaint that bedevilled peoples of yesteryear.

At room temperature chlorine is a faint yellow gas. Captured in a two inch long vial the color is easy to see. Breaking the ampule guaranteed to bring back childhood memories.