Scheele discovered chlorine in 1774 by the action of HCl on MnO2.
The gaseous element itself was first produced in 1774 by Carl Wilhelm Scheele at Uppsala, Sweden, by heating hydrochloric acid with the mineral pyrolusite, naturally occurring manganese dioxide, MnO2. Humphry Davy investigated it in 1807 and eventually concluded that it was a simple substance but truly an element. He announced this in 1810, yet it took another ten years for some chemists to accept that chlorine really was an element finally.
- Chlorine kills bacteria – it is a disinfectant.
- It is used as an oxidising agent and in substitution reactions.
- Chlorine gas is itself very poisonous and was used as a chemical weapon during the First World War.