Eric Scerri

found for many of mercury’s uses, in measurement instruments, valves, switches and dental amalgams. However, other applications such as in energy-saving compact fluorescent bulbs are increasing demand for the element.

Chromium was discovered in 1798 by French chemist Louis-Nicolas Vauquelin, who ground up precious stones in an effort to explain their colours, and later discovered the element beryllium in the same way

Chromium alloyed with iron makes stainless steel, which does not oxidize or rust.

Because charcoal is used to extract iron from its ore, what you get is inevitably steel instead of pure, softer iron.

Steel is iron mixed with a little carbon, which makes it harder.

Iron colours the surface of Mars, the ‘red planet’,

One of the remaining uses of lead is in car batteries. Invented in 1859, the lead-acid battery is relatively cheap and can deliver the high current needed to start an engine. When the battery discharges, electrodes immersed in sulphuric acid are converted to lead sulfate. Charging reverses the process. If the lead sulphate rests for too long, it begins to form crystals, and recharging becomes difficult – this is why it is important to maintain the charge.