Salt - “Think of the love that you eat when you salt your meat”.
These are the closing phrases of the song Sodium Chloride composed by the American singing sisters Kate & Anna McGarrigle. Their song describes how a little atom of chlorine, wandering around in the sea, meets an atom of sodium; by exchanging one single electron from the sodium to the chlorine atom, they become sodium chloride. We call this compound table salt, or just salt.
Abundantly present on Earth, salt has always played through history a crucial role: from money to most used food preservative. And of course, it is the raw material we make chlorine from.
In salt, the sodium carries a positive charge (Na+) and the chlorine a negative one (Cl-). We call these ions. The alternation chlorine and sodium ions are arranged in a perfect cubic pattern and the bonds are strong. It takes heating to over 800°C to melt salt. But in water it dissolves easily.
For thousands of years, salt has been used as a food preservative. There is evidence of its use as early as 6050 BC. One of the oldest verifiable salt works was the Xiechi Lake in China, at least 6000 years BC. In ancient Egyptian tombs salt was found among the funeral offerings together with salted birds and fish. In Africa, the Touareg have maintained traditional routes across the Sahara for the transportation of salt. And in the first millennium BC, Celtic communities traded salt and salted meat to the ancient Greek and Romans in exchange for wine and luxury goods.
In the chlorine industry, salt is one of the three raw materials, together with water and electricity. In Europe, the sector uses about 15 million tonnes of salt per year.
Salt is one of the most abundant minerals on Earth. It is estimated that the reserves of solid rock salt are 3.7x1018 tonnes (that is 3.7,000,000,000,000,000,000 tonnes!) and even 5x1025 tonnes of salt dissolved in the oceans and salt lakes. As such, salt can be considered as an inexhaustible raw material for the production of chlorine.
From salad to salary
The word salad literally means salted. It comes from the ancient Roman practice of salting leaf vegetables. And the word salary is derived from the Latin word salarium: this was the money paid to the Roman army soldiers for the purchase of salt.
> Read and view more
• The Wikipedia pages on salt are particularly detailed
• Watch and hear the beautiful song Sodium Chloride
• View the lyrics of this song
• Read how salt is won in a salt mine (on Euro Chlor website)