Crystals or white crystalline powder.

Transparent and colourless in crystalline form – rather like ice.

Crystallises in the isometric system, usually in the form of cubes.

Soluble in water (35.6g/100g at 0°C and 39.2g/100g at 100°).

Slightly soluble in alcohol, but insoluble in concentrated hydrochloric acid.

Melts at 801°C and begins to vaporize at temperatures just slightly above this boiling point 1,413°C.

Hardness of 2.5 on the MOH scale of hardness.

Specific gravity of 2.165.

Non-combustible – low toxicity.

Hygroscopic – absorbs moisture from damp atmospheres above 75 per cent relative humidity – below this, it will dry out.

solid salt cannot conduct electricity, but liquid and solution of salts can.