QI: Quite interesting facts about glass Molten glass solidifies so quickly that its molecules don't have time to settle into a regular crystalline lattice. This is because glass contains small amounts of soda (sodium carbonate) and lime (calcium oxide) that interfere with the structure of the silica (silicon dioxide) atoms as they cool. Without these additions, the silica would cool more slowly. This would form chemically neat and regular - but much less useful - quartz. So it is glass's chaotic structure that makes it smooth and transparent. Invention of glass The earliest known glass artefacts are Egyptian and date back to 1350BC, but it was the Romans who first produced transparent glass, as it enabled them to admire the colour of their wine. Because the ancient Chinese preferred tea to wine, they had little use for glass, which tends to break when heated unevenly. They devised a fine white ceramic ware made from white kaolin, which they vitrified (made slightly "glasslike") with feldspar. Westerners dubbed this porcelain because of its alleged resemblance to the shell of a cowrie (or porcellana, little pig). An early ersatz Western version of porcelain, pâte tendre or soft paste, was made with ground glass instead of feldspar. For almost 500 years, from the end of the 14th century until the 19th, no glass was made in China at all. Now, though, it is the world's largest producer, controlling 34 per cent of the global market. Venetian glass The Venetian island of Murano is still the centre of Venice's glassmaking industry. The glass furnaces of Venice were moved to the island in 1291, to reduce the risk of their setting fire to the city. Here, inspired by migrant Islamic craftsmen, Venetians learnt to make the finest glass in the world, giving them a monopoly that lasted for centuries. Smart glass The invention of spectacles towards the end of the 13th century added at least 15 years to the academic and scientific careers of men whose work depended on reading. In the 17th century, the philosopher Baruch Spinoza made his living as a lens-grinder; this enabled him to do his philosophy independently of patronage, but may have led to his early death from a lung illness in 1677. Glass mirrors are said to have been used by Filippo Brunelleschi in his experiments to establish the laws of perspective - a discovery which had a huge impact on Renaissance painting. Glass beakers and test tubes transformed ancient alchemy into the modern science of chemistry. The microscope and the telescope, invented within a few years of each other at the end of the 16th century, opened up two new universes: the very distant and the very small. The power of glass By the 17th century, European glass had become cheap enough for ordinary people to use it for windowpanes. This not only protected them from the elements, but also flooded their houses with light, initiating a great leap forward in hygiene. Dirt and vermin became visible, and living spaces clean and disease free. Partly as a result, plague was eliminated from most of Europe by the early 18th century. In the mid-19th century, easily sterilised swan-necked glass flasks allowed the French chemist Louis Pasteur to disprove the theory that germs spontaneously generated from putrefying matter. This led to a revolution in the understanding of disease. Soon afterwards, glass light bulbs changed work and leisure utterly; at the turn of the 20th century, new lamination techniques made glass tougher and safer than ever before. Glass king Charles VI of France (1368-1422) had recurrent hallucinations that he was made of glass and had to carry pieces of iron in his clothing to protect himself. He was known variously as Charles the Mad and Charles the Well-Beloved. An expanded fully updated version of the QI App for iPad and iPhone is available now at theqiapp.com at £2.99 Next week: QI swims with whales