SYNTHESES IN HISTORY

The blown glass industry is evidently a very late addition to human skills, because objects made of this material can be found in tombs only after the end of the first century AD

It was Egyptian craftsmen who first discovered ways of colouring glass and used their invention to fabricate a lucid substance that could give the illusion of being a precious stone. And it fell to priests, above all, to make green glasses in imitation of emeralds which they did as early as the second millennium BC

Strabo (1st century. BC) affirmed that Pharaoh Ramses Sesostris (17th century BC) had a large statue cast in fake emerald that was still being admired at Constantinople in the days of Theodosius...

Blue glasses imitating turquoise were the earliest to be made, but towards the year 1400 BC it proved possible also to make glasses of various other colours: violet, light blue, orange yellows and, more rarely, milky shades and black.

The Phoenicians were great competitors of the Egyptians in this field. The glass works of Sidon (Pliny) and Tyre (Strabo and Theophrastus) enjoyed great fame, but their colouring materials were metallic (iron, cobalt and nickel). It would seem that the stones were never ground, but works in a pasty state.

The Greeks, too, were familiar with this art. In his dialogue "Timeus", for example, Plato mentions a vitreous paste, the so-called "cast stone", that imitated natural precious stones.

But the art was not known in either Syria or Mesopotamia, and even less so in China.

The Chinese imported coloured glasses from the Roman Empire. A Chinese work entitled Wei-Lo (221-264 AD) enumerates ten colours of glasses that came from this source.

Synthesising techniques did not undergo any profound or substantial changes in Roman glassworks, and this remained the case until the chemistry underlying this industry took real steps forward as a result of the intervention of the Arabs.

It was only in medieval times that the art of synthesis came to be comprised in the vast body of the science of alchemy, which was an expression of the desire to obtain new and precious substances by the manipulation of base matter.

This period saw many tractates about the fabrication of artificial stones.

Above all, however, mention should here be made of two famous scientists of the Renaissance period: Imperati Ferrante (1642) and G. B. Porta (1677). The latter published a book entitled "Natural Magic".