From the x-mass issue of the Economist, the best magazine there is: "WHAT is Islam's greatest gift to the world? The faith of the Koran, Muslims will promptly say—along, some would add, with the Arabic language. Yet it may be that the single most pervasive legacy of Islamic civilisation is not holy scripture, but the rather unholy art of distilling alcohol. Not only were Arabs the first to make spirits. The great trading civilisation of Islam spread the skill across the globe, and in its lands some of the world's finest alcoholic concoctions are still made to this day.
Although the delights of fermented drink were known to cavemen, the natural alcohol content of primitive wines and beers would not top 16%. Yet early China and Egypt both discovered techniques of distillation that might, if applied to such brews, have stiffened their potency. Later, Aristotle described a way of vaporising salt water into fresh, the Romans distilled turpentine from pine oil, and two Alexandrian ladies in the first centuries after Christ, Mary the Jewess and Hypatia, invented devices for separating liquids by heating them. Yet, oddly, nobody in the ancient world at this time seems to have exploited the different boiling-points of alcohol and water to concentrate weak wine into stronger spirits (though some historians assert that the Indians made a fortified beer this way, in or around 800BC).
Alcohol
An explanation may lie in the fact that alcohol, when distilled from fermented drinks, typically contains traces of poisonous methanol. Since methanol vaporises at a lower temperature than drinkable ethanol, the trick is to discard the first part of any distillation. Sadly, many prospective tipplers probably perished before the Arabs sorted out the technique. It is possible, too, that the bubbly science was set back some years by the Roman emperor Diocletian, who decreed the burning of alchemists' manuscripts in 296AD for fear their discoveries would debase his coinage.
The book-burning was not entirely successful. Medieval Arab science took up the work of the Greeks, as the word alchemy itself suggests. (It is the Arabic article al- added to the ancient Greek kimia, which referred to the magical science of the black land of Kemet, which is to say Egypt.) Precisely when and by whom the distillation of alcohol was perfected is not known.
Some suggest that Egyptian monks did the deed some time in the sixth century. Others credit the Armenians. There is no conclusive evidence for either theory. What is known is that by the ninth century Arab authors such as Jaber bin Hayyan, an Iraqi polymath best known for elaborating al-jabr or algebra, were describing “flammable vapours” at the mouths of heated wine vessels.
His contemporary, the legendary poet and lush Abu Nawas (who died in 815AD), was less prim. In one ode, versifying over a night of revelry in a Baghdad tavern, he called for increasingly strong drink, ending the session with a liquor that was “as hot between the ribs as a firebrand”. The description clearly hints at something punchier than mere wine....."