liquor, distilled only once, was called the spirit of wine or brandy. Purified by another distillation (or several more), this was called spirit of wine rectified. The second distillation was made in [a] balneo mariae and in a glass cucurbit, and the liquor was distilled to about one-half the quantity. This was further rectified as long as the operator thought it necessary to produce brandy. To shorten these several distillations, which were long and troublesome, a chemical instrument was invented that reduced them to a single distillation. A portion was ignited to test the purity of the rectified spirit of wine. The liquor was good if a fire consumed the entire contents without leaving any impurities behind. Another, better test involved putting a little gunpowder in the bottom of the spirit. The liquor was good if the gunpowder could ignite after the spirit was consumed by fire. (Hence the modern "proof" to describe alcohol content.) As most brandies have been distilled from grapes, the regions of the world producing excellent brandies have roughly paralleled those areas producing grapes for viniculture. At the end of the 19th century, the western European markets, including by extension their overseas empires, were dominated by French and Spanish brandies and eastern Europe was dominated by brandies from the Black Sea region, including Bulgaria, the Crimea, and Georgia. In 1884, David Sarajishvili founded a brandy factory in Tbilisi, Georgia, a crossroads for Turkish, Central Asian, and Persian trade routes and a part of the Russian Empire at the time. Technology Except for a few major producers, brandy production and consumption tend to have a regional character, and thus production methods significantly vary. Wine brandy is produced from a variety of grape cultivars. A special selection of cultivars, providing distinct aroma and character, is used for high-quality brandies, while cheaper ones are made from whichever wine is available. Brandy is made from so-called base wine, which significantly differs from regular table wines. It is made from early grapes to achieve higher acid concentration and lower sugar levels. Base wine generally contains smaller amounts (up to 20 mg/L) of sulphur than regular wines, as it creates undesired copper(II) sulfate in reaction with copper in the pot stills. The yeast sediment produced during the fermentation may or may not be kept in the wine, depending on the brandy style. Brandy is distilled from the base wine in two phases.