Note 193 — XVI. CONCERNING TURKEY.[190]

According to Beckman, the ancients were not acquainted with real alum. He says it was discovered by the orientals, who established works in the thirteenth century in Syria (apparently at Rukka or Rochha, east of Aleppo, whence the name of Roch-alum, still in use). The best now comes from the neighbourhood of Civita Vecchia. The method of manufacture in England and Scotland is to mix broken alum slate with fuel, and to set it on fire. When combustion is over the residual mixture is lixiviated with water; a solution of the earthy salt being obtained, potash salts are added, and crystals of alum are the result. (Penny Cyclop. and Macculloch’s Comm. Dict.)