...boil in (partial) vacuo are known as vacuum-pans (which see). Some drive off a part of the aqeous fluid, and are called condensers, such as the Degrand. See condenser. A set of kettles in Louisiana consists of five, placed in line, and with their tops on the same level. Underneath is a furnace, the mouth of which is outside the building. The kettles are technically known as the grande, prop...