Class I

are sub-divided into furnaces with a, temporary Chandler's Encyclopedia IMG:content-0192.jpg:[blocks in formation] and ore-heaps, whose walls are fine charcoal, earth, or fine ore, and are pulled down and built up for each operation. Stalls for roasting ores are often built with permanent walls on three sides, while the front is temporary. Furnaces of division b are cla ified into those worked with natural draught and those worked with blast. They are generally in the form of a shalt or chimney, which may be cylindrical, conical, or pyramidal. Lime-kilns, kilns for roasting ores, and small furnaces for reducing lead and tin ores, are worked with the natural draught. England, French furniture was imported. Renai ance moldings and broken shell-shaped woodwork known as Louis Quinze work next became popular, and the fantastic curves called Rococo showed to the best advantage the luster of heavy gilding then so prevalent. Famous designers of artistic furniture were J. A. Mei onnier and Vernis Martin. Later in the 18th cent IMG:content-0193.png:[graphic][merged small] Where blast is used, we have the various kinds of blast-furnaces for smelting iron, copper and lead ores, and the familiar cupola of the iron foundry. When built of two concentric iron shells, between which water circulates freely, such a furnace is said to be water jacketed. It is a frequent practice to water jacket parts of furnaces exposed to intense heat or rapid corrosion.