282 J. C. BRANNER 



Gaudin as long ago as 1858, should, when low in iron, withstand 

 heat which would fuse all other refractory materials. 



"Bauxite is a compound having a composition intermediate 

 between diaspore and limonite, and consists of hydrate of 

 alumina combined with hydrated oxide of iron. 



"On account of the large quantity of water present this min- 

 eral shrinks greatly on heating, is usually refractory, and, if it 

 does not contain too much iron, when added to fire clays, increases 

 their refractoriness. 



" Siemens used bauxite bricks with 50 per cent, of alumina, 

 35 of iron oxide and 3 to 5 of silica, which lasts five or six times 

 as long as Stourbridge first-brick. Schwarz recommends for 

 crucibles for manufacture of cast steel a composition of one to 

 two parts Goettweiher clay and two parts of burnt bauxite from 

 Wochein. The bricks of the Compagnie Parisienne at the 

 Vienna Exposition withstood the heat of molten platinum, yet 

 their fracture was like that of stoneware." 



Sir William Siemens tested bauxite as a furnace lining and 

 says^ of it: "A series of experiments to form solid lumps by 

 using different binding materials have shown that 3 per cent, of 

 argillaceous clay suffice to bind the bauxite previously calcined. 

 To this mixture about 6 per cent, of plumbago powder is added, 

 which renders the mass practically infusible, because it reduces 

 the peroxide of iron contained in the bauxite to the metallic 

 state. Instead of plastic clay as the binding agent, waterglass 

 or silicate of soda may be used, which has the advantage of 

 setting into a hard mass at such a comparatively low temperature 

 as not to consume the plumbago in the act of burning the brick. 

 A bauxite lining of this description resists both heat and fluid 

 cinder in a very remarkable degree, as I have proved by lining 

 a rotative furnace at my sample steel works at Birmingham, 

 partly with bauxite, and partly with carefully selected plumbago 

 bricks. After a fortnight's working the brick lining was reduced 

 from six inches to less than half an inch ; whereas the bauxite 

 lining was still five inches thick and perfectly compact. It is 



' The scientific works of Sir Wm. Siemens, I., London, 1889, 296. 



