296 THE SCIENTIFIC PAPERS OF 



It was evident that if iron and steel were to be produced largely 

 by direct process, that process must be a self-acting or mechanical 

 one, and here my attention again reverted to the rotating furnace 

 above-mentioned. If I could succeed in furnishing such a rotating 

 furnace with a lining capable of resisting the high degree of heat 

 requisite for the precipitation of the iron, and at the same time 

 capable of resisting the chemical action, I felt confident that this 

 mode of conducting the process must succeed. My attention here re- 

 verted to M. Le Chatelier's former suggestion of the use of Bauxite, 

 which possesses the requisite qualities, if only it can be put into a 

 compact form and rendered sufficiently infusible. 



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 powder previously calcined. To this 

 mixture about 6 per cent, of plumbago powder is added, which 

 renders the mass practically infusible, because it reduces the per- 

 oxide 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 plum- 

 bago in the act of burning the .brick. When the lining is completed, 

 the interior surface of the bricks is preserved against corrosion 

 by fluid cinder, added to bind them together, which also prevents 

 contact with the flame. 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 6 inches to less than half an 

 inch ; whereas the Bauxite lining was still 5 inches thick and 

 perfectly compact. It is also important to observe that Bauxite 

 when exposed to intense heat is converted into a solid mass of 

 emery of such extreme hardness, that it can hardly be touched 

 by steel tools, and is capable of resisting mechanical as well as 

 the calorific and chemical actions to which it is exposed. The 

 Bauxite used for this lining was of the following composition : 



Alumina .... 53'62 per cent. 

 Peroxide of irou . . . 42'2G 

 Silica . . 4-12 



