CLAY WORKING INDUSTRIES. 233 



the full heat of the furnace and never cool until the furnace is shut down 

 for repairs. 



The manufacture of glass in tank furnaces has turned a part of the 

 energy of the glass pot men into a new channel. Glass tanks are large 

 iron tanks lined with special shaped blocks of the finest refractory 

 materials and are covered by an arched brick roof, under which the flames 

 from the furnace circulate. Very few tank furnaces are built alike and 

 consequently each one necessitates a complete set of moulds, for every 

 block and brick required. 



A tank is usually constructed by contract, the manufacturer agreeing 

 to make the blocks and erect the brick work. Great stress is laid on a 

 perfect fit of the blocks, as the glass is sure to search out any cracks or 

 fissures in the retaining walls. 



Blocks for tank furnaces are of various sizes. Some of them weigh 

 eight or ten hundred pounds. To dry and burn such enormous lumps 

 of clay, is a matter of great difficulty. Time is the main feature and 

 must be used without stint. 



The refractory material trade of Ohio is now situated in two districts. 

 The Scioto district, including the factories at Portsmouth, Sciotoville, 

 Webster, Ironton and Oak Hill forms the principal center of production. 

 This district depends mainly on the fine flint clays of Scioto county, 

 Ohio, and Carter county, Kentucky, just across the Ohio river. 



The Ohio Valley from Steubenville to Wellsville is the source of a 

 large brick and sewer-pipe industry. The bricks however are sold 

 indiscriminately as fire brick and pavers. The factories on the Ohio side 

 of the river are mainly in the fire brick business. The factories on the 

 West Virginia side of the river are in the paving brick business, and 

 only make fire brick incidentally. These works all use one stratum 

 of hard fire clay which however, readily becomes plastic when ground 

 and tempered. The balance of the fire-brick manufacture in the state is 

 conducted in isolated shops at Youngstown, Niles, Cleveland, Dover, 

 Mineral Point, Zanesville, Logan and a few other towns. No statistics 

 were collected or are available from other sources. 



V. THE MANUFACTURE OF BUILDING MATERIAL. 



The manufacture of building material made from clay really includes 

 the following lines of production: 



fl. Common hand made brick. 

 2. Soft mud brick. 



I 5. Pressed brick. 

 1^6. Enameled brick. 

 Terra cotta. — Building ornaments. 



r 1. Eire proofing. 



Hollow goods. < 2. Chimney and flue linings. 



(_ 3. Building and foundation blocks. 



{1. Roofing tiles. 



2. Glazed panel tiles. 



3. Encaustic floor tiles. 



