106 



BRICKWORK. 



FIRE-BRICKS, ETC. 



The parts of furnaces exposed to heat are built of bricks made of a descrip- 

 tion of clay which is to different extents infusible, the qualities chosen for use 

 being regulated by the degree of heat to which they are to be exposed. They 

 are known in commerce by the names of Bristol, Stourbridge, Newcastle, 

 Welsh, and Windsor bricks. The first of these are composed almost entirely 

 of silex, and are infusible at the greatest heat of the blast-furnace ; but they 

 are very costly, and seldom used. The second quality are made from clay found 

 in the neighbourhood of Stourbridge, lying in a stratum of considerable thick- 

 ness between the upper soil and the coal-formations ; they are used in the 

 construction of furnaces required to resist great heat, such as those for smelt- 

 ing iron-ores, glass-making, etc., and sometimes for the linings of retort- 

 ovens : for this latter purpose I consider them too expensive, except for the 

 arch immediately over the furnace, as the heat is not intense. The third 

 variety are composed of the clay lying above the coal-measures in Northum- 

 berland, and for the construction of retort-furnaces and ovens are the most 

 desirable. This will not be generally admitted, perhaps, but I am well con- 

 vinced of the fact ; it is useless to employ a brick which costs nearly double 

 the price, when these will serve equally well ; Stourbridge bricks are 150s. per 

 thousand, and Newcastle bricks are 95s. per thousand. All parts of the ovens 

 may be built of Newcastle brick except the arch above-mentioned. Welsh 

 bricks were until lately used for the parts less exposed to heat, because they 

 were the cheapest; now, however, Newcastle bricks are less by 10s. per 

 thousand. Welsh bricks are liable to " honeycomb" when heated, owing to 

 the admixture of inferior clay and extraneous matter. The Windsor bricks 

 made at the village of Hedgesley are good, and bear the same price as New- 

 castle. Fire-lumps are made in various shapes and of different sizes, and 

 may be obtained to suit any purpose of oven-work if ordered ; those kept on 

 stock vary from 4 to 6 inches thick, and from 12 to 36 inches long. Fire- 

 tiles are made from 1^ to 3 inches thick, and from 9 to 24 inches long : their 

 application has already been explained. 



In setting these bricks, etc., care must be taken to use the same clay as 

 that of which the brick is composed, and to have the joint close ; for this 

 purpose the clay must be well " tempered" with little water, and the brick 

 or lump well bedded. If the lump is of large dimensions, a " maul" should 



