CLAYS OF NEW YORK 785 



Fire brick when, molded are commonly set on the floor to dry 

 for a few hours, after which they are repressed. 



They are then loaded on cars and sent to the drying tunnels. 

 (See description under Drying of bricks, p. 668) The rapidity with 

 which the drying can be carried on depends on the porosity of the 

 clay, its plasticity and the size of the molded object. 



The burning of fire brick is done either in up or down-draft 

 kilns, of either circular or rectangular form. 



Behavior of refractory hrich when heated 

 In some experiments recently made by J. D. Pennock^ to deter- 

 mine the heat conductivity, expansion, and fusibility of refractory 

 brick, bricks made of Grecian magnesite, American magnesitO; 

 silica brick, and coke oven tiling made in Belgium, were used. 



In the charts and detailed figures given by Mr Pennock it is 

 shown that the Grecian magnesite conducts heat the most readily, 

 the American next, then the silica brick, while the coke oven brick 

 is the poorest conductor. The poor conductivity of the coke oven 

 brick is thought to lie in its purity and density. 



Expansion fests of fire hrich 



Expansion ^^^f^f^°^ ' 

 of core P^yf.r'' 

 Inch Inch 



Grecian magnesite 0.07 0.11 



.07 .11 



American magnesite .067 .10 



" 057 .088 



Coke oven tiling 05 . 076 



" 05 .076 ■ 



The expansion test was made by supporting a core of the brick in 

 a horizontal position. One end was against a support and the 

 other against a movable lever. The core was heated by means of 

 burners placed underneath. 



1 Trans. Amer. inst. min. eng., September, 1896. p. 263. 



