CLAYS OF NEW YORK Y73 



HOLLOW BRICK, TEERA GOTTA LUMBER,, FIRE- 



PROOEmO. 



Tlie first term is generally applied to large hollow bricks of 

 more or less rectangular shape, having cross partitions. They are 

 made either of brick clay or semi-fire clay, the latter being the 

 better if protection against fire is desired. The term terra cotta 

 lumber is specially applied to bricks of this class made of a mix- 

 ture of clay and sawdust, so that in burning the sawdust burns 

 out, leaving the body of the ware porous. 



The shape of these bricks is quite variable, and can best be 

 judged by reference to plate 103. They are used for the construc- 

 tion of floor arches, partitions, flue linings, and for wrapping 

 around steel beams and girders. They are also used at times as 

 foundation blocks in buildings, in which case, the brick are salt 

 glazed to prevent absorption, if the body of it is not vitrified. 

 One of the purposes of these bricks is to combine lightness and 

 strength, in addition the hollow spaces serve as nonconductors 

 of heat. 



When used for fireproofing purposes, the product should be 

 such that it will resist any heat to which it might be exposed in 

 case of fire, and when heated it should be able to withstand a 

 stream of cold water without splitting off or cracking. It is for 

 the latter reason that hollow bricks used for fireproofing should 

 be made from a semi-fire clay, and should not be. vitrified. 



Hollow brick are manufactured at a number of places in ]^ew 

 York state ; the material used is in some cases shale, in other cases 

 clay. They are molded in the same kind of press as sewer pipe. 

 Reference to plate 102 will show the style of die employed. 



