CHAPTER XIIL 



HOLLOW WARE FOR STRUCTURAL 

 WORK AND CONDUITS, 



CONTENTS. 



Hollow ware. 



Character and uses. 



Raw materials. 



Method of manufacture. 



New Jersey industry. 

 Conduits. 



Clays and manufacture. 



New Jersey industry. 



HOLLOW WARE FOR STRUCTURAL WORK. 



Character. — Under this heading are included fireproofing, 

 terra-cotta lumber, hollow blocks and hollow bricks. These are 

 all hollow, being molded through a stiff-mud die (see PI. XXXII, 

 Fig. i ) , and may contain one or more cross webs or partitions to 

 give them strength. Fireproofing is the term applied to those 

 forms used in the construction of floor arches, partitions and wall 

 furring for columns, girders and other purposes in fireproof 

 buildings. Terra-cotta lumber is a form of fireproofing that is 

 soft and porous, owing to the addition of a large percentage of 

 sawdust to the clay. The former burns off in the kiln, -thus leav- 

 ing the material so soft and porous that nails can be driven into it. 

 It is used chiefly for partitions. Hollow blocks are used for ex- 

 terior walls, in both fireproof and nonfireproof buildings. They 

 are of rectangular outline. Hollozv brick are like hollow blocks in 

 form, but no larger than ordinary building bricks. 



A number of different shapes and sizes of fireproofing are 

 made, and while the majority of them agree in being 12 inches 



(277) 



