THE MANUFACTURE OF BUILDING BRICK. 241 



anthracite in part. With coal, the fuel is sometimes placed on 

 grate bars, or on the floor of the hearth. 



Continuous kilns. — These were originally designed to utilize 

 the waste heat from burning. Many types have appeared, some 

 of which are patented, but the principle of all is the same. It 

 consists essentially in having a series of chambers, arranged in a 

 line, circle or oval, and connected with each other and also- with 

 a central stack by means of flues. Each chamber holds about 

 22,000 bricks. In starting the kiln, a chamber full of bricks is first 

 fired by means of exterior fire boxes, and while the water-smoke 

 or steam is passing off, the vapors are conducted to the stack, but 

 as soon as this ceases the heat from the chamber first fired is con- 

 ducted through several other chambers ahead of it, before it finally 

 passes to the stack. In this manner the waste heat from any 

 chamber is used to heat the others. When any one compartment 

 becomes red hot, fuel in the form of coal slack is added through 

 small openings in the roof, which are kept covered by iron caps. 



As soon as one chamber has reached its maximum temperature, 

 the next two or three ahead of it are being heated up while those 

 behind it are cooling down. A wave of maximum temperature is 

 therefore continually passing around the kiln. It is thus possible 

 to be burning brick in certain chambers, filling others, and empty- 

 ing still others, all at the same time, making the process a con- 

 tinuous one. Continuous kilns are employed in many States for 

 burning common brick, and with considerable success, but only 

 three are in use in New Jersey, and none of these are employed in 

 burning building brick. 



16 ci, G 



