CLAYS OF NEW YORK 6Y9 



three or four chambers before conducting it off to the stack, for 

 the reason that the hot air collects moisture from the bricks in 

 those chambers which are being heated up, and if not drawn off 

 when nearly saturated, and before it has cooled down too much, it 

 will begin to deposit moisture and soften the green bricks. 



Each chamber has a capacity of 20,000 to 22,000 brick. When 

 the partitions between are permanent they are of brick, but the 

 temporary ones are built of heavy paper. 



The manner of firing varies. In the original kiln not only did 

 it take place through doors at the bottom, but coal slack was also 

 fed into the kiln through openings in the top. Many manufac- 

 turers no longer pursue the method of top firing. 



In ISTew York state continuous kilns are used for burning com- 

 mon and paving brick. 



Sorting 



After the bricks are burned they have in every case to be care- 

 fully sorted, for no kiln produces 100^ of bricks which are alike. 

 The product of a kiln of common building brick is usually sorted 

 into stock, hard, rough hard, salmon or pale. 



In burning a kiln of pressed brick, while the percentage of 

 properly burned ones is very much larger than in the case of com- 

 mon brick, still there is often a considerable range in the intensity 

 of the color, and therefore pressed brick have always to be carefully 

 sorted according to the shade. There are numerous shades and 

 colors which the manufacturer is able to produce with any clay or 

 mixture of clays that he is in the habit of using, but in addition, 

 always, a certain number of bricks are of off shades, or show other 

 blemishes due to improper firing; and these are generally sold at 

 much lower rates. 



Efflorescence on bricks 



It is a well known fact that many bricks develop a white coat 

 either during the drying and burning or after the brick have been 

 set in the wall. The popular term for this white coating or efilor- 



