THE MANUFACTURE OF BUILDING BRICK. 219 



The general variation in the physical characters of New Jersey 

 common-brick clays can be seen from the following table: 



Table shozving physical characteristics of New Jersey brick clays. 



LOCALITY shn ^ k Fire shrinkage Fire shrinkage Color when^f^. *£*$* 



LOLALllt. age per at cone .05. at cone 1. burned. lb Y o!r sa in 



cent. ' v 4.- • 



Kinkora, 7- •••• 5-6 Buff 168 



Cliffwood, 6.5 1.5 3- Red 88 



Matawan, 6.3 1. 3.7 Red 197 



Bordentown, 8.8 8.2 11.8 Red 251 



Toms River, 4.3 2.3 Red 68 



Somerville, 5.0 6.6 Red 297 



Herbertsville, 2.5 0.5 1.5 Red 49 



Yorktown, 7.6 1. 2.8 Red 229 



Flemington, 3. 1.6 7.6 Red 159 



Buckshutem, 7. 3.3 6. Red 291 



The above figures refer to laboratory tests made on the raw 

 clay. In the case of some, such as the clay from Bordentown, it 

 will be seen that both the air and fire shrinkage are high, and too 

 great, in fact, to permit their being used alone. It is, therefore, 

 necessary to mix some sandy clay with them. 



Common-brick clays vary widely in their composition, but most 

 of them contain a rather high percentage of fluxing impurities. 



The following table gives the maximum, minimum and average 

 percentage of the different constituents in a brick clay, compiled 

 from a number of analyses 1 : 



Chemical Composition of Common-brick Clays. 2 



Constituent. Range. Average. 



Silica, 34.35 -90.877% 49-27% 



Alumina, 22.14 -44-00% 22.774% 



Ferric oxide, 0.126-33.12% 5-3 T i% 



Lime, 0.024-15.38% 1.513% 



Magnesia, 0.02 - 7.29% 1.052% 



Alkalies, 0.17 -15.32% 2.768% 



Water, 0.05 -13.60% 5-749% 



Moisture, 0.17-9.64% 2.502% 



1 H. Ries, The Clays of New York, Bull. N. Y. State Museum, No. 35, p. 

 639. 



2 The lime and magnesia of this table represent new calculations, and, hence, 

 differ from the original. 



