CLAYS OF NEW YORK 643 



THE BRICKMAXIITG INDUSTRY 



Three kinds of brick are manufactured in New York, common, 

 front and paving brick. 



Common brick. Many works dealing witb clay products state, 

 in an interesting way, what are the requisites of a good common 

 brick, but as a rule few conform to the requirements laid down. 



Most common brick are fairly regular in shape, but here the 

 similarity to one another ends. They show a wide variation in 

 size, and there is no law requiring a standard size, though there 

 should be one. The National brickmakers association and the 

 American institute of architects have adoj)ted a standard size of 

 2^x4:^x8^ inches. If these dimensions be compared with those 

 given in the table below, considerable difference will be observed 

 in some, cases. It is to be remembered of course, that, with a given 

 clay and a given mold, the brick will be smaller the harder it is 

 burned and in some clays the difference will be appreciable. 



Common brick should be of uniform texture, hard, and give a 

 clear ringing sound when struck. The compactness and uniformity 

 of texture are largely influenced by the method of molding. Soft 

 mud bricks when properly burned are very resistant to frost ac- - 

 tion. The absorption of common brick should not exceed 15^. 



They should also have a crushing strength of not less than 3000 

 pounds a square inch. 



The following table gives the dimensions of a number of bricks 

 made in New York state, also their absorption after 24 hours' im- 

 mersion. 



