MANUFACTURE AND PROPERTIES OF LIME-SAND BRICKS. 145 



Summary of the results of tests. The three American series of 

 tests above quoted (Tables 53, 54, and 55) were made on samples of 

 brick furnished by the manufacturers, and the results of these tests 

 are now used for advertising purposes. It seems fair to assume, there- 

 fore, that these results are not inferior to the average run, but are, 

 on the contrary, probably better than the usual American lime-sand 

 brick as found on the market. 



The bricks tested at Charlottenburg, on the other hand, were prob- 

 ably selected from marketed products, and are probably fairly repre- 

 sentative of the average German product as it reaches the building 

 trade. 



The two sets of results have therefore been averaged separately, 

 with the results given below. 



TABLE 57. 

 SUMMARY LIME-SAND BRICK TESTS. 





Comparison with clay brick. It will be of interest to compare with 

 these the results of a series of tests recently published,* which were 

 made in 1903 by Prof. Woolson in an extensive series of clay bricks. 

 The bricks were all made in New Jersey, and were fair average samples, 

 taken from stock piles. For convenience of references the bricks 

 have been divided into two classes front brick and common brick 

 and the two classes are separately averaged in the following table. 



TABLE. 58. 

 SUMMARY OF CLAY-BRICK TESTS. 



(WOOLSON.) 



Even the common clay brick, therefore, is stronger and denser than 

 the lime-sand brick. 



* Vol. 6, Reports N. J. Geological Survey. Clay Industry, p. 256. 1904. 



