92 KANSAS ACADEMY OF SCIENCE. 



high, this is evidence that loss by abrasion chiefly has occurred. The 

 flatter the curve, as a whole, the better will the brick wear in the 

 street. Tests of brick giving high curves are invariably very dusty 

 after 400 revolutions. A smooth curve indicates a brick of quite uni- 

 form structure and texture ; an irregular one, like some shown in fig- 

 ure 8, for example, indicates some structural defect. In the case cited, 

 the trouble was largely due to a curve and some separation of the 

 concentric layers. 



The method which puts brick only in the rattler has been aban- 

 doned for the shot method — partly because it was too severe, giving 

 high percentage losses, and partly because it gave too much im- 

 portance relatively to the impact side of the test. The present prac- 

 tice puts into the rattler twelve brick with 225 pounds of cast-iron 

 cubes, one and one-half inches on each edge, and seventy-five pounds 

 of larger cast-iron blocks, two and one-half by two and one-half by 

 four and one-half inches. The results of tests by the shot method 

 are shown in table IV and figure 6, and these will be self-explanatory. 



In figure 7 are shown the results of tests made to determine the 

 effect of water on the brick on the rattler losses. The Topeka ^nd 

 Galesburg brick absorbed but small quantities of water. For the 

 Pittsburg, the wet weight of the soaked lot was about one pound in 

 excess of dry weight. The Coffeyville, a gas-burned brick, and 

 therefore more porous, had absorbed about a total of two pounds. 

 During testing, dust began flying at 200 to 400 revolutions for the 

 first two named, at 800 for Pittsburg, and 1100 for Coffeyville. The 

 significant thing here is, that all brick should be rattled dry, if the 

 results are to be compared. 



In figure 8, the curves for Buffalo brick show in a marked way the 

 effects of everburning — a loss of toughness and increased brittleness. 

 The curves for Lawrence were chosen because they illustrate irregu- 

 larities due to imperfect structure, and at the same time the effects of 

 underburning — softness and little resistance to abrasion. These lines 

 are not to be taken as characteristic of Lawrence brick, w^hich now 

 rank well and among the best made in the state. 



In all of the tables, like laboratory numbers refer to the same lot 

 of brick and received at the laboratory at the same time. 



