clay* working industries, 

 comparative standing. 



19t» 



Based on the Average Rank obtained on the Absorption and Rattling Tests— and 

 excluding the Crushing Tests. 



Paving Brick Tests. 



The results of this test, which is by all means the largest and most 

 complete investigation of its kind yet made, are of great interest in many 

 ways. Not only is it interesting to brickmakers, who are competing for 

 standing, but it is interesting to the public at large, to see that material of 

 such excellence, and such high average excellence can be produced by our 

 Ohio manufacturers. 



By a careful study of these tabulated results, the following deduc- 

 tions have been made: 



1. Fire clays vs. Shales. Twenty-three varieties of shale brick, or 

 bricks whose largest constituent is shale, and whose color is red or dark 

 were grouped together. 



Fifteen varieties of fire-clay brick, or bricks whose largest constituent 

 is fire-clay, and whose color is light (gray bluish, or buff), were grouped 

 together. 



Four varieties, composed of a shale fire-clay mixture in about equal 

 proportions, and whose color is speckled white and red, were grouped 



together. 



Three varieties, composed of Ohio river sedimentary clays exclusively, 

 and whose color is dark red brown were grouped together. 



