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NEW YORK STATE MUSEUM 



emery wheel 4 inelies in ^\adtli and 15 inches diameter. The 

 wheel is set vertically and given 100 revolutions a minute. The 

 cube was loaded with a weight of 10 pounds at the end of a lever 

 3 feet long, and subjected to 200 revolutions. 



The following figures given by Gary^ show the loss by abra- 

 sion which some cements suffer. 



Loss of weight by abrasion 





Length 

 of tests 



HARDNESS IN AIR 



HARDNESS UNDER WATER 



No. 



•*3 



a 

 © 



■J? '^ 

 ©" 

 a 



a 

 Si 



a 

 c a 



a 

 E c 



® C8 



t-HCO 



p 



l-H TH 



a 

 © 



CO © 



© o 



a 

 B a 



© e8 



© U3 



a 



is 



© M 



i-ei 



*» 



a 

 2-0 



c a 



© 03 

 © m 

 T-4eo 



4^ 



© w 



1... 

 2... 

 3... 

 4... 

 5... 

 6... 



j 7 days.. 



■J28 

 j 7 

 (28 



7 .. 

 (28 



(28 .. 



(28 ;; 



i 7 



(28 



5.5 

 7.9 

 4 6 

 3.9 

 5.4 

 2.4 



10.4 

 9 



10.6 

 5.3 

 6.2 

 5.3 



4.2 

 4.5 

 2.5 



1.9 



1.6 



3.9 



4 



7.6 



1.6 



2.3 



2.2 



3.5 

 1.9 

 3.4 

 3.5 

 6.1 

 1.9 

 3.9 

 3.4 

 10.2 

 1.6 

 4.2 

 3.3 



6.1 

 9.7 

 8.3 

 6 



18.3 

 2.3 

 7.3 

 5.2 



19.2 

 9 



6.5 

 4.4 



8.9 

 13.8 



9.5 



7.3 

 63.8 

 22.9 

 17.3 

 14.9 

 28.7 

 11.6 

 17.1 



8.9 



5 



2.9 



4.6 



3.6 



2.4 



2.2 



4 



3.6 



7 



5.8 



3.5 



3.9 



3.7 

 1.8 

 1.7 

 1.8 

 2.1 

 1.3 

 2.6 

 2.8 

 5.9 

 .9 

 1.3 

 1.3 



3.8 



2.7 



3 



2.3 



2.1 



1.4 



2.5 



2.1 



7.1 



1.1 



2.2 



2.2 



7.9 



4.1 

 6.5 

 5 



4.7 

 1.8 

 3.6 

 2.1 

 15.7 

 2.3 

 5 

 2.7 



10.4 



6.8 



8.8 



5.6 



15.9 



2.2 



4.6 



1.8 



17.4 



13.4 



10.9 



3.9 



No 1 a Holstein brand of cement ; 2, 3, 6 Silesian cement ; 4, 5 pozzuolana cement. 



All of these cements are said to fulfil the Prussian regula- 

 tions. They have a tensile strength after 28 days, when mixed 

 1-3, of over 230 pounds per square inch, and a compressive 

 strength of more than 2300 pounds per square inch. A sieve 

 of 900 meshes rejects less than 10;^. They are of constant volume. 



The specimens "were tested by pressing them .with a load of 

 56 pounds against a cast iron disk, rotating at the rate of about 

 22 revolutions a minute. 20 grams of l^apus quartz, no. 3, were 

 put on plate at start, and a similar quantity at the end of every 

 15th turn. 



The body is weighed when starting and again at the end of 

 the 30th revolution. 



* Trans. Am. soc. civ. eng. 80: 40. 



