38 



PRATT. 



fairly be taken to represent the limit of accuracy attainable by the centri- 

 fugal method under the most favorable conditions" as follows: 



Soil. 



Diameter 

 of grains. 



Sample No. 5862— 



(a). (6). (c). (d). (e). (/). {g). (A) 



Loss on ignition _ 



Fine gravel 



Coarse sand 



Medium sand 



Fine sand 



Very fine sand 



Silt 



Clay 



2. -1. 

 1.0 -0.5 

 0. 5 -0. 25 

 0. 25-0. 10 

 0.10-0.05 

 0. 05-0. 005 

 0.005 and 

 less. 



Perct. 



12.5 

 2.6 

 5.3 

 4.2 



13.0 

 7.7 



16,8 



38.3 



Perct, 



12.2 



2.6 



5.1 



4.8 

 13.2 



7.3 

 17.6 

 37.5 



Perct. 



10.9 

 2.6 

 5.1 

 4.6 



14.2 

 8.8 



15.8 



38.1 



Per ct. 



12.2 

 2.4 

 5.1 

 4.5 



13.8 

 7.2 



16.7 



37.9 



Perct. 



12.0 



■ 2.4 



5.3 



4.4 



14.4 



7.8 



16.0 



38.0 



Per ct. 



12.2 

 2.3 

 5.6 

 4.5 



12.8 

 8.0 



16.4 



38.0 



Per ct. 



12.4 

 2.8 

 5.6 

 4.9 



13.6 

 8.4 



15.1 



37.6 



Per ct. 



11.9 

 3.2 

 5.2 

 4.4 



12.6 

 7.3 



17.2 



37.7 



The following table shows duplicate analyses of 5-gram samples of 

 the same soil run in the same set in the chemical laboratory of this 

 Bureau. 



Soil. 



Diameter 

 of grains. 



71 A. 



71 A. 



Sampl 

 73 A. 



e No.— 

 73 A. 



87. 



87. 



Fine gravel 



Coarse sand_ 



mm. 

 2.0-1.0 

 1.0 -0.5 

 0. 5 -0. 25 

 0. 25-0. 10 

 0.10-0.05 

 0. 05-0. 005 

 0. 005 and 



less. 



Per ct. 



0.2 



0.2 



2.5 



15.5 



23.7 



43.4 



Per ct. 



0.2 



0.2 



0.6 



16.1 



23.0 



43.4 



Per ct. 



9.7 



1.7 



9.2 



10.6 



11.2 



35.6 



Perct. 



9.7 



1.6 



9.0 



11.7 



11.8 



35.5 



Per ct. 

 2.6 

 1.1 

 3.5 

 8.4 

 12.7 

 34.7 



Perct. 

 2.6 

 1.3 

 3.6 

 7.4 

 12.8 

 34.5 



Medium sand _ - 



Fine sand 



Very fine sand 



Silt 



Clay 



Total __ 















99.8 



100.3 



100.6 



100.6 



100.1 



100.4 







The following table shows duplicate analyses -at 5-gram samples of 

 several soils, run in different sets: 



Soil. 



Diameter 

 of grains. 



Sample No.— 



1 



6. 



6. 



6. 



7. 



7. 



7. 



8. 



8. 



Fine gravel 



Coarse sand 



Medium sand 



Fine sand _ 



mm. 

 2. -1. 

 1.0 -0.5 

 0. 5 -0. 25 

 0. 25-0. 10 

 0. 10-0. 05 

 0. 05-0. 005 

 0. 005 and 



less. 



Per ct. 

 4.3 

 3.4 

 10.6 

 11.5 

 14.3 

 37.6 

 18.4 



Per ct. 



4.3 



3.4 



■ 11.2 



11.7 



14.5 



35.7 



18.9 



Per ct. 

 4.3 

 3.0 

 11.3 

 12.1 

 13.8 

 35.7 

 19.8 



Per ct. 

 8.2- 

 1.7 

 10.4 

 12.8 

 12.7 

 33.5 

 20.5 



Per ct. 

 8.2 

 2.0 

 11.1 

 13.8 

 12.1 

 31.8 

 22.1 



Per ct. 

 8.2 

 2.0 

 10.5 

 12.7 

 12.0 

 31.4 

 21.9 



Per ct. 



1.9 



3.3 



6.1 



9.3 



12.7 



41.4 



26.7 



Perct. 



1.9 



1.3 



5.7 



9.0 



13.0 



45.9 



25.1 



Very fine sand 



sut 



Clay 



Total 



99.7 



100.0 



100.1 



100.0 



100.0 



99.8 



99.7 



99.9 







