PHILIPPINE SOILS. 



319 



Substituting for the constant — j— its value in { 3 ) and ( 2 ) we obtain 

 h„=0.245 v„2+l-59 (centimeters). 

 v„=],/hn — 1.59x2.02 (centimeters per minute). 

 In order to be able to determine the velocity of the water at any given 

 instant in the elutriating tubes and therefore the corresponding diameter of 

 the soil particles in suspension a large niunber of values are computed in ac- 

 cordance with the above formula and tabulated as follows : 



Table XII. — The height of the water in the piezometer required to remove soil 

 particles of given diameters. 



Height in 



piezometer 



in centi- 



Velocity in millime- 

 ters per sec. in the elu- 

 triating tubes. 



Corresponding diame- 

 ter of soil particles 

 in millimeters. 



meters. 

 h. 



V. 



d. 



TubeB.> 



Tube A. 



Tube B. 



Tube A. 



1.8 



b 0. 154 



0.636 



0. 0095 



0. 0235 



1.83 



0. 166 



0.685 



0. 0100 



0. 0247 



2.0 



, « 0.216 



0.892 



0. 0118 



0. 0296 



2.5 



0.321 



1.326 



0. 0152 



0. 0376 



3.0 



0.400 



1.651 



0. 0175 



0. 0432 



3.5 



0.465 



1.921 



0. 0193 



0. 0476 



4.0 



0.523 



2.159 



0. 0208 



0.0512 



4.5 



0.574 



2.370 



0. 0221 



0. 0544 



5.0 



0. 622 



2. 568 



0. 0232 



0. 0572 



6 



0.707 



2.919 



0. 0252 



0. 0620 



7 



0.783 



3.232 



0. 0269 



0. 0662 



8 



0.853 



3.519 



0. 0284 



0. 0699 



9 



0.917 



3.784 



0. 0297 



0. 0732 



10 



0.977 



4.031 



0. 0309 



0. 0762 



15 



1. 233 



5.090 



0. 0359 



0.0884 



20 



1.445 



5.965 



0. 0397 



0. 0978 



21.24 



1.496 



6.175 



0. 0406 



0. 1000 



25 



1.629 



6.709 



0. 0428 



0. 1054 



30 



1.782 



7.356 



0. 0454 



0.1118 



35 



1.947 



8.037 



0. 0480 



0. 1183 



39.6 



2.077 



8.574 



0. 0500 



0. 1232 



40 



2.087 



8.615 



0. 0.502 



0. 1236 



45 



2.218 



9.156 



0. 0521 



0. 1285 



50 



2.343 



9. 672 



0. 0540 



0. 1331 



60 



2.573 



10. 623 



0. 0573 



0. 1413 



70 



2.785 



11. 497 



0. 0603 



0. 1485 



80 



■1 2. 982 



12. 310 



0. 0644 



0. 1551 



90 



■^3.165 



13. 065 



0. 0654 



0. 1611 



100 



3.340 



13. 788 



0. 0677 



0.1668 



" The velocity in this straight-sided tube is 4.128 times that in the large tube for this 

 number expresses the relation of the square of the respective radii. 

 » Observed 0.153. 

 = Observed 0.216. 

 1 Observed 2.982. 

 « Observed 3.160. 



A 20-gram sample of air-dried soil is taken for each analysis. That portion 

 which remains in suspension after disintegration (cf. p. 320 et neq.) is carefully 

 decanted into the Schone tube of the apparatus and the coarser portion rinsed 

 into the straight-sided tube. The apparatus is closed, the stopcock opened so that 

 the water is allowed slowly to enter, care being taken to avoid attaining more than 

 the lowest required velocity imtil the air is expelled and the oiitfiow begins. 



