69 



and .should be removed by further decantatiou. The sediment in tlie l)ottoin of 

 beaker "A" should also be tested. If it contains particles larger than 0.05 milli- 

 meter, the washing or deeantation was too rapid. In this case a recovery must be 

 made. 



The sand is transferred from the beaker to a porcelain dish and ilried. It is then 

 ignited to destroy organic matter, after which it is sifted through a nest of sieves of 

 1, 0.5, 0.25 and O.I millimeter, respectively, that going through the finer sieve being 

 known as very fine sand. These live sejiarations 

 are weighed together I>efore the sifting and .sepa- 

 rately after sifting. 



The amount of silt, fine silt, and clay which was 

 washed away from the sand may be obtained approx- 

 imately by subtracting the total weight of sand, 

 moisture, and organic matter from the eartli taken 

 (20 grams). 



Considerable time an(_l skill is required to make 

 the separation of silt,, fine silt, and clay. It will not 

 be attempted in tliis experiment. 



Fig. 20. — Card's apparatus for testing the adhesiveness of soils. 



The following are the sizes into wliich the soil ]iarticles are separated: 



No. 1. Gravel, 2-1 millimeters. 



No. 2. Coarse sand, 1-0.5 millimeter. 



No. 3. Medium sand, 0..5-0.25 millimeter. 



No. 4. Fine sand, 0.2.5-0.1 millimeter. 



No. 5. Very fine sand, 0.1-0.05 millimeter. 



No. 6. Silt, 0.05-0.01 millimeter. 



No. 7. Fine silt, 0.01-0.005 millimeter. 



No. 8. Clay, 0.00.5-0.0001 millimeter. 



Students are required to keep a careful record of each experiment, and at the end 

 of the term to present plates showing their results, and also illustrations of apparatus 

 used, together with description of the method employed. 



Exhibit No. 8. 



DETAILED SCHEDULE OF LABORATORY WORK. 



Adranced courier, in soih. 



September IS and 19. — Collected samples of soil from fallow, alfalfa, and corn 

 ground to determine moisture content of first and second foot, using sampling tubes 

 and other apparatus, as illustrated in fig. 21. 



