PRACTICE IX 



TESTING THE TENACITY OF MOIST SOILS 



Two students may work together. 



Use the gray silt or gray silt loam, brown silt loam, and the 

 clay or clay loam. 



Weigh out three 200-g. samples of each soil in a pan, and mix 

 by hand enough water with the first to bring it to a maximum 

 adhesiveness, as near as you can judge. 



Carefully measure and record the amount of water used. To 

 the second sample add 10 cc. more water, and to the thkd 20 cc. 

 more than to the first sample. 



Fasten the cages together firmly, pack the moist soil into 

 them, and scrape off level with top of cage. Attach the weight 

 bag, release the movable cage, and pour fine shot into the bag 

 slowly until the soil column breaks. Weigh the bag and shot. 

 Put the movable cage in place, but not having ends of the soil 

 columns in contact with each other, and determine the weight 

 necessary to overcome friction. Subtract this from the previous 

 weight. The result represents the tenacity of a column of moist 

 soil 1 square inch in cross section. Make a duplicate test. 



Sample No. 1 made up to maximum tenacity should be used 

 immediately in Practice X. 



How does fineness of grain affect tenacity ? 



What effect has undecomposed organic matter on tenacity ? 



What term is applied to very tenacious soils ? 



What are the differences in the working of these soils ? 



References. 



" Soils,'' Lvon and Fippin, pp. 97-99 and 129. 



" Physical Properties of Soil," Waringtou, pp. 23-25. 



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