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zz <br />I • solution of NaP03 and shaking the suspension for six hours. The sodium <br /> solution dispersed any clay aggregates which might have otherwise <br /> behaved as coarser material. The dispersed suspension was put in a one <br /> liter graduated cylinder and filled to 1000 ml with water. The 1000 ml <br /> suspension was mixed by inverting it several times, then a hydrometer <br />~ reading was taken 40 seconds after mixing. Presumably all sand, and <br /> only sand, settled during the 40 seconds of quiescence. Two hours after <br /> mixing, another hydrometer reading was taken. Prior to the two hour <br /> reading most suspended silt was given an opportunity to settle with most <br /> of the clay left in suspension. The hydrometer was calibrated to the <br /> water temperature and NaP03 solution. Percent clay by weight was equal <br /> to the calibrated hydrometer reading at 2 hours, percent sand by weight was <br /> equal to 100 minus the calibrated reading at 40 seconds, and percent silt <br />• by weight was equal to the difference between the two calibrated hydrometer <br />~ readings (Day, 1965). <br /> After the hydrometer test, the entire contents of the graduated <br /> cylinders were washed through No. 120 and No. 230 sieves to determine the <br /> amount of very fine sand (between 125 microns and 63 microns). The very <br /> fine sand was oven dried and weighed. The amount of very fine sand <br /> was subtracted from the amount of sand determined by the hydrometer test <br /> so sand plus silt plus clay plus very-fine-sand totaled 100 percent for <br />each sample. <br />Organic Matter <br />Several field samples were burned in an oven at 750°C for four hours. <br />The difference in weight of the samples after burning compared to the <br />• <br />