off the fine fractions on each of those grindings. We do the sieving because the fine fraction tends to cushion the oversize material that we are trying to abrade. We had an interesting occurrence in that every time we pried up the lid of the can there was a puff of what looked like smoke. kinds of extremes awhile. to avoid that. We cleaned We went to all up rather frequently for We finally avoided that and a related problem ended by simply puncturing the bottom of the can, that vents the air that's been heated up by the ball-milling process, and we continue by cutting out the entire bot10 tom of the can (REECo 81). 11 the can and it also makes the transfer of the material out of the can a lot 12 easier because you are pouring it across a smooth surface instead of across 13 a rim. That does away with stone lodging in the rim of 14 The steel balls are retrieved after the grinding session (REECo 82), 15 and we now come to the part which jis an absolute art, and that is, turning 16 the can upside down, 17 spilling it or dropping the whole thing. 18 Eddie Eubank have developed this talent to a high degree. onto the sieve (REECo 83), without making dust or Richard Grisham in the back and 19 For those of you who have not seen a soil sieve (REECo 84), the set 20 consists of a metal pan. in which the "less-than" fraction is collected, the 21 brass screen, which does the separating, and the metal cover which keeps us 22 from contaminating the rest of the laboratory. 23 together as shown in the previous slide, and the separating is done on the 24 vibratory shaker (REECo 85). 25 separation is a function of the characteristics of the soil that is on the 26 screen. 27 20 or you'll sieve for six. hours at a setting of 75. 28 much more successful if you listen to the vibrator and the screen will tell The three parts are taped This, also, is an art. The time to reach You cannot say that you will sieve for ten minutes at a setting of 144 It has been found