: | . ! about 10 days, they were assumed to be in equilibrium with our diet and to eliminate (as the average of our control group) 2 grams of K per day in the urine and 0.5 gram per day in the feces. Knowing the K contents of the samples collected, this assumption permits a not-too-far-fetched extrapo- lation to the daily excretion rate. The Zn® data are given in Table 10. An average of 6.7 tic of zn per mic of Zn® present in the total body is eliminated with each gram of K in the feces. The Zn™ amount present in the urine is negligible. On the basis of 0.5 gram of K eliminated per day by the fecal route, 3.4 uc zn per muc Zn® in the body would be eliminated per day. The biological half-time for the element is thus 200 days. An effective biological half- time of 110 days results by adding the effect of the physical half-life of 245 days. This is considerably longer than the published values. TABLE 10 Subject j 4 Feces ze Oe no data Urine zn Smee - 3340 6 536 82 q 8 236 1340 - 42 7 183 - 5 10 280 Body burden - - 29.5 482 73 Hic Zn& per gram in feces mute Zn®*in body 7 . 7.4 62.1 3.8 29.5 6.3 229 29.5 K 59 9.7 average 6.7 bs i 4s PER, Gt . The Cs'3" data on two subjects are given in Table 11; they similarly are based on the American average of 2 grams of K eliminated in the urine per day and 0.5 gram of K in the feces per day. The effective biological half-time was 92.4 days for Subject 5 and 157 days for Subject 8. The average of these values is in essential agreement with values found under controlled conditions. SO1Z13b