8 which interacted with the radioactive cloud at a different time, Earlier interaction generally corresponds to lVaraer particles, more high temperature effects un the particles, and greater enrichment in refractory radioisotopic sphere. Later interaction corresponds to smaller particles, less temperature effect on the vartictes, and qreater enr*ch- ment in surface distributed volatile species. Later fractionation of radionuclides between the different phases of an interacting environment were reported in the same year by Freiling and Ballou (1962). Freiling had previously characterized this "secondary" fractionation in terms of the “degree” and “extent" to which it occurred. The term "degree of fractionation" was coined to refer to the range of variability of radionuclide ratios present in different collections; whereas, the term “extent of fractionation was coined to refer to the quantity of a radionuclide which was not Present in a sample or phase in its ratio characterized by its production. There were 23 detonations reported at Bikini at ten locations, as snown in Fig, 2. The parameters for these detonations are given in Table }. yields of the largest reported detonations were: The Bravo, 15 MT in 1954 at location B; Zuni, 3.53 MT in 1956 at location H; and Tewa. 5.07 MT in 1956 at location G. There was also a “several MT" airburst detonation in 1956 re- ported which probably resulted in relatively minor contamination of lagoon sediments. Typically, two types of sites were used for testing nuclear devices at Bikini--barge and surface--and each probably gave rise to fallout particles of distinctly different composition and structure. The first type was located on barges anchored over water deep enough to Prevent the incorporation of large quantities of soil in the ensuing fireball] and cloud (sites A,F,D,E in Fig 2). Devices detonated on barges at Bikini under these conditions contained large and similar quantities of fron and calcium (from coral barge ballast) as the principal condensation matrix (Adars et al. ,op.cit.). Spherical particles of dicalcium ferrite (2Ca0 Fe203),