19 @ Shape--both spheroids and irregular, larger particles with small spheroids attached. ® Distribution of radioactivity--some particles radioactive throughout, some particles radioactive only on or near the surface. These properties indicate that after the liquid particles solidify, they begin to agglomerate with the irregularly shaped dust particles and with each other. The daughters of the nuclides in the gas phase are continually being deposited on the surface of al] particles until the particles fall out of the gas cloud. The refractory elements in a given fallout sample are acquired partially by agglomeration, but the volatile elements all are acquired by condensation on a solid surface. The spheroidal particles in a sample should show a strong inverse relation between r(A) and particle size. On the other hand, the irregular particles in a sample, having been sieved, contain variable (indeterminate) relative amounts of solid particles and gaseous condensate. Therefore, in a sample containing both spheroidal and sieved irregular particles, the relation of r(A) to particle size will depend on the relative amounts of spheroidal and irreqular particles in the sample. The inverse relation of r(A) and particle size is easily seen in the Smoky data. There is less of a trend in the Shasta data and still Jess in the Diablo data.