it is realized that the actual disintegration rate is not practically attained. The actual disintegration rate was approximated by correcting the gross ground, sample counts for back- sample weight, geometry, backscatter, coincidence and decay. self-absorption, Since it is desirable to express the amount of activity per sample in a weight unit comparable to that of living organism, wet weight was selected in preference to dried or ashed weight. Naturally the activity per unit: of wet weight is lower than per unit of dried or ashed weight. Significant Figures. Results have been recorded to two significant figures although three figures generally were used in the computations. The number of significant figures in the final answer was limited by the number of significant figures in the least accurate value in the computation. One source of limitation in the post test samples was the correction factor for decay which was changing approximately 4 percent per day and which was applied no closer than to the day the sample was counted. Another limitation occurred in the weight of the ash used to determine the correction for self-absorption. Samples were weighed to the nearest milligram and often the ashed weight was less than 100 milligrams and occasionally less than 10 milligrams. Also, the correction factors for backscatter and for geometry were not determined more accurately than to two significant figures. 3.4 Correction Factors + ebay Geometry. Geometry is about 50 percent for an internal Ri prt: