a, . J Shee dda oy neata aeloe ae the stratosphere were produced by three separate events as follows: jo Latitude Region Nuclear Test 9ON ~ 40N Chinese test of September 29, 1969 40N - LON Chinese test of December 28, . French thermonuclear tests in mid~ 1968 ar LON =~ >515S 1968 The samples in Tables 3b and 3c are grouped according to the altitude of collection beginning with 19.2 km. Within each altitude group, the samples are then listed with decreasing latitude. The fractions of each individual filter making up the composite are liste immediately below the composite sample number. The collection para- meters of the composite sample and the contractor laboratory performing the analyses are given prior to the nuclide concentrations. QUALITY CONTROL To evaluate the contractor's performance in radiochemical analyses, HASL routinely submits blind duplicates, blanks and standards. The duplicates are identical composites submitted with different code numbers. The blanks are unexposed filters supplied by the Air Force. Standards are blank filters onto which calibrated solutions of various nuclides have been evaporated. II - 14