FISSION PRODUCTS IN THE ATMOSPHERE AND RAIN
603
Samples of rain and snow were collected by means of a sampling
system installed on the roof of the Chemistry Building of the University of Arkansas. This paper reviews some of the results obtained
so far.—
RADIOCHEMICAL PROCEDURES
89Sr, 90Sr, and 140Ba
Radiochemical procedures used for the determination of ®Sr,
Sr and ‘°Ba were essentially the same as those described by
Kuroda.! Further studies on the radiochemical procedures have recently been carried out by Hodges,’ and the details will be published
elsewhere.
141Ce and 144Ce
A radiochemical procedure
which has recently been developed at
the University of Arkansas? was used for the determination of radiocerium. The method depends on the oxidation—reduction and liquid—
liquid extraction cycle with the use of a tri-n-butyl phosphate (TBP)-—
carbon tetrachloride mixture
(20% TBP by volume) as the organic
solvent.
124Sb and 125Sb
Radiochemical procedures that were used for '4Sb and '**Sb have
been recently described by Kauranen.*
54Mn
After the antimony fraction was removed, sulfides of iron, manganese,
ruthenium,
cobalt, etc., were precipitated by the addition of
NH; and (NH,).S. The precipitate was leached with 1% HCL. The HCL so-
lution was then boiled to expel H,S. Ammonium hydroxide was addedto
precipitate iron etc., and manganese was precipitated againas the sulfide. The precipitate was leached with 0.5N HNO, the solution was made
2N in HNO;, and saturated NaBrO;solution was added. The precipitate
of MnO, was filtered on a glass-fiber filter paper, washed with water
and acetone, dried, weighed, and counted with a 3- by 3-in. Nal(T1)
crystal and a multichannel analyzer.
The chemical yield was determined after counting. The precipitate
of MnO, was dissolved in H,O,, diluted, and filtered, and 6N HNO, was
addedto the filtrate. A slight excess amountof solid NaBiO; was added,
and the solution was filtered through a fritted glass filter. A known
excess of standard FeSO, solution was added, in excess, to the filtrate.