A simple and rapid procedure for the determination of a small amount of lead in tin metal and tin-base babbitt metal has been studied by dithizone photometric method. Large amounts of Sn (with Sb and As) are volatilized off by dropping HBr into H
2SO
4 solution at 200230° as described in the preceding report. Using benzene in place of CCl
4 or CHCl
3 as a solvent of dithizone, only one extraction is effective by employing a solution with high pH as has been reported by Snyder. Other interfering elements in such alloys are masked by NH
2OH, Rochelle salt, and KCN as usual; and Bi as an impurity is permissible. The procedure is carried out as follows : after dissolving the sample in H
2SO
4 and volatilizing off Sn, Sb, and As, the solution is evaporated nearly to dryness, taken up in a little HNO
3. Then this solution is made up to a definite volume with water, the aliquot of the solution is treated with NH
2OH and Rochelle salt, and made strongly ammonical. KCN is added and the Pb is extracted as above.
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