Abstract
In a previous communication an account was given of comparative measurements of the wave-length of the line λ = 4058 Å. in the spectra of ordinary lead and of the leads obtained from uranium and thorium minerals respectively. The line λ = 4058 Å. is the strongest line in the arc spectrum of lead and the results obtained were λ (lead from pitchblende) — λ (ordinary lead = 0·0050 ± 0·0007 Å. λ (ordinary lead) — λ (lead from thorite) = 0·0022 ± 0·0008 Å. The lead from pitchblende had been extracted from some Joachimstal pitchblende residues, and since this mineral is known to be free from thorium there was no reason to suspect that the sample of lead obtained was contaminated with lead of a thorium parentage. It was not known whether any ordinary lead was present but the wave-length difference which was found agreed closely with the value found by Aronberg in a comparison of the same spectrum line of ordinary lead and a sample of lead from Australian Carnotite for which Prof. Richards had found an atomic weight of 206·318.
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Schedule a callMore From: Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character
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