| Date | Text | |
|---|---|---|
15 Aug 1927
nbsp;Bertram B. Boltwood |
death nbsp;Bertram B. Boltwood Died 15 Aug 1927 at age 57 (born 27 Jul 1870). Bertram Borden Boltwood was an American chemist and physicist whose studied the radioactivity of uranium and thorium, and their resulting products, which laid a foundation for the concept of isotopes. Boltwood traced each “radioactive series” of radioactive elements in rocks as they sequentially disintegrated into other isotopes or elements. He noted (1905) that the lead, a stable element, always found in such ores, was apparently the ending product of radioactive decay. Since each step in the decay occurs with a known half-life rate, he proposed (1907) that the ratios of the original radioactive elements to their various decay products could be used for dating rocks. Thus, with these measurements of the composition of such ores in the earth's crust, the age of the planet could determined. He estimated 2.2 billion years. Overwork, stress and depression led to suicide. |
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