Bertram Borden Boltwood (July 27, 1870Amherst, Massachusetts - 1927, Hancock Point, Maine) was an American pioneer of radiochemistry. July 27 is the 208th day (209th in leap years) of the year in the Gregorian Calendar, with 157 days remaining. ... 1870 (MDCCCLXX) was a common year starting on Saturday (link will display the full calendar) of the Gregorian calendar (or a common year starting on Monday of the 12-day slower Julian calendar). ... Amherst is a town in Hampshire County, Massachusetts, United States. ... 1927 (MCMXXVII) was a common year starting on Saturday (link will display full calendar). ... Radiochemistry deals with the use of radioactivity to study ordinary chemical reactions. ...
He was a graduate of Yale University, and taught there 1897-1900. He measured the age of rocks by the decay of uranium to lead, in 1907. He got results of ages of 400 to 2200 million years, the first success of radiometric dating. More recently, older mineral deposits have been dated to about 4.4 billion years old, close to the best estimate of the age of earth. “Yale†redirects here. ... Radiometric dating is a technique used to date materials based on a knowledge of the decay rates of naturally occurring isotopes, and the current abundances. ... Radiometric dating is a technique used to date materials based on a knowledge of the decay rates of naturally occurring isotopes, and the current abundances. ... The oldest known object on Earth is a tiny speck of zircon crystal. ... The age of the Earth is estimated to be 4. ...
Boltwoodite is named after him.
Reference
Boltwoood, Bertram (1907) "The Ultimate Disintegration Products of the Radio-active Elements. Part II. The disintegration products of uranium." in American Journal of Science series 4, volume 23, pages 77-88.
External links
Science Odyssey: Radiometric dating finds Earth is 2.2 billion years old
Boltwood studied this concept of "radioactive series," and found that lead was always present in uranium and thorium ores.
Boltwood's basic idea and technique have been used ever since 1907, but advances in technology and knowledge of atomic structure have shown the earth to be even older.
Boltwood's reasoning holds true for other radioactive elements such as carbon-14, which has been used to date artifacts within human history.
Boltwood had conducted studies of radioactive materials as a consultant, and when Rutherford lectured at Yale in 1904, Boltwood was inspired to describe the relationships between elements in various decay series.
Boltwood did the legwork, and by the end of 1905 had provided dates for 26 separate rock samples, ranging from 92 to 570 million years.
Boltwood's paper pointed out that samples taken from comparable layers of strata had similar lead-to-uranium ratios, and that samples from older layers had a higher proportion of lead, except where there was evidence that lead had leached out of the sample.
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