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David Alter. Portrait of David Alter (1807-81), American inventor and scientist. Alter graduated from a medical college in New York in 1831, but his technical knowledge was largely self-taught. Working at home he invented an electric clock and, in 1836, an electric telegraph which spelt out words using a pointer. He also discovered a method of purifying bromine and producing oil from coal. He suggested that each element has a characterist- ic light spectrum and pioneered the use of the spectroscope in the analysis of gases & vaporised solids. This theory was later proved correct by Bunsen & Kirchoff. From 1855 Alter used spectro- scopy to determine the composition of meteors.
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