THE ATOMIC VISION: DALTON AND ARITHMETIC OF MATTER

A Quaker schoolmaster who could not tell a scarlet geranium from its leaves, and who believed until his dying day that the fluid in his own eyeball was tinted blue, gave chemistry the one thing it had been missing for two thousand years. It was not the atom. Atoms were free. Democritus had them, Newton had them, and a quarrelsome Irishman named Higgins very nearly had them in print before Dalton did. What nobody had was a number. John Dalton weighed the invisible. He decided that matter came in whole steps, that those steps could be counted, and that the counting could be written down in a table. Almost every value in that table was wrong. Water was not HO. Ammonia was not NH. His atomic weights were off, his rule for choosing formulas was an admitted convenience that everyone forgot was a convenience, and the founder of the atomic theory spent the last thirty years of his life as its single most effective obstacle, refusing the very evidence that would have repaired it. None of it mattered. The integers survived, and the magnitudes were replaced one by one, which is the true shape of most scientific progress and almost never the shape in which it is told. >Keywords: John Dalton, atomic theory, history of chemistry, atomic weights, color blindness, philosophy of science, scientific discovery