An Address to Those Chemists Who Wish to Examine the Laws of Chemical Proportions, and the Theory of Chemistry in General

Abstract

As we saw in the second of the excerpts from Dalton, one way in which to evaluate his law of multiple proportions was to confront it with examples of different kinds of compounds that had been reliably generated by chemists, to see whether or not those compounds continued to have straightforward, Daltonian explanations. Could we make sense, for instance, of an oxide of iron containing 37.8 parts of oxygen to every 100 parts of iron? Dalton said that we could, if it were a compound composed of two atoms of red iron oxide (100 iron : 42 oxygen) and one atom of black iron oxide https://www.w3.org/1998/Math/MathML" display="inline"> ( 100 iron : 28 Oxygen ) − since ( 42 + 42 + 28 ) ÷ 3 = 37 ⅓ https://www.w3.org/1999/xlink" xlink:href="https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781003263845/2c38c947-379a-4a74-92a9-e8a166844908/content/ieqn0017.tif"/> . The Swedish chemist Jöns Jacob Berzelius (1779–1848) was an important player in these early debates surrounding the atomic theory. He invented “the first chemical notation that is recognizably similar to our own, in which letters are used as chemical symbols and the numbers of atoms of each species in a compound are clearly indicated,” some examples of which we see in this excerpt. 1 His broader chemical theory, of which we see only an inkling here, combined Dalton’s atomism with a theory of the electrochemical properties of the elements – giving him the ability to build a unified approach on which “composition, reactions, properties, classification, and affinities could all be explained by the same theory.” 2

Topics & Concepts