  The emergence of unique atomic weights and the structural formulae that organic chemistry had yielded by the 1860s were to prove vital ingredients for the case for atomism that could eventually be made. But there are reasons to be wary of the claim that atomism was responsible for the rise of organic chemistry and the extent to which the achievement improved the case for atomism needs to be elaborated with more caution that is typically the case. Glymour (1980, 226–263) offers an account of how Dalton's atomism was increasingly confirmed and relative atomic weights established by 1860 that conforms to his ‘bootstrapping’ account of confirmation, an account that is adopted and built on by Gardner (1979). These accounts do not take organic chemistry into account. In one sense, doing so could in fact help to improve Glymour's account by offering a further element to the interlocking and mutually supporting hypotheses and pieces of evidence that are involved in his case. But in another sense, the fact that organic chemistry led to unique formulae by chemical means casts doubt on Glymour's focus on the establishment of definitive atomic weights as the problem for chemistry. There is a case for claiming that correct atomic weights were the outcome of, rather than a precondition for, progress in organic chemistry prior to 1860. After all, the majority of the formulae productively involved in that dramatic progress were the wrong formulae from a modern point of view! For instance, use of homologous series to project properties of lower hydrocarbons on to higher ones are not affected if the number of carbon atoms in the correct formulae are doubled, which results from taking 6 as the relative atomic weight of carbon, as many of the contemporary organic chemists did.