  Phenomenological thermodynamics, based on the law of conservation of energy and the law ruling out spontaneous decreases in entropy, supported an experimental programme that could be pursued independently of any assumptions about a micro-structure of matter underlying properties that were experimentally measurable. The programme was developed with impressive success in the second half of the nineteenth century. Especially relevant for the comparison with atomism is the extension of thermodynamics, from the late 1870s, to include chemistry.  Two of the striking accomplishments of the programme were in areas that had proved a stumbling block for atomism, namely, thermal dissociation and chemical affinity.