Full Idea
For scientists 'copper' refers to something having the properties of malleability, fusibility, ductility, electric conductivity, density 8.92, atomic weight 63.54, and atomic number 19. All but the last of these are dispositional.
Gist of Idea
Scientists define copper almost entirely (bar atomic number) in terms of its dispositions
Source
Harré,R./Madden,E.H. (Causal Powers [1975], 1.II.C)
Book Reference
Harré,R/Madden,E.H.: 'Causal Powers: A Theory of Natural Necessity' [Blackwell 1975], p.12
A Reaction
This is important because it is tempting to pick the atomic number as the essence of copper, but it is the only one on the list which is structural rather than dispositional. The deep question is why that substance has those dispositions.