There seems to be tremendous enthusiasm among young mechanicians to master thermodynamics. I have found no better source for enlightenment than Gibbs's own writings on the subject, collected in a paperback, still in print. By common consensus, his masterpiece on the subject is the 300-page paper entitled "On the Equilibrium of Heterogeneous Substances". Although I have returned to the long paper many times for illumination, my own favorites are his two shorter papers, written in 1873, before the long one. In many ways, I think, the longer paper is an elaboration of the ideas in the two shorter ones. The title of the short papers are