Abstract
For ten years after the brilliant deduction of the phase rule in 1874 by Willard Gibbs at Yale the work lay buried in the archives of the Connecticut Academy of Science, undisturbed and uninterpreted. It was not until 1884 that Roozeboom of Belgium, who was working on methods of separating salts found in the Stassfurt mines, penetrated the mathematical mist surrounding the subject and saw a practical application of the work, so highly theoretical. Roozeboom was the one who introduced the phase rule as a practical tool for studying heterogeneous equilibria, and as a result of his work much research has been done on the many possible systems. Investigators have done well in elucidating the behavior of solids, liquids, and gases in various combinations --- all in fact, excepting systems of liquids in liquids. Not only is the amount of information concerning these systems comparatively limited; the methods for studying them are few.