Page:Popular Science Monthly Volume 66.djvu/198

194 I do not need to state that industrial applications will not be the object of the work. I have left my native land because I know that in Germany, more than elsewhere, we find widespread the conviction that the pursuit of knowledge for its own sake is the highest aim of human efforts."

The special form of the problem was a systematic study of the conditions of equilibrium in their bearing on the salt deposits at Stassfurt, but the general results are applicable to all cases in which the deposits consist chiefly of any mixtures of the chlorides and sulphates of sodium, potassium, magnesium and calcium. Although not yet finished, the work is a masterpiece and shows what can be expected from an application of physical chemistry to geology and mineralogy.

The work of van't Hoff can be divided crudely into four parts: 1872-1877, organic chemistry; 1878-1884, chemical affinity; 1885-1895, theory of solutions; 1896-1904, oceanic deposits. Much of the organic chemistry of today is the direct outcome of the work done in the first period; the second and third periods made physical chemistry