Yellow Rock Salt from Hall in Tirol

Abstract

SINCE the fundamental researches of II. Siedentopf on the constitution of blue rock salt, the work done in this Institute and in the laboratories in Gottingen (R. W. Pohl), Halle (A. Smekal) and Berlin (O. Hahn) has gone far to prove that the natural blue rock salt owes its colour to some radiation, most likely of radioactive origin. An argument sometimes brought forward against this view was based on the fact that the primary colouring of rock salt by radiation is yellow, a colour not found in natural rock salt, such yellow salt as exists being coloured not by radiation, but by the presence of iron or hydrocarbons