Polymorphism, Principally of the Elements, up to 50,000 kg/cm2

A new technique is described by which pressures of 50,000 kg/${\mathrm{cm}}^{2}$ and more may be applied to solids, and the parameters of any transitions measured. A systematic examination has been made for polymorphism of many of the elements in the new pressure range. New modifications are found for Bi, Hg, Tl, Te, Ga, and ${\mathrm{I}}_{2}$, and the transition parameters measured. A beginning has been made of a systematic study of polymorphism of compounds, and results obtained for KCl, KBr, and KI, which assume at about 20,000 kg/${\mathrm{cm}}^{2}$ presumably the CsCl type of structure.