Cohesion of Solids Under Great Pressure
SOME interesting experiments have been made by M. W. Spring, who has subjected a number of finely-divided substances to a pressure calculated to be equivalent to 20,000 atmospheres. Potassium nitrate and sodium nitrate were generally converted into a perfectly homogeneous mass, which was harder and denser than the fused salt, and was translucent like porcelain. Sawdust exhibited a “slatey” cleavage, and had a density more than three times that of the wood from which it was made. The author points to these experiments as having established the possibility of causing cohesion of solid bodies by the application of great pressure, unmindful of the fact that what are called dust-tiles are largely manufactured by this very method. How far the effects of simple pressure are taken into consideration by geologists in their study of the solid layers of the earth’s crust is open to question.—Academy.