Polish on Metals

Abstract

WE are much interested in Mr. French's letter in NATURE of Jan. 30, as we ourselves have just constructed an electron camera for the examination of the polish on metals and similar problems. In an earlier paper by Prof. G. P. Thomson¹ it has been stated that no pattern was detected from polished metal surfaces, and it was felt at the time that this result was not in accord with other work then proceeding in this laboratory. It had been found² that so called amorphous substances, such as glasses of widely differing chemical compositions, gave rise to very definite X-ray diffraction patterns which bore strong similarities to the line patterns of corresponding crystalline substances. This led us to the view that, while glasses may contain some material in a truly amorphous form, the greater number of atoms are built up in the form of exceedingly small crystals, probably not exceeding 10^-6 cm. in size. At the same time, small differences were noted between the spacings of the diffuse bands of the vitreous substance and those of the corresponding completely crystalline substance.