G. W. C. Kaye. The Practical Applications of X-Rays. London, Chapman & Hall, 1922. Pp. VIII + 135.

Kaye. Practical applications of X-rays.

Advances in X-ray technology have brought to life a new field of application for X-rays—industrial applications. Very hard rays, obtained with the aid of modern apparatus, make it possible to photograph pieces of metal and entire metal parts of machines—and to reveal in them defects, voids, cracks, etc., inaccessible to detection by other means. Very soft rays make it possible to obtain unusually delicate photographs of wooden parts, for example of airplane wings; in these photographs all defects, inhomogeneities, poor gluing, etc., are revealed with perfect clarity. With the aid of X-rays, metallic alloys are investigated, the microcrystalline structure of metals and the influence upon it of various treatments are studied, and X-ray spectral analysis is developing (qualitative, and even quantitative). The extraordinary simplicity of the X-ray spectra of the elements, and their complete independence from chemical compounds, promise a great future for this latter method1. Finally, in the very latest years, a completely unexpected field of application of X-rays has begun to develop: the examination of paintings by old masters, which has made it possible, for example, to distinguish genuine paintings by great artists from later forgeries.

Both books, whose titles are given above, are devoted to these curious new applications of X-rays. Both are written in a popular manner and intended for a wide circle of readers. In particular, Kaye’s book is written with the skill usual for this author and is supplied with a large number of interestingly chosen and excellently executed illustrations.

E. Shpolsky.

1. Here it is appropriate to recall, incidentally, the discovery of hafnium and the determination of its content in zirconium minerals, carried out precisely by this method (see the article by F. Paneth, “On Element 72,” Uspekhi fizicheskikh nauk, vol. I, issue 1). ↩