“The X-rays give us one of the easiest ways to detect the alteration of checks and other documents. It is seldom that such an alteration is made with exactly the same ink used on the original. Inks even of the same color, differ in the way they affect the rays. In most cases all that is necessary to detect an alteration is to place the suspected document for a moment under the X-rays and make a photograph of it. The new ink used in the alteration will stand out clearly as different from the old. “The industrial detective will find X-rays just as useful. The adulteration of foods by sawdust, sand or clay; the adding of too much filler to paper; the presence of grit in lubricating oil, all will be revealed. “Another use of the rays comes home to every cook and housewife. X-rays constitute the only sure way to tell good eggs from bad. Pass each egg in turn through the X-rays and let its shadow fall on a chemical screen. You will see exactly what is inside each egg. The ones containing hopeful chicks may be rejected.” One of the most remarkable economic or biological uses of the X-ray so far developed is the study of silk-worms and their diseases. The Silk Association of America has established a laboratory—Department of Sericulture—in the Canton Christian College, presided over by a staff of Chinese and foreign entomologists. Here the silk-worm is X-rayed by powerful microscopes, and all his disorders diagnosed and corrected, says Mr. Philip A. Yountz (_Scientific American_, September, 1925). “Numerous autopsies on deceased members of the silk-worm tribe revealed that from 50 to 100 percent of the worms raised in South China were infected with diseases that made the infant mortality rate excessively high and destroyed the value of the silk from those hardy enough to survive. The elimination of these diseases would enable South China to produce four or five times as much silk.” In Great Britain, X-rays are used in the analysis of coal, the method being an adaptation of the X-ray stereoscope. In Berlin, S. Nalken, a noted criminologist, has devised an important improvement in finger-print identification. X-ray pictures are obtained of the finger, with the muscles and bones. This is done without the use of any chemicals that could obstruct the delicate furrows of the finger lines. Moreover, the finger bone is shaped so characteristically as to aid identification. Whenever a certain likeness of finger-lines is discovered, the bones are examined to see if further research is necessary.