During the first few weeks after Rontgen's discovery reports were received from all over the world recording the great value of the new rays. The extraction of a bullet from a patient's leg had been facilitated by their use even though it had moved some five inches from the entrance wound. In Paris the rays had been used to diagnose a diseased thigh bone and in Berlin to watch the growth of new bone following a fracture. The technique devel oped rapidly and by the end of Feb. 1896 the method was in comparatively general use. Twenty minutes was the average time of exposure required to obtain a radiograph of an arm in 1896. In 1928 the exposure necessary for this purpose is a small fraction of a second and the result is of course infinitely better. In May 1896 the first exclusive X-ray periodical appeared in England. It was called the Archives of Skiagraphy, and the first number recorded an X-ray cinematograph film 4o f t. long show ing the movement of a frog's leg.
By 1897 systematic work was in progress on the biological effects of X-rays. This work had been stimulated by the early appearance of X-ray dermatitis or skin disease which had attacked various experimenters during the year 1896. It was very soon found that the action of the rays on physiological tissue was by no means consistent, some cells being stimulated by irradiation to rapid growth, others being killed and disintegrated. It was also observed that some cells exhibited much greater sensitive ness to the rays than others. These early experiments engendered the hope that X-rays would prove to be a powerful agent in the destruction of harmful bacteria in the human body—a hope that has, unfortunately, not been realized.
In 1897 Dr. Morton, of New York, obtained a remarkable radiograph of an entire and fully clothed adult body. The entire skeleton was shown and the total exposure was only 3o minutes. Noticeable among the very early medical applications of X-rays were their trial in the treatment of cancer and tuberculosis.
Although non-medical applications of X-rays are very largely a modern development, yet early in the history of the subject many such applications were suggested and even tried. One inter esting application was suggested in the year 1899; it was called the "Izambard" process of printing by X-rays. A number of sheets of sensitized paper were to be piled up and the copy, which was to be prepared with an ink which was semi-opaque to X-rays, placed on the top, the whole mass was then to be radiographed. Experiments with the method showed that a block of paper some two inches in thickness could be successfully radiographed with out undue distortion. There are obvious disadvantages about the suggestion which caused it to be abandoned.
The radiography of metals was recognized as an important future use of X-rays as early as Feb. 1896, when Prof. A. W.
Wright, of Yale university, radiographed a metallic weld and revealed a fracture which was not apparent to the eye. The very limited power of an X-ray tube prevented the development of this work for many years, but, as we shall see, it was to become hardly less important than the medical and surgical aspects. The examination of coal for impurities and ash was another early application which was to be revived some 3o years later in a more practical manner. ( Kemp, Colliery Guardian, pp. 539-541, Feb. 29, 1924.) A short list of the various applications of X-rays which were actually tried during the time immediately following the discovery is of prophetic interest in view of our later and more systematized knowledge of the subject. They had been used to detect the adulteration of flour and sugar with sand and chalk, and in connection with the general subject of food adultera tion the relative X-ray transparency of various foodstuffs was measured by Herr. W. Arnold in Germany. Other applications were :— To detect pearls in pearl oysters; To distinguish between real and artificial gems; To discover the contents of postal parcels; To recognize explosives and contraband in baggage ; To examine the insulation in electric cables.
The extraordinary value of Rontgen's discovery has been no where more in evidence than in medicine. Although the biological effects of the rays are so little understood, it seems to be quite clear that physiological cells react to X-rays in different ways and certain organs in the body respond much more readily than others. X-rays are a most efficient cure for ringworm, yet the treatment must be exercised with great caution because of the sensitiveness of the hair follicles to the rays, the action of which may produce baldness. During the World War 1914-1918 this depilatory property was taken advantage of in a singularly in genious manner. Tissue which was normally hair-bearing was first treated by X-rays, and it was then possible to use it for grafting in plastic surgery. Generally speaking, it has been found that X-rays in small doses tend to stimulate biological activity, while large doses tend to destroy such cells. It has been said that X-rays have a specially selective action on cancer cells and certainly their value in the treatment of cancer has been amply demonstrated. Some interesting investigations concerning the effect of X-rays on biological tissue have been published by Dr. W. Moppett, of Sydney, Australia (Moppett, Australian Medical Journal, vol. i. 15, April I I, 1925), who shows that the differ ence in the biological action of X-rays of slightly different wave length is considerable.