moved from its wooden case during the process, and it is not necessary to conduct the proceeding in a dark room. The tube should be from twelve to fifteen inches away from the surface of the body. The plate must be fastened to the surface exactly opposite the tube. It is necessary to observe care in the adjustment of the plate, because the Xrays travel only in straight lines, and any carelessness of adjustment will lead to curious and misleading aberration in the picture. The length of exposure necessary varies with the thickness of the tissues, the structure of the part, the nature of the body we wish a picture of, and the perfection of the apparatus, from three minutes to one hour. Prolonged exposure is undesirable if it can be avoided, as it may produce an X-ray "burn."

The so-called X-ray "burn" is not a burn at all. A burn is due to the contact of heat, is accompanied with pain from the moment of application, and is followed by inflammatory changes, beginning on the surface. An X-ray "burn' is not manifest for several days or even several weeks after the application of the rays, at which period an inflammatory or a gangrenous process arises, which begins within the tissues and subsequently involves the surface. These burns are often accompanied by loss of hair or nails in the damaged area, they require months to heal, if they heal at all, are very painful, and are not improved by treatment which relieves ordinary burns. In some cases the consequences are very serious. In a case reported by J. P. Tuttle, it became necessary to amputate the thigh. The lesions occasionally produced by the X-rays are probably trophic changes. Sections made by Vissman from Tuttle's case indicated that the lesion was a gangrenous process due to arteritis of the smaller vessels. These X-ray injuries are most liable to occur when a Ruhmkorff coil is used, and no such condition has been caused by a static machine (Tuttle). It has been suggested that a thin piece of aluminum placed upon the part while it is exposed to the X-rays will prevent the occurrence of these injuries. Skin-grafting may succeed in remedying an ulceration, but, as a rule, the grafts do not grow, or if they adhere, are very apt to break down after a time. In many cases the best treatment is excision (Powell).

The uses of the X-rays are legion. They are of the greatest possible value in the location of foreign bodies, especially bodies of metal, glass, or bone, such as bullets,

1 E. B. Bronson, in the debate on J. P. Tuttle's case, Medical Record, March 5, 1898. Med. Record, May 5, 1898

1. Gunshot-wound of the Lung. Rib-resection for secondary hemorrhage into the pleural sac ten days after the injury; bullet not removed. Hemorrhage arrested by packing with gauze. Skiagraph taken three months afterward shows the bullet. (Author's case.) 2. Fracture of Lower End of the Femur. Reduction of fragments impossible because of the interposition of a loose piece of bone and much muscle between fragments. (Author's case.)

3. Case shown in Figure 2, Three Months after the Operation of Wiring. Nine months after operation, the man is walking about with ease, and the wire is still in place.

(The above skiagraphs are from the X-Ray Laboratory of the Jefferson Medical College Hospital.)

and needles, glass, splinters, etc. Bullets are readily detected in the extremities; have been found in the lungsubstance and bronchi (Rowland), in the brain (Schier, Brissaud and Londe, Henchen and Sennauer, Bruce, Willy Meyer), in the abdomen, the pelvis, a joint, the spine, and the eye. The X-rays will enable us after an abdominal operation to locate a Murphy button and tell when it has loosened and descended. Foreign bodies, especially if

X RAY PLATE

FIG. 333.-W. M. Sweet's X-ray apparatus for locating foreign bodies.

metallic, in the esophagus, stomach, intestine, and air-passages; enteroliths, and mineral calculi in the salivary ducts, bladder, ureter, and kidney, can be detected. Henry Morris tells us that a calculus in the kidney may exist and yet escape detection with the rays, because the kidney is very deeply placed, is under the ribs and close to the vertebral column. Occasionally a drainage-tube lost in the pleural sac may be discovered. Gall-stones cannot be discerned. The rays may fail to disclose a foreign body because of its being overshadowed by a bone (Carless), but prolonged expos

ure or the taking of another picture with the part in another position will bring it into view. In many cases a skiagraph does not indicate how deeply in the tissues a foreign body lies, or upon which side of a bone it is lodged.' If there is doubt, take several pictures from different positions (triangulation), skiagraph over a surface marked in squares, insert guide-needles into the tissues before taking the final picture, or employ Sweet's apparatus. Sweet's apparatus has been used successfully for the location of foreign bodies in the eye, but a modification of the original apparatus has recently been used to skiagraph other regions of the body. Fig. 333 shows this apparatus. The negative exhibits the pointers, and the position of the foreign body can be determined by the use of projection-lines (Figs. 334, 335). In detecting fractures and dislocations the Röntgen rays are of great value, especially when there is much swelling, when there is little displacement, and when the fracture is in or about a joint. The rays enable us to determine the nature of the injury, the amount of splintering, the exist

FIG. 334.-Outlines of negative taken by Sweet's method.

ence of impaction, the question whether or not the fragments are in contact or can be brought into contact; the direction of the line of fracture, the variety of deformity, the existence of more than one fracture, the presence of epiphyseal separation or dislocation alone or with a fracture,

1 Battle's case in Lancet, Feb. 29, 1896.