In dislocation of the jaw it may be necessary for someone to try to replace it before the doctor arrives. The mouth is open and the jaw fixed. The patient may even tell you he has felt the jaw slip out of its socket. Wrap your thumbs in cloth to prevent biting when the jaw snaps back in place. Place the thumbs on the tops of the lower teeth on each side, with the fingers outside, and push firmly down until the head of the bone can slip over the edge of the socket into place. As you feel the bone slipping into place, slide your thumbs out to the inner side of the cheek to prevent biting when the jaws snap together with the reducing of the dislocation. (b) _Fractures_--_Broken bones_--There are two classes of fractures: 1. _Simple_--In a simple fracture the bone is broken, but the skin is not broken; that is, there is no outward wound. 2. _Compound_--In a _compound_ fracture not only is the bone broken, but the jagged ends pierce through the skin and form an open wound. This makes it more dangerous as the possibility of infection by germs at the time of the accident, or afterward, is added to the difficulty of the fracture. _Symptoms_--As in dislocation, you should be familiar with the main symptoms of a broken bone. 1. When you look at the injured part it may or may not look like its mate on the other side. In the more severe fractures it usually does not. 2. When you try to move it you find more motion than there should be, if the bone has broken clear through; that is, there will seem to be a joint where no joint should be. 3. The least movement causes great pain. 4. The swelling is usually rapid. 5. The discoloration (black and blue) appears later; not at once, unless there is also a superficial bruise. 6. The patient is unable to move the injured part. 7. You may hear the grate of the ends of the bone when the part is moved, but you should not move the injured bone enough to hear this, especially if the limb is nearly straight; the detection of this sound should be left for the doctor. _Treatment_--Send for a doctor at once, and if it will be possible for him to arrive soon, make the patient as comfortable as possible and wait for him. However, if it will be some time before the doctor can arrive you should try to give such aid as will do no harm and will help the sufferer. You must handle the part injured and the patient with the utmost gentleness to avoid making a simple fracture into a compound one, or doing other injury, and also to give him as little additional suffering as possible. You will need to get the clothing off the part to be sure of what you are doing. Rip the clothing in a seam if possible when the fracture is in an arm or leg, but if this cannot be done, you will have to cut the material. Do not try to move the broken bone trying to get off a sleeve or other part of the clothing.