146. A musket-ball will often lodge in the less dense parts of bones, such as the great trochanter or the condyles of the femur, without fracturing the bone; it will sometimes even pass through the femur above and between the condyles, merely splitting, but without separating the bone in parts or pieces. Balls sometimes lodge in the shaft of the femur without breaking it, and frequently do so in the tibia, the humerus, the bones of the cranium, and even in others of less size. Balls thus lodged will sometimes remain for years--nay, during a long life--without causing much inconvenience. It is, however, generally the reverse, and they are often the cause of so much irritation and distress that the sufferers are willing to have them, and even their limbs, removed at last at any risk. Whenever, then, a ball can be felt sticking in a bone, although it cannot be brought into view, it should, if possible, be dislodged and removed by the trephine, by small chisels, by small, strong-pointed curved elevators, or by any of the screws invented for the purpose, which have sometimes been found efficient. An apparently useful instrument of this kind is attached to the forceps for extracting balls; it is more frequently used in France than in England. When the ball can be seen as well as felt, the surgeon must be guided by his own experience and judgment with respect to the most fitting instruments. It is to be removed if possible, whatever may be the means used for its abduction, after the wound has been properly enlarged for the purpose. 147. When a ball merely grazes a bone without breaking it, and passes through the limb, and no splinters can be felt by the finger, dilatation is unnecessary in the first instance; although some small splinters may be cast off subsequently, or a layer of bone may exfoliate, requiring assistance for their removal. The bone may be fractured in a case of this kind transversely, and will require only the simplest treatment in an almost similar manner. 148. If the ball should enter and be flattened against the bone without breaking it, and lodge against it or in the soft parts, it should be sought for and removed. When the ball is flattened and the bone broken, it may lie between the broken extremities, and even lodge in one of them, rendering the case more complicated, and the necessity for close investigation more urgent. A leaden ball when striking on the sharp edge of a long bone, such as the spine of the tibia, has been known to be divided on it, without the bone being broken. This has happened in the arm. 149. When a ball strikes the shaft of a bone, such as the femur, directly and with force, it shatters it often in large, long, and pointed pieces, retaining their attachment to the muscles inserted into them. A fracture of this nature in the middle of the thigh will often extend downward into the condyles, and as high as, although rarely into, the trochanters. These are cases for immediate amputation.