In view of these well-known facts, it would always be well to insist in cases of this kind that the saw alone should be used and not the hammer nor the chisel. When a cranial bone is fractured blood is poured out from the ruptured vessels, as is always the case with any bone. Its amount varies indefinitely with the number and size of the ruptured vessels, the activity of circulation, the length of time a person lives, etc. The blood may collect in circumscribed masses or become infiltrated in the surrounding tissues, although usually both phenomena are observed. The extent to which infiltration takes place depends upon the quantity of blood and the nature of the surrounding tissues. In loose tissues like those about the orbit infiltration is much more rapid and extensive.
Examination of the Weapon.—French medical jurists have tried to indicate how we may determine the time elapsed between the death of a person and the discharge of a weapon found near the body, but exact statements in this matter are utterly out of the question. Certain facts bearing on the subject are these: When recently discharged there will be found adhering to the barrel of the piece and consisting of the fouling of which sportsmen complain, a quantity of potassium sulfid mixed with charcoal. This is shown by its forming a strong alkaline solution with water, evolving an odor of hydrogen sulfid, and a dark precipitate with a solution of acetate of lead. Depending upon the degree of exposure to air and moisture, after some hours or days this sulfid becomes converted into potassium sulfate, which forms a neutral solution with water and gives a white precipitate with acetate of lead; but if a considerable time has elapsed since the discharge of the piece oxid of iron (iron rust) with traces of sulfate may be found (Ann. d’Hygiene, 1834, p. 458; 1837, p. 197; 1842, p. 368).
Was the Weapon Fired from a Distance or Near By?—A gunshot injury from a bullet implies at least one wound, namely, that of entrance, and perhaps another, that of exit. It does not always happen that the bullet passes through the body. The appearance of the wound of entrance is usually one of irregular circular puncture, its edges perhaps slightly torn or lacerated, with a purplish or dark areola, varying in width from a line or two to one-half inch. When the weapon is fired close to the body there are likely to be more or less powder-marks, and possibly actual burning from the heat and flame of the gunpowder. If the part of the body injured had been covered by clothing at the time, the marks of powder and of burning would probably be confined to the same. Bleeding is usually slight and occurs more commonly from the wound of entrance than from that of exit. Regularity of either of these wounds depends in large measure upon the angle at which the bullet has struck the surface. When striking very obliquely the wound may be more oval or the bullet may have ploughed a furrow or a channel, by a study of which the relative position of the assailant and the assailed at the moment of injury may, perhaps, be determined. It is of importance to determine if possible the approximate distance at which the bullet was fired, since the question of self-defence, for instance, may hinge upon evidence of this character. The charge of powder and the weight of the bullet being known, one may sometimes estimate this distance by the depth of penetration or the appearance of the bullet. Still, the nature of the tissues must figure largely in such consideration. Many suicides who shoot themselves in the head show only one wound of entrance and none of exit.
Experiments Testing Powder-Marks.—Powder-marks and burns from weapons ordinarily used will scarcely appear when the distance has exceeded ten or twelve feet. LaChese, of Antwerp, found that in firing a gun even from a distance of only four feet the skin was only partially blackened.
As the result of experiments made with a Ballard rifle, old style, .44 calibre, with bullets of 220 grains and 28 grains of powder, Dr. Balch, of Albany, found that powder-marks were made at distances as follows:
At two feet, particles too numerous to count, with some of the lubricant blown upon the board;
At four feet the same;
At six feet the same;
At eight feet, nine grains of powder;
At ten feet, five grains of powder in one case and six in another.