A handy-book of forensic medicine and toxicology / by W. Bathurst Woodman and Charles Meymott Tidy.

Date:
1877
Catalogue details

Licence: Public Domain Mark

Credit: A handy-book of forensic medicine and toxicology / by W. Bathurst Woodman and Charles Meymott Tidy. Source: Wellcome Collection.

Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.

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    chemical phraseology, but gives us no directions how practically to examine fire-arms. Nor is Dr. Taylor’s account, given at page 515, so complete as might be wished. He does indeed say that the sulphide of potassium forms an alkaline solution with water, evolving a smell of hydrogen sulphide [like rotten eggs], and blackening the acetate of lead. He also states correctly enough that the white sulphate of potash forms a neutral solution with water, and gives a white precipitate of sulphate of lead with plumbic acetate. He also refers to the “ Ann. d’Hygiene,” [1834, i. p. 458, ibid., 1839, i. p. 197, and 1842, i. p. 368], and quotes the case of M. Dujarrier, whose death was carefully investi- gated in France. The question arose on this trial, whether by the mere discharge of powder, such a deposit of powder or charcoal took place at the mouth of the pistol as to soil the finger when introduced three hours after the alleged discharge. M. Boutigny’s experiments were adverse to this view—and he considered that the sulphate aud carbonate of potash were formed so rapidly that all the charcoal was consumed. But the facts proved on the trial overruled his experiments—and it seems clear that the quantity of powder used has much to do with the question. So also have its perfect or imperfect combustion, and the quality of the powder itself—the amount of charcoal in it—and perhaps the fineness or coarseness of the grain. [In firing large guns, such as the Woolwich In- fant, little cakes, or cubes of powder are employed. A small fine grain- powder would never do. “Ann. d’Hygiene,” 1848, i. 392.] Sonnenschein in his “ Handbuch der gerichtlichen Chemie,” goes more minutely into this matter of examining fire-arms. He admits that a determination of how lately a given fire-arm has been discharged, is often impossible. Yet we can often make a close approximation to the truth. Unless you have leisure to examine the gun or pistol at once, you should cover the end of the barrel, and wrap up the weapon in cotton wool. In examining it, begin with the outside first. If one of the old-fashioned flint and steel weapons [and a few such survive], you should examine the priming-pan first with a lens. If the weapon is loaded, the charge should be cautiously withdrawn. If there be a percussion-cap, remove this at once—and the same applies to cartridges. Save the cap, the cartridge, the powder, and the shot or bullets. Weigh the latter, and make drawings and measurements of the bullet. Count small shots as well as weigh them. Wrap up each article separately, and label carefully. Seal them up, and keep under lock and key. Examine the bore of the weapon, and other dimensions. AYeigh it also. Measure its diameters. The bullet or shots may require analysis in some cases.* Examine the ramrod if there be one ; also the lock, construction of the weapon, the pull of the trigger, &c. Look very carefully at any paper or other materials used as wads; also at the greasy matter used to lubricate. Newspapers may be used for wadding. Now wash the barrel thoroughly with distilled water, and filter the washings. Test the filtrate for sul- phuric acid (by barium chloride), for alkaline sulphides (by lead solution), * Lead is generally mixed with about J-, of arsenic to make small shot. For bullets it is preferred pare. A cast bullet has a small hollow in its centre. As mentioned, one of Sonnenschein’s cases had a large quantity of antimony in the metal of which the bullets were made. Tin, bismuth, anti other metals, are some- times added. And sometimes people melt pewter, and solder, and similar mixed metals to make bullets of them. Those used in the army are now punched out or pressed, and not cast.