CHE 107 Lecture Notes - Lecture 23: Soot, Griess Test
10 Oct 2018
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Document Summary
When a firearm is discharged, certain things besides the bullet are propelled out of the barrel toward the target: unburned particles of gunpowder, partially burned particles of gunpowder, smoke. If the muzzle of the weapon is sufficiently close, these products will be deposited onto the target. Presence of scattered specks of unburned & partially burned powder grains w/out accompanying soot is often observed at distances up to 25-36 inches. More than 3 feet = no deposit of powder residues: only visual indication is a bullet wipe, bullet wipe: dark ring around the hole, residue: When garments/other evidence relevant to shooting are received in crime lab, surfaces of all items are first examined microscopically for presence of gunpowder residue: greiss test: needed to detect gunpowder residues that aren"t visible. Firing distances involving shotguns must again be related to test firing: muzzle to target distances can be established by measuring spread of discharged shot.
