Walker Test
Definition
Filter-paper transfer test for nitrites in propellant residue. The cloth is pressed against desensitised filter paper, sprayed with sulphanilic acid and alpha-naphthylamine, and orange-to-pink spots map the propellant pattern.
Related terms
- Bullet Wipe
- Greyish to brownish ring of lubricant, lead and copper rubbed off the bullet onto the margin of an entry hole in clothing....
- Contact Shot
- Muzzle pressed against skin or clothing at the moment of firing. Hallmarks are a stellate (star-shaped) wound from sub-dermal gas tracking, a...
- Modified Griess Test
- A contact-transfer colour chemistry test for nitrite-containing propellant combustion residue. Sulphanilic acid undergoes diazotisation with nitrous acid (from NO2 on the target...
- Powder Tattooing
- Stippling pattern of unburned and partially burned propellant grains embedded in the skin around an entry wound. Cannot be wiped off. Pathognomonic...
- Range of Firing
- The distance from the muzzle of the firearm to the target at the moment of discharge. Estimated from wound geometry, soot pattern,...
- Sodium Rhodizonate Test
- Colour test for lead. The cloth is treated with sodium rhodizonate followed by buffer; lead deposits give a pink-to-red colour, confirmed with...
- Soot (Blackening)
- Submicrometre carbon-rich particles from incomplete propellant combustion, deposited on the garment or skin surface around the entry hole at contact and near-contact...
Explained in
- Determination of Range of Firing in Firearm CasesFilter-paper transfer test for nitrites in propellant residue. The cloth is pressed against desensitised filter paper, sprayed with sulphanilic acid and alpha-...