1. 4-3 Forensic Analysis of glass
Unit 4: Properties of Matter and the Analysis of Glass

2. Comparing Glass Fragments
To compare glass fragments, a forensic scientist evaluates two important physical properties:
refractive index
Density

3. refractive index
The immersion method is used to determine a glass fragment’s refractive index.

4. immersion method
It involved immersing a glass particle in a liquid medium whose refractive index is adjusted be varying its temperature.

6. refractive index
At the refractive index match point the contrast between the glass and liquid is at a minimum.

7. Density
The floatation method is used to determine a glass fragment’s density.

8. Flotation Method
It involves immersing a glass particle in a liquid whose density is carefully adjusted be adding small amounts of an appropriate liquid until the glass chip remains suspended in a liquid medium.

9. Glass fracture patterns
By analyzing the radial and concentric fracture patterns in glass, the forensic scientist can determine the direction of impact by applying the 3R rule.

10. Radial fracture patterns

11. 3-R Rule Radial cracks for a Right angle on the
Reverse side of the force.