Glass can provide very effective evidence concerning a possible suspect. However glass has it's drawbacks and dangers to work with.

The forensic scientist uses the physical properties of glass to associate one type of glass fragment with another. One of these physical properties is density. Because different types of glass contain different combinations of metal oxides, they have different densities. Density refers to a material's mass per unit volume, and can be summarized in the formula: D = mass/volume

First the investigator must be careful working with glass as because it does shatter and can easily cut and injur. In the investigation lab it is important to work with tweesers to handle the glass, and always use a paper or plastic cup to weigh the glass.

The following is a good guidline for determining the density of glass samples.

The density of a substance remains constant, no matter what the size of the substance.so you can use many pieces together to make up a measurable amount of glass. 12 small piece of glass would be difficult to measure because it would be hard to deterrmine the volume of a single piece of glass. Therefore it is advisable to use enough pieces to weigh approximatly 8-10 grams.
3 steps you must take to find the density of the glass sample.

1. Weigh the sample to find its mass.
2. Determine the volume of the sample.
3. Divide the mass of the sample by its volume.

Materials:

• An "unknown" glass sample (divide into 2 samples approx 8 g each)
• Graduated cylinder (25 ml is best or largest 50 ml)
• Triple-beam balance
• Plastic cup (weighed to .01g)
• Tweezers
• Water
• Paper Towels
• Calculator

Procedure:

1. Place the first "unknown" glass sample in a plastic cup on a scale and determine its mass in grams (measured to .01). Record this mass on a Data Table that you create to organize your data.
2. Remove this sample from the scale. Repeat step 1 with an other sample of glass.
3. Place 30 milliliters of water in the graduated cylinder. Then add the "unknown" glass sample to the water in the graduated cylinder. Read the new volume on the cylinder in milliliters. Take the new volume and subtract 30 to find the volume of the piece of glass. Record this information in your data table.
4. Repeat step 3 for the other glass sample.
5. Divide the mass of each sample by its volume to determine the sample's density. Record the densities for the glass pieces in your data table.