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Glass _ Soil Review - Duluth High School

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					Glass & Soil
Review
•What is the state of
 matter of glass at room
 temperature?
•It is an amorphous solid.
The main compounds in
glass are __________.
Silicon Oxides & Metal
Oxides
•What is the name of the
 glass that is made by
 passing the molten glass
 through rollers?
•Ordinary or rolled glass
•Window glass is
 (more/less) dense than
 water.
More dense
The two most important
physical properties of
glass used for
identification are:
•Density and refractive
 index
True or False
• Density is not
  homogeneous over sheet of
  glass
•True
True or False, when glass
shatters it is easy to
reconstruct the original
shape.
•false
•This type of glass involves a
 treatment where the glass is
 heated to 620  oC and then

 cooled rapidly. What is the
 name of this glass?
•Tempered or Safety
 Glass
•Name the type of glass
 that is used for flat glass,
 container glass, and
 electric light bulbs.
•Soda Lime Silicate
•The fracture pattern of
 glass usually has
 __________ lines.
•Conchoidal
•This type of conchoidal
 line appears first when
 glass is fractured.
•Radial
For a ______________
fracture, the
perpendicular end, faces
the surface on which the
force originated.
•concentric
•In a forensic laboratory,
 a technique frequently
 used to determine the
 density of glass involves
 the use of ___________
•Density – Gradient tubes
•Stress marks on the edge of
 a radial crack near the
 point of impact are
 ___________ to the side on
 which the force was applied.
•parallel
True or False
A crater-shaped hole is
narrower on the side where
the projectile entered the
glass.
True
True or False –
It is easy to determine from the
size and shape of a hole in glass,
whether to was made by a bullet
or some other projectile.
False
A piece of window glass is submerged
in vegetable oil. The outline of the
glass is visible. When light is shown
behind the glass, a bright halo appears
near the border of the glass. This
bright halo is called a _________.
•Becke line
________ glass has a layer of plastic
between two pieces of ordinary window
glass.
Laminate or laminated
Name at least one out of
three common problems
associated with glass
analysis (glass comparisons)
•Find and measure properties
•Associate one glass
 fragment with another
•Minimize or eliminate other
 sources
•The bending of light as it
 travels through one medium
 into another is known as
 ________.
Refraction
As light goes from the air
into a liquid sample, the
bending of light is due to
a(n) ___________ in velocity
of the light.
•decrease
At25 oC   the refractive index
of water is 1.333. This means
that light travels 1.333x
__________ in a vacuum
than in water.
•Faster
______________ solids
 •Refract a beam of light in
  two different light-ray
  components (wavelengths)
 •Results in double
  refraction
•Crystalline
The numerical difference
between these the two
refractive indices of a
crystalline solid is known as
________________.
•Birefringence
This is an example of.. . . . . .
•Birefringence
• Technique used to determine
  the refractive index of a glass
  sample is known as the
  _____________ method.
•Immersion
• As the velocity of a fast moving
  projectile decreases, the
  irregularity of hole and cracks
  ____________.
increase
Exhibit (a) only shows a __________ fracture
Radial
Glass Collection

True or False
All broken glass at a crime
scene must be collected,
regardless of the size.
FALSE
Know ALL of these steps for Glass
collection
• Collect all glass found for piecing
• Submit all glass evidence found in
  the possession of the suspect
• Collect only a representative
  sample of broken glass remaining at
  the crime scene
True or False
Once collected glass should
be wrapped up in paper to
prevent further damage.
False,
Packaged in solid containers
to avoid further breakage
Soil Collection
Standard/reference soils should be taken
from the crime scene at various intervals
within a ______-yard radius of the crime
scene.

This will be used as a comparison to
questioned soil.
100
Soil is a mixture of _______ and
_________ material.
Soil is a mixture of organic and
inorganic material.
An example of 100% inorganic
soil is _________while an
example of a nearly 100%
organic soil would is ________.
• An example of 100% inorganic
  soil is sand while an example
  of a nearly 100% organic soil
  would is peat.
The inorganic part of soil is
________.
minerals
The organic part of soil is known as
_______ which is made up of
__________________.
Humas

decayed plant and animal material
The forensic definition of soil
includes many things,
including:
1. Bits of grass 9. Seeds
2. Cinders       10. Animal
   matter
3. Asphalt       11. Spores
4. paint
5. metals
6. concrete
7. Bricks
8. Vegetation
List the five major factors
that influence a soil’s
composition.
1. Climate
2. Parent material
3. Living organisms
4. Topography
5. Time
•True or False
Soil is class evidence - cannot
be individualized to a
particular location
•True
•True or False
•There is no classification
 system for soils
•True – only guidelines
True or False
Soils can be easily transported
True – which makes it excellent
trace evidence.
True or False
Soils within a few meters
horizontally or vertically
differ
True
True or False
After removing the first 2- 3
inches of top soil, a forensic
soil analyst can tell if a body
has been buried below.
True

				
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