what things are visible which instruments are used, what are the major functions of the instrument used and which is the best technique used by the scientific officer to compare whether two soil samples are from same area or different area.

1. SOIL
Submitted By:
ANJALI AWASTHI
M.Sc Forensic Science
4th Sem

2. Introduction:
• Soil is a common form of physical evidence found at the scene of crime such
as hit-and- run Accidents, rapes and burglaries.
• Soil from the crime scene may be picked up by an automobile(tyres) thus can
be a probable link between automobile and the crime.
• It is a naturally occurring material which usually contains clay, rocks, coal,
plant material and other debris in addition to its mineral constituents.
• Soil is heterogenous in nature and varies widely from place to place due to the
effects of wind, water, living organisms, mining and agriculture.
• Thus, soil from different places will have different individual characteristics.

3. • Forensic examination of soil is not only concerned with analysis of naturally
occurring rocks, objects such as glass, paint chips, brick fragments.
• A number of physical and chemical methods have been used for identification of
source correspondence as well as for comparison of two soils.
• Soil science has two branches study- Edaphology and Pedology.
• Edaphology is totally concerned with influence of soil on living beings.
• Pedology is the formation, morphology and classification of soil in their natural
environment.

4. Method of Examination
• Microscopic Examination- In this we observe the colour of the soil as such and after
drying in incubator at 105̊C.
Observing the nature, size and shape.
Sorting out the foreign elements as paper pieces, leaves, seed, glass fragments, animal
and wood matters etc.
• Sample Preparation- Set of sieves (ranging in size from ASTM) in motor driven sieve
shaker.
Method- Arranging the set of sieves in numerical order with smallest number (largest
mesh size) at top and largest number (smallest mesh size) at the bottom
Place the sieve on the shaker and pour the soil sample on the top sieve.
Further, placing the cover on the upper sieve, fasten the binding straps. Switching on
the shaker and allow the shake to operate for at least 5 minutes.

5. Removing the sieve cover and separate the sieves. Collecting the soil retained in each sieve
separately and marked them.
• Removal of Blood from Blood-stained Soil-
Method- We prepare saline water of about 0.95% i.e. dissolve 50mg of NaCl in 100ml of
distilled water.
Pour the blood stained soil sample in saline water and stir for separation of blood.
After few hours, decant the water and wash with distilled water. Drying the sample in hot
oven or on hot plate at 105̊C and keep it in Desiccator.
Observation- with the help of Stereo- Microscope.
The soil that is dried in the incubator is analysed by checking the presence of insoluble
carbonate and the presence of soluble Iron present in the Questioned and Sample soil.
If there is appearance of bubble arising then for confirmation we add 2-3 drops of
freshly prepared solution of Potassium Ferrocyanide. On addition Bluish-green color
marks the presence of Soluble Iron in the soil.

6. Pattern of Soil when moist

7. When reacted with
Conc. HCl

8. When reacted with
K4Fe(CN)6

9. • Particle Size Distribution- Set of sieves (ranging in size from ASTM No.5
o 200), Motor driven sieve shaker, Analytical balance with an accuracy of
±0.0002gm, Standard Weight.
Method- We take an accurately weighed quantity of soil i.e. 50mg. Then we
arrange the set of sieves in numerical order and shake the soil in the same
manner as I mentioned earlier. Further we collect the amount of soil retained
in each sieve separately.
Percentage of soil retained on sieve No= (Weight of soil retained on
sieve)/(Total weight of soil taken)

10. Motor Driven Sieve
Shaker

11. Mesh size varies
according to size.
• Above figures determine the mesh size as well
as the amount of soil each mesh retains after
sieving process.
• Further according to grain size soil is
distributed at each and every step and further
measured.

12. Density Gradient
• This is a capillary of 6mm thickness used to
compare the density of soil we get from the
crime scene.
• We generally observe samples i.e. Questioned as
well as original sample of soil are from same
place or not .
• If both have same density then occupy same
range.

13. Loss on Ignition
• Instrument used to check loss on
Ignition of soil is seen by Muffle
Furnace.
• Ignition of soil takes place at about 700-
800̊C for 1hour.
• This process is done to check the
change in color and loss of soil taken
before and after Ignition.
• Inside of Muffle Furnace containing
soil samples.

14. Instrumental Analysis
• Neutron Activation Analysis
• X-ray Emission Spectrographic Analysis
• Analysis of Organic comparison
• Mineralogical Classification
• Diffraction Thermal Analysis
• Comparison of Micro-organism Content.

15. Forensic Significance