GUN POWDER

GUN POWDER

1. GUN POWDER

2. Overview Evolution of gun powder Function of gun powder Uses of gun powder Detection of gun powder Unburnt gun powder

3. Evolution of gun powder Gunpowder is the first explosive to have been developed "Four great inventions“ It was invented in china during late 9 th century The chinese first used gunpowder in warfare in 904, as  "flying fires.“ Gunpowder was invented by chinese alchemists in the 9th century.

4. The use of gunpowder in warfare during the course of the 19th century diminished due to the invention of smokeless powder. Black powder was first produced by Roger Bacon in 1250 Immortality By the 1700’s the invention had spread around the world. Gunpowder is often referred to today as "black powder" to distinguish it from the propellant used in firearms.

5. Propellant Propellants –material that is burnt to propel ammunition Black powder Smokeless powder Semi smokeless powder 1gm of black powder 280 cc of gas

6. What is gunpowder? An explosive material- black powder Potassium Nitrate(75%) Charcoal(15%) Sulfur (10%)

7. Functions Charcoal – Fuel Sulfur – Binding Fuel The temperature of ignition Speed of combustion Improves shelf life by- reducing water absorption Potassium nitrate-Oxidizer Modern Smokeless powder Lead, barium ,antimony ,copper ,iron ,carbon monoxide , Nitrates,nitrites,zinc,nickel ,carbon particles

8. Composition Smokeless powder Single base powder –Nitrocellulose Double base powder Nitrocellulose+ Nitroglycerin Triple base powder Nitrocellulose+ Nitroglycerin+ Nitroguanidine 1gm of Nitrocellulose - 950 cc of gas Less smoke Blackening Completely burnt Not used in muzzleloading

9. Uses for gunpowder

10. Other features Gunpowder takes less than half a second to ignite. Gunpowder is still being used today. Gunpowder can reach heats of up to 800 degrees Celsius.

11. Gun powder residues Fire arm discharge residues or cartridge discharge residues A mixture of material that originate from firing a gun and its residues that is deposited on the hands and clothes of someone who discharges a firearm .

12. Distribution of GSR Skin of hand-thumb & index finger Lateral 1/3 rd of palm Anatomical snuff box region

13. Collection techniques By adhesives –Tape lifts, glue lifts ,stainless steel studs Swabs – Isopropanol as solvent Vacuum lifts – clothings Nasal collection – 48 hrs Hair –fine toothed comb Dead Protect from action of friction Paper bag Maintenance of the chain of custody

14. Detection of gun powder Colour test Anodic stripping voltammetry Neutron activation analysis Flameless Atomic absorption spectroscopy Scanning electron microscopy

15. Detection gun powder residue Dermal nitrate test / paraffin test Nitrates and nitrites Diphenylamine/sulfuric acid reagent

16. Harrison – Gilroy test : Detects metal containing components Sample collected by cotton swab soaked in 0.1 M HCl . Triphenylmethylarsonium iodide Antimony, barium and lead

17. Griess test Samples – dissolve in ether Add marshall reagent 0.2 % Naphthylenediamine dihydrochloride 2% sulphanilamide in 5% phosphoric acid Cloth Hand Hair Face

18. Anodic strippling volumetery First step –cleaning step Second step-electroplating step Third step- equilibrium step Fourth step-stripping step Hcl –sensitive method

19. Neutron Activation Analysis Subjected to gamma ray spectrometry . Detects antimony, barium and copper . Advantages –highly sensitive & accurate Multi element analysis Disadvantages – Nuclear reactor is required Trained staff,costly

20. Atomic Absorption Spectroscopy And Flameless Atomic Absorption Spectroscopy Electron of atoms can absorb energy and be promoted to a wavelength Elements in the samples can be identified by missing wavelength Atomic absorption spectroscopy Detects antimony, barium and copper

21. Advantages & disadvantages Easy sample preparation Easy to use Low detection limits Low investment & cost Well documented technique Detects one element at a time Lack of specificity Elements are not unique contains some environmental Contaminants

22. SEM-EDX Detection of these particles is an indicator that the suspect fired the gun .

23. Un-burnt powder Incomplete combustion of gun powder Responsible for tattooing Penetrate dermis Appearance – multiple punctate abrasions Detection –hand lens /dissecting microscope IR Photography

24. Reference Principles of Forensic Medicine & Toxicology Rajesh Bardalae Knights Forensic Pathology Dr.B.R SHARMA Forensic science in other criminal investigation -5 th edition Anil Aggrawal textbook of forensic medicine and toxicology . Narayan reddy essential of forensic medicine