TOPIC 7. GUNPOWDER AND OTHER EXPLOSIVES Flashcards
In the investigation of crimes involving the use of firearms, three most important problems may arise. The first and probably of primary importance is the problem of determining whether or not person has fired a gun with bare hands within a pertinent period of time
GUNPOWDER AND OTHER EXPLOSIVES
– because of its inherent defects modern ammunition plants abandoned the use of this.
Black Powder
– is the most widely used propellant. It can either be single base propellant or double propellant.
Smokeless Powder
– possibly the oldest known explosive. It is consists of an intimate mixture of charcoal – 15%, sulfur – 10% and potassium or sodium nitrate 75%. When exploded in open space the following reaction occurs: 2KNO3 + 3C + 3CO2 + K2S + N2
BLACK POWDER
– the most widely used propellant. It is consists of Cellulose Nitrate or Glyceryl Nitrate combined with Cellulose Nitrate and some stabilizers.
SMOKELESS POWDER
– different types of ammunition fired in the same weapon and from the same distance may give different pattern.
Type and Caliber of the Ammunition
– a weapon with 2 inches barrel will deposit residues over a larger area than a weapon having a five inches barrel even though they are fired at the same distance and with the same type of ammunition.
Length of the Barrel of the Gun
– affects the speed with which powder burns. Powder having lesser amount of moisture will burn more rapidly and completely within a given time yielding greater amount of residue.
Humidity
– in high winds the residue will be blown in the directions of the wind yielding a scattered pattern.
Wind Velocity and Direction
– firing vertically, slightly greater than firing horizontally from the same distance. Powder residues have weight. When gun is fired downward o vertically all of the residence will fall on the target, but when fired horizontally some of the residues are likely to fall short of the target.
Direction of Firing
– a test to determine whether a person fired a gun or not with bare hands.
Diphenylamine Paraffin Test or Dermal Nitrate Test or Lunge Diphenylamine Test
– the taking of the cast to extract the nitrates embedded or implanted in the skin.
Paraffin Test
– the chemical aspect of the test. It determines the presence and distribution of nitrates.
Diphenylamine Test
Due to its alkaline character,Ballistolis ideal for cleaning and maintaining black powder firearms. The residues from black powder in chambers and bores are acidic.
Ballistol neutralizes and dissolves them
BLACK POWDER SOLVENT
The leakage of powder is apt to occur when the gun fired is old weapon where the breech mechanism is no longer tightly titled and when the gun used is of the revolver type.
BLACK POWDER SOLVENT
– slight burning
Singeing
– blackening of area around the bullet hole
Smudging
– individual species of nitrates around the bullet hole visible to the naked eye. It is a black coarsely peppered pattern.
Tattooing
– This test is used if the powder particles are deeply embedded.
Walker’s Test
– A weapon on high velocity projectile: Gunshot range is difficult to estimate due to high velocity of the projectile and the wide variation produced on the wound of entrance. The tissue through which the bullet passed is usually bruised in varying degree. As a general rule the size of the wound closely appreciate the size of the bullet.
Rifle
– The projectile is a collection of small shot consisting of lead pellets that vary in size with types of cartridge.
Shotgun or Sporting Gun
– a black substance that is formed by combustion rises in fine particles and adheres to the side of the barrel conveying the smoke.
Soot
– formation of rust inside the barrel after the gun has been fired is good indication for the determination of the approximate time the gun has been fired.
*If a gun has not been fired at all, no rust can be detected inside the barrel of the gun.
*If a gun has been fired, Iron salts are formed and are found inside the barrel. This iron salts are soon oxidized resulting in the formation of rust.
Rust
– presence of nitrite (NO) is determined by the addition of diphenylamine reagent. If the color becomes blue, nitrites are present and we may say that the firearm could have been fired recently.
Nitrite
– presence of nitrates (NO) is determined by the addition of diphenylamine reagent. If the color becomes yellow green, nitrates are present and we may say that the forearm could have been fired but not recently.
Nitrate
The Crime Laboratory does not only examine explosive confiscated from some lawless elements of society that they utilize for criminal purposes, but also explosives used in illegal fishing.
EXPLOSIVES
– is any substance that may cause an explosion by its sudden decomposition or combustion. A material either a pure single substance or mixture of substances which is capable of producing an explosion by its own energy. When exploded always accompanied with the liberation of heat and almost with the formation of gas.
Explosive
Examples: Lead Azide Ph (N) Ammonium nitrate NH NO
Inorganic Compound
Examples: Trinitrotoluene (TNT); picric acid (trinitrophenol nitrocellulose; mercury fulminate Hg(ONC)
Organic Compound
Examples: Black Powder – used today mainly as igniter for nitrocellulose gun propellants and also in pyrotechnics.
Mixture of oxidizable materials and oxidizing agents that is no explosives separately
– are combustible materials containing within themselves all oxygen needed for their combustion which burn but do not explode and function by producing gas which produces explosion.
Examples: Pyrotechnics, Black Powder, Smokeless Powder, Firecrackers and Pyrotechniques
Propellants or Low Explosives
– explode or detonate when they are heated or subjected to shock. They do not burn. Sometimes they do not even contain the elements necessary for combustion. The materials themselves explode and the explosion results whether they are confined or not.
Examples: Mercury Fulminate and Lead Azide
Primary Explosives or Indicators
– explode under the influence of the shock of the explosion of a primary explosive. They do not function by burning, in fact not all of them can be ignited by a flame and in small amount generally burn tranquilly and can be extinguished easily. If heated to a high temperature by external heat of by their own combustion, they sometimes explode
High Explosives
– most readily available and cheapest salt of nitric acid. White compound used as a solid oxidizer in explosive mixture.
AmmoniumNitrate (AN)
– made by mixing nitroglycerine with powdered clay or sawdust.
Dynamite
– the most widely used explosive. Used mostly for military explosive. A safe explosive, it will burn but does not explode set on fire.
TNT – or Trinitrotoluene
– widely used in industrial explosive. Has been the main component in many dynamites. It is a mixture of Nitric Acid, Sulfuric Acid and Glycerine. Oily liquid that is very dangerous because the slightest shake will cause it to explode.
Nitroglycerine (NG)
– a military explosive that looks like ordinary putty or molding clay. Military explosives are chiefly solids or mixtures formulated as to be solid at normal temperature of use.
Plastic Explosive
– also called trinitrophenol.
Picric Acid
– also called trinitrophenol.
Picric Acid
– often referred to as a plastic explosive. White and dough like in consistency. It is commonly encountered of the RDX based explosive.
C – 4
– Also called hexagon or cyclonite, cyclotrimethylenetrinitramine. A plastic explosive. Most important military explosives used today.
RDX – (1,3,5 – trinitro –1,3,5 triazacyclophexane)
– the principal constituent in the filter used in tear gas solutions. Commonly used tear gas.
Chloroacetophenone (CN)
– is an incendiary device, not a bomb. Easily constructed of the most common materials. Consists of frangible container, like glass bottle filled with gasoline or any inflammable mixture and having a piece of absorbent cloth for a wick or fuse. To function the container is turned upside down and the wick absorbs the flammable mixture, the wick lighted and thrown. On impact the bottle breaks scattering the flammable mixture which is ignited by the burning wick.
Molotov Cocktail
– consists of 2/3 and 1/3 gas and sulfuric acid respectively. A blotter which has been saturated in potassium chlorate and sugar is wrapped and secured to the bottle. A snowball consists of potassium chlorate and sugar mixture embedded in a wax mold using a length of safety fuse for an ignitor.
Modern Molotov
Discovered in 1846 still remains the most powerful explosive in practical use
Nitroglycerin
Discovered in 1846 still remains the most powerful explosive in practical use
Nitroglycerin
Discovered in 1846 still remains the most powerful explosive in practical use
Nitroglycerin
Has been called the most dangerous explosive material in the world it also no. 3 in k.s lanes list the 10 most dangerous chemicals known to man
Azidozide azide
