Arson Detection - The Recovery of Flammable Liquids
Intro to Forensic Chemistry
Professor Ira S. Krull
October 14, 2012
CHEM 1107 10002
Arson is a serious crime that ran rampant during the 70’s and was the major cause of property damage in 1795, more so than any of the other common property damaging crimes including (burglary, motor vehicle theft, larceny, etc.). Subsequently, arson investigation is an essential component of any crime scene detection unit.
The investigation of a fire commences after it is extinguished and the area is deemed safe by fire fighters for examination. Similar to regular crime scenes, scenes of arson are to be preserved and their evidence is to be collected and preserved as quickly as possible, then analyzed. Unlike normal crime scenes, however, there are myriad complications that can occur under an arson investigation. For example, evidence can quickly and easily deteriorate and should always be placed in open paper bags, which allow the air to circulate.
In order for a fire to start it must have a fuel source (usually O2), an oxidant, and an adequate amount of energy in the form of heat. These three constituents, together in combination, result in the exothermic reaction of combustion, which produces heat and light. Now a new factor is being introduced (a self-sustaining chemical chain reaction). In the absence or removal of the components stated above, the fire will either not start or be extinguished through the processes of smothering (removal of oxygen), cooling (removal of heat), or starving (removal of fuel). Solids and liquids are incapable of combustion; rather they give off vapors that are able to burn (the process of pyrolysis). Reliant upon the materials associated with their, individual, combustion, the colors of flames are contingent upon the wavelength of light discharged. Carbon yields red, yellow, and orange flames, while...